Can you eat a dusky shark?
Dusky shark
The dusky shark is a generalist that takes a wide variety of prey from all levels of the water column, though it favors hunting near the bottom. A large individual can consume over a tenth of its body weight at a single sitting. The bite force exerted by a long dusky shark has been measured at over the area at the tip of a tooth. This is the highest figure thus far measured from any shark, though it also reflects the concentration of force at the tooth tip. Dense aggregations of young sharks, forming in response to feeding opportunities, have been documented in the Indian Ocean.
Sailfin roughshark
"Oxynotus paradoxus" is a rare shark found in the deep waters of the ocean from about 265–750 m below ocean level. At birth, "O. paradoxus" is about 25 cm in length and can grow up to 118 cm in length. It has a compressed body form with a blunt snout and a wide, flattened head. "O. paradoxus" has two tall, narrow and pointed dorsal fins that contain concave trailing edges, but no anal fin. The first dorsal spine trails back, a unique feature of this species of "Oxynotus". Both spiracles are relatively small compared to other sharks and are almost completely circular. The top teeth of "O. paradoxus" are lanceolate, but the lower teeth are blade-like. Each set of both upper and lower teeth contain 12 rows of teeth. The flank dermal denticles contain a central cusp next to two lateral cusps and a second middle cusp above the primary cusp.
Shark meat
Shark meat is popular in Australia, where it is known as flake. Flake is sourced primarily from gummy shark, a small, bottom-feeding species abundant along the east coast of Australia. Flake can be purchased as a ready-made meal from most Australian fish and chip shops, usually in the form of battered or grilled fillets.
Whitespotted bamboo shark
Juvenile sharks need a higher intake of carbon than adults sharks, especially during the wet seasons. White spotted bamboo sharks have an advantage in finding carbon sources because they are benthic predators (meaning they prey on fish near the sea-bottom), as opposed to pelagic sharks like the spadenose shark. That, combined with the fact that these species of sharks have, like most sharks, electroreceptors (ampulae of lorenzini) along their snout to help them locate prey that is buried in the sand and mud, makes them very efficient users of detrital carbon resources.
Smalleye pygmy shark
The smalleye pygmy shark ("Squaliolus aliae") is a little-known species of squaliform shark in the family Dalatiidae, found in water deep near Japan, the Philippines, and Australia. It migrates vertically daily, spending the day in deep water and the night in shallower water. One of the smallest shark species, the smalleye pygmy shark is known to reach only long. It has a blackish, spindle-shaped body with relatively small eyes, and a spine preceding the first dorsal fin, but not the second. Bioluminescent photophores occur on its underside, which may serve to disguise its silhouette from predators. This species feeds on small squid, krill, shrimp, and bony fishes. It is aplacental viviparous. The International Union for Conservation of Nature has assessed it as Least Concern, citing its wide distribution and lack of threat from fisheries.
Whale shark
The whale shark is found in open waters of the tropical oceans and is rarely found in the water below . Modeling suggests a lifespan of about 70 years, but measurements have proven difficult. Whale sharks have very large mouths and are filter feeders, which is a feeding mode that occurs in only two other sharks, the megamouth shark and the basking shark. They feed almost exclusively on plankton and small fishes, and pose no threat to humans.
Horn shark
Some 95% of the adult horn shark's diet consists of hard-shelled mollusks (e.g. bivalves and gastropods), echinoderms (e.g. sea urchins) and crustaceans (e.g. crabs, shrimp, and isopods). To crack their shells, the horn shark generates the highest known bite force relative to its size of any shark, well in excess of other measured species such as the spiny dogfish ("Squalus acanthias") and the blacktip shark ("Carcharhinus limbatus"). One study found the average bite force for this species in the wild to be 95 N with a maximum of 135 N, while under experimental conditions sharks could be induced to bite with over 200 N of force. Large horn sharks that feed mainly on sea urchins (particularly the short-spined purple urchin, "Strongylocentrotus purpuratus") have their teeth and fin spines stained purple.
Cookiecutter shark
Virtually every type of medium- to large-sized oceanic animal sharing the habitat of the cookiecutter shark is open to attack; bite scars have been found on cetaceans (including porpoises, dolphins, beaked whales, sperm whales and baleen whales), pinnipeds (including fur seals, leopard seals and elephant seals), dugongs, sharks (including blue sharks, goblin sharks, basking sharks, great white sharks, megamouth sharks and smalltooth sand tiger sharks), stingrays (including deepwater stingrays, pelagic stingrays and sixgill stingrays), and bony fishes (including billfishes, tunas, dolphinfishes, jacks, escolars, opahs, and pomfrets). The cookiecutter shark also regularly hunts and eats entire squid with a mantle length of , comparable in size to the shark itself, as well as bristlemouths, copepods, and other prey of more modest dimensions.
Parasitic attacks by the cookiecutter shark leave a round "crater wound", averaging across and deep. The prevalence of these attacks can be high; off Hawaii, nearly every adult spinner dolphin bears scars from this species. Diseased or otherwise weakened animals appear to be more susceptible; in the western Atlantic, there are records of emaciated beached melon-headed whales with dozens to hundreds of recent and healing cookiecutter shark wounds, while such wounds are rare on nonemaciated beached whales. The impact of parasitism on prey species, in terms of resources diverted from growth or reproduction, is uncertain.
Dumb gulper shark
The dumb gulper shark may grow to be long and has a long, robust head, a long, flattened snout, a large mouth, and large, green eyes, which help it see at 820 to 1260 ft (250 to 385 m) under water. The body is slender and of moderate size, and is grey to greyish-brown in colour, with a paler underside. Of the two dorsal fins, the first is larger than the second, and each has a short spine, a white rear margin, and a dark blotch towards the front, which is more distinct in juveniles. The large caudal fin is asymmetrical, with a longer upper than lower lobe.
Blurred lanternshark
The blurred lanternshark ("Etmopterus bigelowi") is a little-known species of dogfish shark in the family Etmopteridae, found around the world in benthic and pelagic habitats from a depth of to over down. This shark forms the "E. pusillus" species group with the smooth lanternshark, which are distinguished from other members of its family by having irregularly arranged, flat-topped dermal denticles that give them a "smooth" appearance. Both species are slender-bodied with long heads, two dorsal fins bearing spines, no anal fins, and light-emitting photophores. The blurred lanternshark is larger, reaching or more in length. This species feeds on small squid, fishes, and fish eggs, and is ovoviviparous. It has been assessed as of Least Concern by the International Union for Conservation of Nature, because of its wide distribution and lack of threat from fishing pressure.
Dusky sergeant
The dusky sergeant ("Abudefduf concolor"), or night sergeant is a damselfish endemic to the eastern Pacific Ocean.
Milk shark
The milk shark is harmless to humans because of its small size and teeth. Caught using longlines, gillnets, trawls, and hook-and-line, this shark is marketed fresh or dried and salted for human consumption, and is also used for shark fin soup and fishmeal. Its abundance makes it a significant component of artisanal and commercial fisheries across its range. Off northern Australia, it ranks among the most common sharks caught in trawls, and comprises 2% and 6% of the annual gillnet and longline catches, respectively. This species is also one of the most commercially important sharks caught off Senegal, Mauritania, Oman, and India. Some sport fishers regard it as a game fish.
Aipysurus duboisii
Aipysurus duboisii, also known as the Dubois' sea snake or reef shallows sea snake, is a species of venomous sea snake. Its geographic range includes Papua New Guinea, New Caledonia and the northern, eastern and western coastal areas of Australia, that is the Coral Sea, Arafura Sea, Timor Sea and Indian Ocean. They live at depths up to 80 meters (262 feet) in coral reef flats, sandy and silty sediments which contain seaweed, invertebrates and corals or sponges that can serve as shelter. These snakes feed on moray eels and various fish that live on the seafloor, up to 110 cm (3.6 feet) in size. They are viviparous, giving birth to live young rather than laying eggs. They have medium aggressiveness, i.e., will bite if provoked, but not spontaneously. The fangs are 1.8 mm long, which are relatively short for a snake, and the venom yield is 0.43 mg. "Aipysurus duboisii" is a crepuscular species, meaning that they are most active at dawn and dusk.
Dusky shiner
The dusky shiner ("Notropis cummingsae") is a species of cyprinid fish in the genus "Notropis". It is endemic to the United States, where it is found in the lower Tar River drainage, North Carolina, south to Altamaha River drainage in Georgia, the St. Johns River drainage in Florida, and the Aucilla River drainage to Choctawhatchee River drainage, Florida, Georgia, and Alabama.
Rainbow shark
The rainbow shark ("Epalzeorhynchos frenatum") is a species of Southeast Asian freshwater fish from the family Cyprinidae. It is also variously known as the ruby shark, red-fin shark, red-finned shark, rainbow sharkminnow, green fringelip labeo, whitefin shark and whitetail sharkminnow. It is a popular, semi-aggressive aquarium fish. Unlike true sharks, which belong to the Chondrichthyes ("cartilagenous fishes") lineage, the rainbow shark is an actinopterygiian ("ray-finned fish").
Blackspot shark
The blackspot shark feeds on small fish, crustaceans, and squid, and is not dangerous to man. It is a fast-growing, short-lived species. It is mature at about one year old at a length around and can live for five years or more. Like other members of its genus, the blackspot shark is viviparous. The gestation period is about 9 months and one or two offspring develop at one time in the uterus. At first, the embryos are sustained by a yolk sac, but later a placenta develops. Off the coast of Natal, the juvenile sharks are born in spring.
Smallfin gulper shark
Smallfin gulpers are common deepwater sharks. They live near the bottom between 130 and 820 m. They are ovoviviparous and have two pups per litter. Their diets are primarily bony fish, but also other sharks, molluscs, crustaceans, and even tunicates are consumed.
Blind shark
The range of the blind shark is restricted to the eastern coast of Australia, from Mooloolaba in southern Queensland to Jervis Bay in New South Wales; past reports from off Western Australia and Northern Territory appear to be misidentifications of the brownbanded bamboo shark. The blind shark is a bottom-dwelling species that generally inhabits the continental shelf from the intertidal zone, including tidal pools barely deep enough to cover its body, to a depth of , though it has been recorded as deep as . Preferred habitats are rocky areas and adjacent seagrass beds; juveniles are common in high-energy surge zones. In Nelson Bay, this shark has been observed lying in the open atop sponges.
Dusky dolphin
The dusky dolphin has a discontinuous semi-circumpolar range. The dolphins can be found off the coasts of South America, southwestern Africa, southern Australia and Tasmania, New Zealand, and some oceanic islands. Off South America, they range from southern Peru to Cape Horn in the west and from southern Patagonia to around 36°S in the east. Its range also includes the Falkland Islands. They are particularly common from Peninsula Valdes to Mar de Plata. In comparison, they are uncommon in the Beagle Channel and the inshore waters of the Tierra del Fuego region.
Toothed whale
For most of the smaller species of dolphins, only a few of the larger sharks, such as the bull shark, dusky shark, tiger shark, and great white shark, are a potential risk, especially for calves. Dolphins can tolerate and recover from extreme injuries (including shark bites) although the exact methods used to achieve this are not known. The healing process is rapid and even very deep wounds do not cause dolphins to hemorrhage to death. Even gaping wounds restore in such a way that the animal's body shape is restored, and infection of such large wounds are rare.
Dusky shark
In the northwestern Atlantic, around 60% of the dusky shark's diet consists of bony fishes, from over ten families with bluefish ("Pomatomus saltatrix") and summer flounder ("Paralichthys dentatus") being especially important. Cartilaginous fishes, mainly skates and their egg cases, are the second-most important dietary component, while the lady crab ("Ovalipes ocellatus") is also a relatively significant food source. In South African and Australian waters, bony fishes are again the most important prey type. Newborn and juvenile sharks subsist mainly on small pelagic prey such as sardines and squid; older sharks over long broaden their diets to include larger bony and cartilaginous fishes. The run of the southern African pilchard ("Sardinops sagax"), occurring off the eastern coast of South Africa every winter, is attended by medium and large-sized dusky sharks. Pregnant and post-partum females do not join, possibly because the energy cost of gestation leaves them unable to pursue such swift prey. One South African study reported that 0.2% of the sharks examined had preyed upon bottlenose dolphins ("Tursiops truncatus").
Night shark
Night sharks are quick, nocturnally active, schooling predators that feed mainly on small bony fishes and squid. Reproduction is viviparous as with the other members of its family; females mate during the summer and give birth to litters of usually 12–18 pups after a gestation period of a year. This deepwater species is not known to pose a danger to humans. It is caught incidentally by commercial tuna and swordfish longline fisheries in the western Atlantic, and also by a targeted longline fishery operating off northeastern Brazil. The night shark is highly valued for its fins, and additionally as a source of meat, liver oil, and fishmeal. However, most sharks caught off northeastern Brazil have been found to contain unsafe concentrations of mercury.
Dusky shark
French naturalist Charles Alexandre Lesueur published the first scientific description of the dusky shark in an 1818 issue of "Journal of the Academy of Natural Sciences of Philadelphia". He placed it in the genus "Squalus" and gave it the specific epithet "obscurus" (Latin for "dark" or "dim"), referring to its coloration. Subsequent authors have recognized this species as belonging to the genus "Carcharhinus". Lesueur did not designate a type specimen, though he was presumably working from a shark caught in North American waters.
Dusky smooth-hound
The dusky smooth-hound ("Mustelus canis"), also called the smooth dogfish or the dog shark, is a species of houndshark in the family Triakidae. This shark is an olive grey or brown in color, and may have shades of yellow or grayish white. Females live to 16 years and males have a lifespan of 10 years. "M. canis" was the first shark recognised to have viral infections.
Dusky shark
Newborn dusky sharks measure long; pup size increases with female size, and decreases with litter size. There is evidence that females can determine the size at which their pups are born, so as to improve their chances of survival across better or worse environmental conditions. Females also provision their young with energy reserves, stored in a liver that comprises one-fifth of the pup's weight, which sustains the newborn until it learns to hunt for itself. The dusky shark is one of the slowest-growing shark species, reaching sexual maturity only at a substantial size and age (see table). Various studies have found growth rates to be largely similar across geographical regions and between sexes. The annual growth rate is over the first five years of life. The maximum lifespan is believed to be 40–50 years or more.
Dusky darter
All species of "Percina" are carnivorous, most species feeding on aquatic insect larvae such as chironomids (midges), black flies, ephemeropterans (mayflies), and hydropsychids (caddisflies).
Silky shark
The silky shark ("Carcharhinus falciformis"), also known by numerous names such as blackspot shark, grey whaler shark, olive shark, ridgeback shark, sickle shark, sickle-shaped shark and sickle silk shark, is a species of requiem shark, in the family Carcharhinidae, named for the smooth texture of its skin. It is one of the most abundant sharks in the pelagic zone, and can be found around the world in tropical waters. Highly mobile and migratory, this shark is most often found over the edge of the continental shelf down to . The silky shark has a slender, streamlined body and typically grows to a length of . It can be distinguished from other large requiem sharks by its relatively small first dorsal fin with a curving rear margin, its tiny second dorsal fin with a long free rear tip, and its long, sickle-shaped pectoral fins. It is a deep, metallic bronze-gray above and white below.
Whitecheek shark
The whitecheek shark mostly feeds on fish, but also eats octopus, squid, and various crustaceans including crabs. It sometimes picks off molluscs and worms from the seabed.
Gummy shark
Gummy sharks are found to be mostly bottom dwellers in the waters around southern Australia, from Shark Bay in Western Australia to Port Stephens in New South Wales, from the surface down to a depth of 350 metres in moderate-temperature water. The reproduction of the single-sex school gummy sharks is ovoviviparous. Ovoviviparous organisms are those who produce young via egg and hatched inside of the parents' bodies. A common example of an ovoviviparous being is a seahorse. Females can have up to 57 pups per litter and are ready to do so by the age of five. The average number of pups per litter birthed by the female Mustelus antarcticus is 14 but can have up to 57. Male sharks are ready to reproduce by the age of four. Gestation takes approximately one year. The typical generation length for the gummy shark is 10 years and have an average life expectancy of 16 years. These sharks pose no known threat to beach goers or fisherman. This species is also of least concern in terms of endangerment according to the IUCN Red List is an extensive list of species and where they fall on the endangered scale from “Least concern” (LC) to “Extinct” (EX).
Blind shark
The blind shark is basically harmless to humans, though it can bite if provoked and is difficult to remove, owing to its strong jaws and powerful suction. There are cases of blind sharks biting and holding onto divers' wetsuits even after they surfaced, and could only be removed by prying open the sharks' jaws. This species is one of the few sharks considered suitable for private aquaria, as it is hardy, grows to a small size, and has sedentary habits, though its nocturnal, reclusive nature make it difficult to observe. The blind shark has even been induced to breed in captivity, with the Sydney Aquarium having successfully maintained a breeding colony.
Tiger shark
The tiger shark is an apex predator and has a reputation for eating almost anything. These predators swim close inland to eat at night, and during the day swim out into deeper waters. Young tiger sharks are found to feed largely on small fish, as well as various small jellyfish, and mollusks including cephalopods. Around the time they attain , or near sexual maturity, their selection expands considerably, and much larger animals become regular prey. Numerous fish, crustaceans, sea birds, sea snakes, marine mammals (e.g. bottlenose dolphins ("Tursiops"), common dolphins ("Delphinus"), spotted dolphins ("Stenella"), dugongs ("Dugong dugon"), seals and sea lions, and sea turtles (including the three largest species: the leatherback ("Dermochelys coriacea"), the loggerhead ("Caretta caretta") and the green sea turtles ("Chelonia mydas"),) are regularly eaten by adult tiger sharks. In fact, adult sea turtles have been found in up to 20.8% of studied tiger shark stomachs, indicating somewhat of a dietary preference for sea turtles where they are commonly encountered. They also eat other sharks (including adult sandbar sharks ("Carcharhinus plumbeus")), as well as rays, and sometimes even other tiger sharks.
Platycephalus fuscus
The dusky flathead or black flathead ("Platycephalus fuscus") (literally translating from Ancient Greek as ""flat-head dusky"") is a large predatory fish and the largest member of the family Platycephalidae. Dusky flathead are a largely estuarine species and are found in estuaries, estuarine lakes and coastal bays on the east coast of Australia, from Cairns in Queensland to the Gippsland Lakes in Victoria. They occur over sand, mud, gravel and seagrass and can inhabit estuarine waters up to the tidal limit.
Nervous shark
The diet of the nervous shark consists mainly of small teleost fishes (including silversides, smelt-whitings, wrasses, and grunters). Crustaceans (including prawns, crabs, and mantis shrimps) and molluscs (predominantly cephalopods but also bivalves and gastropods) constitute secondary food sources. This shark is also known to occasionally prey on the semiaquatic snakes "Cerberus rynchops" and "Fordonia leucobalia". A known parasite of the nervous shark is the myxosporean "Kudoa carcharhini".
Blind shark
The blind shark ("Brachaelurus waddi") is one of two species of carpet sharks in the family Brachaeluridae, along with the bluegrey carpetshark ("Brachaelurus colcloughi"). Found along the coast of eastern Australia, this nocturnal, bottom-dwelling species is common in rocky areas and seagrass beds from the intertidal zone to a depth of . It often roams in tidal pools where it may be trapped by the receding tide, and can survive for an extended period out of water. The blind shark is not actually blind; its common name came from its habit of closing its eyes when taken out of the water.
Dusky dolphin
Dusky dolphins prey on a variety of fish and squid species. Common fish species eaten include anchovies, lantern fish, pilchards, sculpins, hakes, horse mackerel, hoki and red cod. They are generally coordinated hunters. Their very flexible foraging strategies can change depending on the environment. In certain parts of New Zealand, where deep oceanic waters meet the shore, dusky dolphins forage in deep scattering layers at night. They arrive at the hunting site individually, but form groups when in the layer. The dolphins use their echolocation to detect and isolate an individual prey. Groups of foraging dolphins tend to increase when the layer is near the surface and decrease when it descends.
Smooth lanternshark
The smooth lanternshark or slender lanternshark ("Etmopterus pusillus") is a species of dogfish shark in the family Etmopteridae, found widely in the Atlantic and Pacific Oceans. It inhabits benthic environments at a depth of , and pelagic environments at a depth of . The smooth lanternshark forms a species group with the larger blurred lanternshark ("E. bigelowi"), both of which are distinguished from other members of their family by small, irregularly arranged dermal denticles with a truncated shape. This species has a slender, dark brown body with an indistinct black band on the sides over the pelvic fins, and reaches in length. This slow-growing, ovoviviparous shark feeds on smaller squid, fishes, and fish eggs. Smooth lanternsharks are often caught as bycatch in eastern Atlantic and Japanese commercial fisheries. The International Union for Conservation of Nature (IUCN) has evaluated this species as of Least Concern because of its wide distribution and limited threats.
Dusky shark
Like other requiem sharks, the dusky shark is viviparous: the developing embryos are initially nourished by a yolk sac, which is converted into a placental connection to the mother once the yolk supply is exhausted. Mating occurs during spring in the northwestern Atlantic, while there appears to be no reproductive seasonality in other regions such as off South Africa. Females are capable of storing masses of sperm, possibly from multiple males, for months to years within their nidamental glands (an organ that secretes egg cases). This would be advantageous given the sharks' itinerant natures and low natural abundance, which would make encounters with suitable mates infrequent and unpredictable.
Swell shark
Swell sharks hunt at night for bony fish, molluscs, and crustaceans. They will eat prey that is dead or alive. They feed either by sucking prey into their mouth or by waiting motionless on the sea floor with their mouth open, waiting to encounter prey. Swell sharks have also been known to look for food in lobster traps.
Blotchy swellshark
Like other members of its genus, when threatened the blotchy swellshark is capable of rapidly inflating its stomach with water or air. This allows the shark to wedge itself inside a rocky crevice, becoming extremely difficult to remove. This species is an opportunistic, highly voracious predator; one recorded female long had 10 fish about long and 15 squid about long in her stomach. Predominantly piscivorous, this species is known to prey upon hagfish and at least 50 species of bony fishes, including fast-swimming types that inhabit open water; significant prey species include the mackerel "Scomber japonicus", the sardine "Sardinops melanostictus", the filefish "Thamnaconus modestus", and the hakeling "Physiculus japonicus". Unusually for such a small shark, it also feeds on at least 10 species of cartilaginous fishes, including lantern sharks, catsharks (particularly the cloudy catshark, "Scyliorhinus torazame", and its eggs), the electric ray "Narke japonica", and skates (including their eggs). It also cannibalizes smaller members of its own species. Cephalopods, mostly the squid "Doryteuthis bleekeri" and the cuttlefish "Sepia" spp., are also frequently taken, while crabs, shrimp, and isopods are occasionally consumed. The dietary composition of juveniles varies notably from place to place.
Blind shark
The pectoral fins are large and broad, with rounded margins. The two dorsal fins are roughly equal in size and have rounded apices and angular free rear tips; the first dorsal fin originates over the bases of the pelvic fins. The pelvic fins are rounded and almost as large as the pectoral fins. The anal fin is less than half the size of the dorsal fins and is positioned very close to the base of the long, low caudal fin. The caudal fin comprises about a quarter of the total length, with no ventral lobe and a strong ventral notch near the tip of the upper lobe. The dermal denticles are large, giving the skin a rough texture. This species is light to dark brown above, often with white flecks, and lighter below. Juveniles also have dark bands over the body and tail, which fade with age. The blind shark can reach a length of , though most are much smaller.
Somniosidae
Beaks recovered from the stomachs of sleeper sharks suggest that these sharks feed on giant squid and colossal squid. This makes sleeper sharks the second known animal that preys on these squid, alongside the sperm whale.Greenland sharks of the family Somniosidae are hunted for food in Iceland. In modern times, many Greenlandic sharks used for hákarl production are purchased from fishing ships where the sharks were trapped in the fishing nets. The shark carcass is traditionally fermented in a shallow pit, with stones placed on top of the shark, allowing poisonous internal fluids, like urea and trimethylamine oxide, to be pressed and drained out of the body. The meat is then cured for several months, rendering it safe for human consumption.
Daggernose shark
The daggernose shark poses little danger to humans due to its small size and teeth. This shark is caught in small numbers by subsistence fishers in Trinidad, Guyana, Suriname, and French Guiana. It also comprises about one-tenth of the catch of a northern Brazil floating gillnet fishery targeting Serra Spanish mackerel ("Scomberomorus brasiliensis") and Acoupa weakfish ("Cynoscion acoupa"), which operates in estuaries during the dry season. This shark is often found in markets, but is not highly regarded as a food fish. The International Union for Conservation of Nature (IUCN) has assessed this species as Critically Endangered, as it has a limited distribution and is highly susceptible to overfishing due to its low reproductive rate. The daggernose shark has declined over 90% over the past decade off Brazil, and similar declines have likely also occurred elsewhere in its range as fishing pressure in the region continues to grow more intense. The IUCN has urgently recommended the implementation of conservation schemes and the expansion of fishery monitoring for this species. Evidence also points to this species being on the verge of or already in reproductive collapse.
Rainbow shark
Rainbow sharks are tank-bottom and aquarium-surface cleaners. Being bottom- and mid-level dwellers, they consume leftover fish food, but also eat the algae growing off surfaces. They are known to be peaceful with their own kind in the wild, but have been known to be aggressive with one another if kept together in a tank. Threat displays and fighting are likely to occur. This fighting behavior involves head-and-tail butting, and also biting.. A large rainbow shark will continuously chase a smaller one until the smaller one dies, or chase other fish out of its territory, especially in confined environments like aquaria. It may also increase the risk of the fish jumping out of its tank. This makes breeding difficult. Provision of hiding places and hollowed decors such as plants or artificial cave-like and tunnel-like aquatic ornaments minimize this typical behavior. Due to this behavioral characteristic among its own kind, rainbow sharks are not recommendable to the new aquarist. Keeping them with relatives, such as red-tailed sharks, bala sharks and black sharks should be avoided, as they will chase and attack them as well.
Dusky shark
The dusky shark is nomadic and strongly migratory, undertaking recorded movements of up to ; adults generally move longer distances than juveniles. Sharks along both coasts of North America shift northward with warmer summer temperatures, and retreat back towards the equator in winter. Off South Africa, young males and females over long disperse southward and northward respectively (with some overlap) from the nursery area off KwaZulu-Natal; they join the adults several years later by a yet-unidentified route. In addition, juveniles spend spring and summer in the surf zone and fall and winter in offshore waters, and as they approach in length begin to conduct a north-south migration between KwaZulu-Natal in the winter and the Western Cape in summer. Still-larger sharks, over long, migrate as far as southern Mozambique. Off Western Australia, adult and juvenile dusky sharks migrate towards the coast in summer and fall, though not to the inshore nurseries occupied by newborns.
Silky shark
The skin is densely covered by minute, overlapping dermal denticles. Each dermal denticle is diamond-shaped and bears horizontal ridges leading to posterior marginal teeth, which increase in number as the shark grows. The back is metallic golden-brown to dark gray and the belly is snowy white, which extends onto the flank as a faint lighter stripe. The fins (except for the first dorsal) darken at the tips; this is more obvious in young sharks. The coloration quickly fades to a dull gray after death. One of the larger members of its genus, the silky shark commonly reaches a length of , with a maximum recorded length and weight of and , respectively. Females grow larger than males.
Port Jackson shark
Digestion of food can take a long time in the Port Jackson shark. Food moves from the mouth to the J-shaped stomach, where it is stored and initial digestion occurs. Unwanted items may never get any further than the stomach, and are coughed up again. They have the ability to turn their stomachs inside out and spit it out of their mouths to get rid of any unwanted contents. One of the biggest differences in digestion in the shark when compared to mammals is the extremely short intestine. This short length is achieved by the spiral valve with multiple turns within a single short section instead of a very long tube-like intestine. The valve provides a very long surface area for the digestion of food, requiring it to pass around inside the apparently short gut until fully digested, when remaining waste products pass by. The most obvious internal organ in sharks is the huge liver, which often fills most of the body cavity. Dietary items include sea urchins, molluscs, crustaceans, and fishes. Black sea urchins ("Centrostephanus rodgersii") are often eaten. Port Jackson Sharks forage for food at night when their prey are most active. They often use caves and rocky outcrops as protection during the day.
Crocodile shark
With a long body, small fins, and large liver rich in squalene and other low-density lipids, the crocodile shark is convergently similar to mesopelagic dogfish sharks such as the cookiecutter shark ("Isistius brasiliensis"). The liver may comprise a fifth of the shark's weight, and acts as an incompressible float that allows it to maintain neutral buoyancy in the water column with little effort. Like many other inhabitants of the mesopelagic zone, the crocodile shark apparently migrates closer to the surface at night to feed and descends into deeper water during the day, being rarely found above a depth of 200 m (660 ft) during daytime.
Broadnose sevengill shark
An opportunistic predator, the broadnose sevengill preys on a great variety of animals and has been found at a depth of in offshore waters. It has been found to feed on sharks (including gummy shark, one of its main prey, and cowsharks), rays, chimaeras, cetaceans, pinnipeds, bony fishes and carrion and will also feed on whatever it finds such as shark egg cases, sea snails and remains of rats and humans. Research in 2003 found that its diet consisted of 30% mammals with a frequency of occurrence of 35%. It is a frequent top predator in shallow waters and has comb-like teeth, with the upper teeth having slender, smooth edged cusps to swallow small enough prey whole and lower teeth broad enough to bite prey to pieces. These sharks occasionally hunt in packs to take down larger prey, using tactics such as stealth to succeed. After feeding, it slowly digests the food for several hours and days and can go weeks until eating again. Large predatory sharks such as the great white shark can be a threat and cannibalism among this shark has also been recorded. When not highly active, it hunts stealthily while making very little movement except for moving its caudal fin until dashing to strike.
Zeidae
Predators of dories include large sharks such as the dusky shark ("Carcharhinus obscurus") and other requiem sharks, and larger shelf- and slope-dwelling bony fish, such as predatory Moehau, and merluccid hakes.
Blacknose shark
The first dorsal fin is small and somewhat sickle-shaped, with a pointed apex and a short, free, rear tip; its origin lies over the free rear tips of the pectoral fins. The second dorsal fin is relatively large, though still less than half the height of the first. No ridge is seen between the dorsal fins. The pectoral fins are short and tapered. The body is covered with overlapping dermal denticles that bear five to seven longitudinal ridges (three in very young individuals) leading to three to five marginal teeth. The coloration is yellowish to greenish-gray or brown above and white to yellow below. A distinctive dark blotch at the tip of the snout is most obvious in young sharks. The tips of the second dorsal fin, upper caudal fin lobe, and sometimes the lower caudal fin lobe, are dark. Blacknose sharks are typically long and in weight. The maximum length and weight on record is and , respectively.
A small, fast-swimming predator, the blacknose shark feeds primarily on small, bony fishes, including pinfish, croakers, porgies, anchovies, spiny boxfish, and porcupinefish, as well as on octopus and other cephalopods. When competing for bait, their speed allows them to snatch food from larger sharks such as the Caribbean reef shark ("C. perezi"). This species may form large schools that are sometimes associated with anchovies and mullet. Blacknose sharks demonstrate a high degree of philopatry: both juveniles and adults have been documented returning to the same local area year after year.
Dumb gulper shark
The dumb gulper shark ("Centrophorus harrissoni") is a rare and endangered deepwater dogfish, known from only along the east coast of Australia and isolated spots north and west of New Zealand. It is also known as the dumb shark, Harrison's deep-sea dogfish, or Harrison's dogfish.
Hungry Shark
"Hungry Shark" revolves around the player, a lone shark, consuming various marine species to grow in size until the subsequent, more powerful sharks are unlocked. The number of species the player is able to consume depends on the strength of the shark; for instance, a reef shark cannot eat lionfish, but a great white shark is able to. Not all creatures can be consumed, and some are hostile towards the shark.
Dusky smooth-hound
Commercial fisheries have had an increased interest in smooth dogfish since the 1900s. They are caught using longlines and bottom trawls primarily off of Massachusetts, New Jersey, Maryland, Virginia, and North Carolina. Mostly, they are considered bycatch when fishing for other species, which has put them in the near-threatened category by the IUCN Red List of Threatened Species. They are no danger to humans because of their blunt teeth.
Tonic immobility has been reported in several cartilaginous fishes, one of which is "M. canis." Tonic immobility is induced by grasping the first dorsal fin with one hand and the body immediately anterior to the anal fin with the other, inverting the shark and holding it rigidly. The mean time to induce tonic immobility in smooth dogfish was 32.5 seconds. The mean duration of the tonic immobility was 61.9 seconds. Sharks that had the “limp” response also exhibited tonic immobility. The “limp” response is a criterion for the onset of tonic immobility.
Dusky catshark
The dusky catshark ("Bythaelurus canescens") is a catshark of the family Scyliorhinidae, found from Peru and Chile to the Straits of Magellan.
Rainbow shark
Rainbow sharks are not picky herbivorous and omnivorous eaters, but are primarily consumers of algae in the form of tablets, wafers and flakes. They also eat live foods, such as insect larvae, tubifex worms, periphyton, crustaceans, phytoplankton, zooplankton and aquatic insects. Diet also include lettuce and spinach. They will also eat frozen bloodworms and brine shrimp.
Oceanic whitetip shark
"C. longimanus" feeds mainly on pelagic cephalopods and bony fish. However, its diet can be far more varied and less selective—it is known to eat threadfins, stingrays, sea turtles, birds, gastropods, crustaceans, and mammalian carrion. The bony fish it feeds on include lancetfish, oarfish, barracuda, jacks, dolphinfish, marlin, tuna, and mackerel. Its feeding methods include biting into groups of fish and swimming through schools of tuna with an open mouth. When feeding with other species, it becomes aggressive. Peter Benchley, author of "Jaws", observed this shark swimming among pilot whales and eating their faeces.
Longfin mako shark
Longfin mako sharks are predators that feed on small schooling bony fishes and cephalopods. Whether this shark is capable of elevating its body temperature above that of the surrounding water like the other members of its family is uncertain, though it possesses the requisite physiological adaptations. Reproduction in this species is aplacental viviparous, meaning the embryos hatch from eggs inside the uterus. In the later stages of development, the unborn young are fed nonviable eggs by the mother (oophagy). The litter size is typically two, but may be as many as eight. The longfin mako is of limited commercial value, as its meat and fins are of lower quality than those of other pelagic sharks; it is caught unintentionally in low numbers across its range. The International Union for Conservation of Nature has assessed this species as vulnerable due to its rarity, low reproductive rate, and continuing bycatch mortality.
Jersey Shore shark attacks of 1916
By the end of July 1916, John Nichols and Robert Murphy were taking the great white more seriously. In "Scientific American", Murphy wrote that the "white shark is perhaps the rarest of all noteworthy sharks ... their habits are little known, but they are said to feed to some extent on big sea turtles ... Judging from its physical make-up, it would not hesitate to attack a man in open water." He concluded that "because it is evident that even a relatively small white shark, weighing two or three hundred pounds, might readily snap the largest human bones by a jerk of its body, after it has bitten through the flesh."
Pacific sleeper shark
Pacific sleeper sharks, which are thought to be both predators and scavengers, can glide through the water with little body movement and little hydrodynamic noise, making them successful stealth predators. They feed by means of suction and cutting of their prey. They have large mouths that can inhale prey and their teeth cut up any pieces that are too large to swallow. They show a characteristic rolling motion of the head when feeding. Only in Alaska has the shark's diet been studied - most sharks' stomachs contain remains of giant Pacific octopus. They are also known to feed on bottom-dwelling teleost fishes, as well as soles, flounders, Alaska pollock, rockfishes, shrimps, hermit crabs, and even marine snails. Larger Pacific sleeper sharks are also found to feed on fast-swimming prey such as squids, Pacific salmon, and harbor porpoises. The diet of the Pacific sleeper shark seems to broaden as they increase in size. For example, a 3.7-m female shark found off Trinidad, California was found to have fed mostly on giant squid. Sleeper sharks found in Alaskan waters from seem to feed mostly on flounder, pollock, and cephalopods, while sleeper sharks long seem to consume teleosts and cephalopods, as well as marine mammals. A recent study in the Gulf of Alaska suggests that sleeper sharks may prey on juvenile Steller sea lions.
Whitespotted bamboo shark
These sharks feed at night, preying on small fish and invertebrates. They have small teeth that can be used for grasping or crushing prey. Soft prey is grasped when the tips of the teeth sink into the flesh, but the teeth pivot backwards when biting hard prey. This protects the tooth tip and allows the flattened front surface of the teeth to form a continuous plate for crushing crabs.
Brown fur seal
The African fur seal's diet is made of up to 70% fish, 20% squid, and 2% crab. Also eaten are other crustaceans, cephalopods and sometimes birds. In rare instances, they have even been documented attacking and eating sharks. A recent incident occurred off Cape Point, South Africa, where a large male was observed attacking and killing five blue sharks between 1.0 and 1.4 m long. Observers concluded that the seal likely killed the sharks to eat the fish-rich contents of their stomachs, as well as their livers as a source of energy. The Australian fur seal mostly eats squid, octopus, fish, and lobsters. The brown fur seal dives for its food. The African subspecies can dive as deep as 204 m and for as long as 7.5 minutes. The Australian subspecies generally feeds at lower depths, diving on average 120 m and can reach as deep as 200 m.
Largetooth cookiecutter shark
The largetooth cookiecutter shark ("Isistius plutodus") is a rare species of squaliform shark in the family Dalatiidae, reported from depths of at scattered locations in the Atlantic and Pacific Oceans. As its common name suggests, it is similar in appearance to the cookiecutter shark ("I. brasiliensis") but has much larger lower teeth. Most individuals also lack the dark "collar" of "I. brasiliensis". This species reaches a maximum known length of . The largetooth cookiecutter shark feeds by gouging out chunks of flesh from larger animals, including bony fishes, sharks, and marine mammals, and is able to take larger bites than "I. brasiliensis". Little is known of its life history; it is thought to be a weaker swimmer than "I. brasiliensis", and is presumably aplacental viviparous like the rest of its family. This shark is an infrequent bycatch of commercial trawl and longline fisheries, but is not thought to be much threatened by these activities.
Yellowspotted catshark
The yellowspotted catshark feeds on small fish, crustaceans and squid. It is an egg-laying species, laying a single egg at a time, and enclosing it in an egg case roughly . The juvenile fish when they hatch may measure about and the adults can grow to but most individuals are under a metre (3 ft) long. This shark is more common on rocky reefs than on sandy seabeds.
Dusky shark
In addition to commercial shark fisheries, dusky sharks are also caught as bycatch on longlines meant for tuna and swordfish (and usually kept for its valuable fins), and by recreational fishers. Large numbers of dusky sharks, mostly juveniles, are caught by sport fishers off South Africa and eastern Australia. This shark was once one of the most important species in the Florida trophy shark tournaments, before the population collapsed.
Dusky snake eel
The Dusky snake eel (Ophichthus cylindroideus, also known as the Tentacle-nose eel) is an eel in the family Ophichthidae (worm/snake eels). It was described by Camillo Ranzani in 1839. It is a tropical, marine eel which is known from the western Atlantic Ocean, including Cuba and Brazil.
Dusky shark
Many early sources gave the scientific name of the dusky shark as "Carcharias" (later "Carcharhinus") "lamiella", which originated from an 1882 account by David Starr Jordan and Charles Henry Gilbert. Although Jordan and Gilbert referred to a set of jaws that came from a dusky shark, the type specimen they designated was later discovered to be a copper shark ("C. brachyurus"). Therefore, "C. lamiella" is not considered a synonym of "C. obscurus" but rather of "C. brachyurus". Other common names for this species include bay shark, black whaler, brown common gray shark, brown dusky shark, brown shark, common whaler, dusky ground shark, dusky whaler, river whaler, shovelnose, and slender whaler shark.
Grey reef shark
Grey reef sharks feed mainly on bony fishes, with cephalopods such as squid and octopus being the second-most important food group, and crustaceans such as crabs and lobsters making up the remainder. The larger sharks take a greater proportion of cephalopods. These sharks hunt individually or in groups, and have been known to pin schools of fish against the outer walls of coral reefs for feeding. Hunting groups of up to 700 grey reef sharks have been observed at Fakarava atoll in French Polynesia. They excel at capturing fish swimming in the open, and they complement hunting whitetip reef sharks, which are more adept at capturing fish inside caves and crevices. Their sense of smell is extremely acute, being capable of detecting one part tuna extract in 10 billion parts of sea water. In the presence of a large quantity of food, grey reef sharks may be roused into a feeding frenzy; in one documented frenzy caused by an underwater explosion that killed several snappers, one of the sharks involved was attacked and consumed by the others.
Ghost Shark
When a great white shark eats the potential catch of a sport fisherman, the man and his daughter violently retaliates by sadistically torturing and killing the shark, whose corpse then sinks to the bottom of an underwater cave and is subsequently resurrected as a ghost shark due to the cave's mysterious paranormal properties. Now hungry for revenge, the ghost shark eats his redneck killers along with the captain of their boat, eventually setting its sights on the rest of the local community in the seaside town of Harmony. Due to the great white's new spectral form, it can attack and kill anyone as long as there is even the smallest amount of water nearby, including coming out of a swimming pool, a bathtub, a bucket, a metal pipe, and even a drinking cup, killing many people in several locations.
Dusky shark
One of the largest members of its genus, the dusky shark commonly reaches a length of and a weight of ; the maximum recorded length and weight are and respectively. Females grow larger than males. This shark has a slender, streamlined body with a broadly rounded snout no longer than the width of the mouth. The nostrils are preceded by barely developed flaps of skin. The medium-sized, circular eyes are equipped with nictitating membranes (protective third eyelids). The mouth has very short, subtle furrows at the corners and contains 13-15 (typically 14) tooth rows on either side of both jaws. The upper teeth are distinctively broad, triangular, and slightly oblique with strong, coarse serrations, while the lower teeth are narrower and upright, with finer serrations. The five pairs of gill slits are fairly long.
Eastern spotted gummy shark
The eastern spotted gummy shark ("Mustelus walkeri") is a species of houndshark in the Triakidae family, found in Australian waters. This new species of gummy sharks is a relatively large species with the following characteristics: tall dorsal fins, its posterior margin directed posteroventrally from top to bottom and not upright distally, first dorsal-fin base is 1.6-2.0 times the anal-caudal space; buccopharyngeal denticles cover entire palate and floor of mouth; long claspers of adult males are slender, strongly depressed, the inner length about 9-10% TL, extending to just anterior of the second dorsal-fin origin; lower edge of spiracle is usually close to level of mid-eye; insertion of anal-fin usually over its apex; about 69/73 teeth rows; 78- 94 precaudal vertebral centra; 35-39 monospondylous centra; dorsal color pale greyish with numerous small, often indistinct, semi-regular, diffuse-edged white spots on postspiracular head and body; light and dark tonal coloration well demarcated on head below eye and onto middle of first gill slit, the intergill membranes are much darker dorsally than ventrally; bases and inner lobe of dorsal fins in juveniles (<400 mm TL) not strongly contrasted to distal part of fin, inner lobe is pale-edged; juveniles have caudal fin with distinctive whitish posterior margins.
Dusky caenolestid
The dusky caenolestid is nocturnal (active mainly at night), and lives on trees. It can be a fast runner, like the Incan caenolestid, though it does not move in leaps and jumps. The dusky caenolestid is reported to have a poor vision, though its sense of smell and hearing are good. Diet consists of lepidopteran larvae, insects, rodents, arachnids and centipedes; plant material may be eaten as well. The tail, though prehensile, may not be able to support the animal when it hangs down a branch.
Velvet belly lanternshark
The velvet belly's liver accounts for 17% of its body mass, three-quarters of which is oil, making it nearly neutrally buoyant. To deal with the higher concentrations of heavy metals in the deep sea, the velvet belly has T-cells in its bloodstream that can identify and mark toxic compounds for elimination. These T-cells are produced by a lymphomyeloid gland in its esophagus called a "Leydig's organ", which is also found in some other sharks and rays. In its liver, specialized proteins are also capable of detoxifying cadmium, copper, mercury, zinc, and other toxic contaminants. The velvet belly's bioluminescence is thought to function in counter-illumination, which eliminates the shark's silhouette and camouflages it from upward-looking predators. Its bioluminescence may also serve a social function, such as finding mates or co-ordinating groups, as the pattern is species-specific. The velvet belly is an important food of larger fishes such as other sharks; a major predator of this species is the longnosed skate ("Dipturus oxyrinchus").
Numerous parasites are known for this species, and both juveniles and adults often carry heavy parasite loads. Known internal parasites include the monogenean "Squalonchocotyle spinacis", the tapeworms "Aporhynchus norvegicus", "Lacistorhynchus tenuis", and "Phyllobothrium squali", and the nematodes "Anisakis simplex" and "Hysterothylacium aduncum". Some of these parasites use the velvet belly's prey as intermediate hosts and are acquired via ingestion, while others use the shark itself as an intermediate host. The barnacle "Anelasma squalicola", an external parasite, attaches to the shark's dorsal spine socket and penetrates deeply into the muscle, in the process often providing an attachment site for a second (and rarely a third) barnacle. Infestation by this barnacle reduces its host's fecundity by impairing the development of the reproductive organs.
Cookiecutter shark
Best known for biting neat round chunks of tissue from marine mammals and large fish, the cookiecutter shark is considered a facultative ectoparasite, as it also wholly ingests smaller prey. It has a wide gape and a very strong bite, by virtue of heavily calcified cranial and labial cartilages. With small fins and weak muscles, this ambush predator spends much of its time hovering in the water column. To maintain neutral buoyancy, its liver, which can comprise some 35% of its weight, is rich in low-density lipids. As this species has higher skeletal density than "Euprotomicrus" or "Squaliolus", its body cavity and liver are proportionately much larger, and the oil content is much higher. Its large caudal fin allows for a quick burst of speed to catch larger, faster prey that come in range.
Sand tiger shark
The sand tiger shark is a nocturnal feeder. During the day, they take shelter near rocks, overhangs, caves and reefs often at relatively shallow depths (<20 m). This is the typical environment where divers encounter sand tigers, hovering just above the bottom in large sandy gutters and caves. However, at night they leave the shelter and hunt over the ocean bottom, often ranging far from their shelter. Sand tigers hunt by stealth. It is the only shark known to gulp air and store it in the shark's stomach, allowing the shark to maintain near-neutral buoyancy which helps it to hunt motionlessly and quietly. Aquarium observations indicate that when it comes close enough to a prey item, it grabs with a quick sideways snap of the prey. The sand tiger shark has been observed to gather in hunting groups when preying upon large schools of fish.
Dusky shark
Full-grown dusky sharks have no significant natural predators. Major predators of young sharks include the ragged tooth shark ("Carcharias taurus"), the great white shark ("Carcharodon carcharias"), the bull shark ("C. leucas"), and the tiger shark ("Galeocerdo cuvier"). Off KwaZulu-Natal, the use of shark nets to protect beaches has reduced the populations of these large predators, leading to a dramatic increase in the number of juvenile dusky sharks (a phenomenon called "predator release"). In turn, the juvenile sharks have decimated populations of small bony fishes, with negative consequences for the biodiversity of the local ecosystem.
Dusky dolphin
The dusky dolphin, protected in much of its range, is listed as Data Deficient by the IUCN because; "... assessment of global population status is not possible with the currently available estimates of abundance and removals. The subpopulation off Peru has probably been overexploited, but present data do not allow estimation of present decline". Dusky dolphins may fall victim to the small cetacean fisheries of Peru and Chile. The expansion of these fisheries could have started in Peru when the anchoveta fishery collapsed in 1972. Dolphins have also been caught in gill nets in New Zealand, but catches appear to have dropped since the 1970s and 1980s. In Peru, dusky dolphins are killed in large numbers (10.000-15.000 per year) and used as shark bait or for human consumption. The dolphins are also thought to have been harpooned off South Africa, but the numbers are not considered large.
Shark
Other sharks feed on squid or fish, which they swallow whole. The viper dogfish has teeth it can point outwards to strike and capture prey that it then swallows intact. The great white and other large predators either swallow small prey whole or take huge bites out of large animals. Thresher sharks use their long tails to stun shoaling fishes, and sawsharks either stir prey from the seabed or slash at swimming prey with their tooth-studded rostra.
Dusky shark
In 1982, Jack Garrick published a phylogenetic analysis of "Carcharhinus" based on morphology, in which he placed the dusky shark and the Galapagos shark ("C. galapagensis") at the center of the "obscurus group". The group consisted of large, triangular-toothed sharks with a ridge between the dorsal fins, and also included the bignose shark ("C. altimus"), the Caribbean reef shark ("C. perezi"), the sandbar shark ("C. plumbeus"), and the oceanic whitetip shark. This interpretation was largely upheld by Leonard Compagno in his 1988 phenetic study, and by Gavin Naylor in his 1992 allozyme sequence study. Naylor was able to further resolve the interrelationships of the "ridge-backed" branch of "Carcharhinus", finding that the dusky shark, Galapagos shark, oceanic whitetip shark, and blue shark ("Prionace glauca") comprise its most derived clade.
Longsnout dogfish
This shark lives at depths between 150 and 732 m. It eats bony fish.
Dusky shark
Teeth belonging to the dusky shark are fairly well represented in the fossil record, though assigning "Carcharhinus" teeth to species can be problematic. Dusky shark teeth dating to the Miocene (23-5.3 Ma) have been recovered from the Kendeace and Grand Bay formations in Carriacou, the Grenadines, the Moghra Formation in Egypt, Polk County, Florida, and possibly Cerro La Cruz in northern Venezuela. Teeth dating to the Late Miocene or Early Pliocene (11.6-3.6 Ma) are abundant in the Yorktown Formation and the Pungo River, North Carolina, and from the Chesapeake Bay region; these teeth differ slightly from the modern dusky shark, and have often been misidentified as belonging to the oceanic whitetip shark ("C. longimanus"). Dusky shark teeth have also been recovered from the vicinity of two baleen whales in North Carolina, one preserved in Goose Creek Limestone dating to the Late Pliocene ("c." 3.5 Ma), and the other in mud dating to the Pleistocene-Holocene ("c." 12,000 years ago).
Dusky smooth-hound
"M. canis" feeds mostly on crustaceans, polychaetes, and mollusks. Smooth dogfish also eat squid, worms, small fish, razor clams, and occasionally garbage. They are nocturnal scavengers and opportunistic predators. Their nocturnal activity helps them to take advantage of concentrations of crustacean prey.
Galapagos shark
Garrick (1982) placed the Galapagos shark and the dusky shark at the center of the "obscurus group", one of two major groupings within "Carcharhinus". The group consisted of the bignose shark ("C. altimus"), Caribbean reef shark ("C. perezi"), sandbar shark ("C. plumbeus"), dusky shark ("C. obscurus"), and oceanic whitetip shark ("C. longimanus"), all large, triangular-toothed sharks and is defined by the presence of a ridge between the two dorsal fins. Based on allozyme data, Naylor (1992) reaffirmed the integrity of this group, with the additions of the silky shark ("C. falciformis") and the blue shark ("Prionace glauca"). The closest relatives of the Galapagos shark were found to be the dusky, oceanic whitetip, and blue sharks.
Dusky spinefoot
The dusky spinefoot ("Siganus luridus") is a species of rabbitfish (Siganidae). It is native to the western Indian Ocean, as well as the Red Sea and Persian Gulf. It has spread to the Mediterranean Sea because of the Suez Canal (Lessepsian migration). It is often found in small schools feeding on benthic algae in shallow water with compacted sand substrates. Its dorsal and anal fin spines contain venom that is not life-threatening to humans.
Brown shyshark
The brown shyshark or plain happy ("Haploblepharus fuscus") is a species of catshark, part of the family Scyliorhinidae. It is endemic to the shallow, coastal waters of South Africa from west of Cape Agulhas to KwaZulu-Natal. This benthic species is usually found over sandy or rocky bottoms. Measuring up to long, the brown shyshark is stoutly built, with a broad, flattened head and rounded snout. Unlike other shysharks, the brown shyshark has a plain brown color, though some individuals have faint "saddle" markings or light or dark spots. When threatened, this shark curls into a circle with its tail over its eyes, which is the origin of the name "shyshark". It feeds on bony fishes and lobsters, and is oviparous with females laying pairs of egg capsules. The International Union for Conservation of Nature (IUCN) has assessed this harmless species as Vulnerable. It is of no commercial or recreational interest, but its limited distribution makes its entire population vulnerable to increases in fishing pressure or habitat degradation.
Ducie Island
In the lagoon there are around 138 fish species, which also inhabit southeastern Oceania, the Western Pacific and the Indian Ocean. The lagoon is noted for its poisonous fishes and dangerous sharks. The yellow-edged lyretail, the blacktip grouper, and the greasy grouper are known to cause ciguatera poisoning. The lagoon is also inhabited by Galápagos sharks and the whitetip reef shark. The Galápagos shark is dangerous to humans, while the whitetips are seldom aggressive unless provoked. Five species are found exclusively around the Pitcairn Islands: "Sargocentron megalops" (a species of squirrelfish), the spiny butterflyfish, the "Henderson triplefin" (a species of threefin blenny), an unnamed species of "Alticus" (a genus of combtooth blenny) and an unnamed species of "Ammodytes" (a genus of sand lance).
Dusky shark
The known diet of the dusky shark encompasses pelagic fishes, including herring and anchovies, tuna and mackerel, billfish, jacks, needlefish and flyingfish, threadfins, hairtails, lancetfish, and lanternfish; demersal fishes, including mullets, porgies, grunts, and flatheads, eels, lizardfish, cusk eels, gurnards, and flatfish; reef fishes, including barracudas, goatfish, spadefish, groupers, scorpionfish, and porcupinefish; cartilaginous fishes, including dogfish, sawsharks, angel sharks, catsharks, thresher sharks, smoothhounds, smaller requiem sharks, sawfish, guitarfish, skates, stingrays, and butterfly rays; and invertebrates, including cephalopods, decapod crustaceans, barnacles, and sea stars. Very rarely, the largest dusky sharks may also consume sea turtles, marine mammals (mainly as carrion), and human refuse.
Sardine run
Swells dropped to 1–1.5 m on 28 June 2011, allowing more netting of sardines. Sardines were netted at Amanzimtoti; on the main beach and at Chain Rocks. A 22-year-old American marine biology student (research diver) named Paulo Edward Stanchi was attacked by a large dusky shark while diving at Aliwal Shoal Marine Protected Area. The group of divers had encountered a pocket of sardines when a 3 m long dusky shark bit Mr Stanchi on his left leg and hands. Mr Stanchi managed to free himself from the shark, and was treated on the diving boat before being transported to Rocky Bay, where medics stabilised him. He was then airlifted to Nkosi Albert Luthuli Hospital, where he underwent surgery. Dusky sharks generally live offshore, but come closer to the shore during the sardine run. The annual sardine run allowed more dusky sharks in the Aliwal Shoal MPA than usual, but there was no reason for them to show any more interest in divers than usual. Mr Stanchi had been wearing split fins with black and grey stripes, and this may have looked like a small shoal of fish to the shark. Meanwhile, a woman in her 40s broke her leg in the frenzy at Amanzimtoti when the sardines were netted. The woman is believed to have been trying to get some of the sardines when she "stepped wrong" and fractured her leg. Paramedics stabilized her before transporting her to hospital.
Great white shark
Great white sharks are carnivorous and prey upon fish (e.g. tuna, rays, other sharks), cetaceans (i.e., dolphins, porpoises, whales), pinnipeds (e.g. seals, fur seals, and sea lions), sea turtles, sea otters ("Enhydra lutris") and seabirds. Great whites have also been known to eat objects that they are unable to digest. Juvenile white sharks predominantly prey on fish, including other elasmobranchs, as their jaws are not strong enough to withstand the forces required to attack larger prey such as pinnipeds and cetaceans until they reach a length of or more, at which point their jaw cartilage mineralizes enough to withstand the impact of biting into larger prey species. Upon approaching a length of nearly , great white sharks begin to target predominantly marine mammals for food, though individual sharks seem to specialize in different types of prey depending on their preferences. They seem to be highly opportunistic. These sharks prefer prey with a high content of energy-rich fat. Shark expert Peter Klimley used a rod-and-reel rig and trolled carcasses of a seal, a pig, and a sheep from his boat in the South Farallons. The sharks attacked all three baits but rejected the sheep carcass.
Brown lanternshark
The brown lanternshark or bristled lanternshark ("Etmopterus unicolor") is a little-known species of deep-sea dogfish shark in the family Etmopteridae. It is found off Japan and New Zealand, and possibly also South Africa and Australia, typically deeper than . This species can be distinguished from other lanternsharks by its coloration, which is a uniform dark gray or brown without the ventral surface being much darker and clearly delineated from the rest of the body. The brown lanternshark feeds on small bony fishes, cephalopods, and crustaceans. Reproduction is ovoviviparous, with females giving birth to 9–18 young. An unusually high proportion of individuals in Suruga Bay are hermaphrodites, with both male and female characteristics.
Dusky sole
The dusky sole, "Lepidopsetta mochigarei", is a flatfish of the family Pleuronectidae. It is a demersal fish that lives on bottoms in the temperate waters of the northwest Pacific, from the Korean peninsula to the southern Sea of Okhotsk. It grows up to in length.
Ginglymostomatidae
Nurse sharks are nocturnal animals, spending the day in large inactive groups of up to 40 individuals. Hidden under submerged ledges or in crevices within the reef, the nurse sharks seem to prefer specific haunts and will return to them every day. By night, the sharks are largely solitary; they spend most of their time searching through the bottom sediments in search of food. Their diet consists primarily of crustaceans, molluscs, tunicates, and other fish, particularly stingrays.
Blind shark
Contrary to its common name, the blind shark has "perfectly adequate" vision. It was so named by anglers because it retracts its eyeballs and shuts its thick lower eyelids when removed from the water. This species can live for up to 18 hours out of water, allowing it to survive being stranded by the outgoing tide. The blind shark is secretive and sluggish during the day, with adults usually hiding in caves or under ledges and juveniles inside crevices, though it will take food given the opportunity. At night, it moves out over reefs and seagrass meadows to forage for small invertebrates (including crabs, shrimp, cephalopods, and sea anemones) and bony fishes. Prey items are captured via suction.
The blind shark is aplacental viviparous with a possibly annual reproductive cycle. Females give birth to 7–8 pups during the summer; newborns measure long. Sexual maturity is attained at under a length of for males, and for females. It has lived to 20 years old in captivity. A known parasite of this shark is an undescribed species of tapeworm in the genus "Carpobothrium".
Dusky jawfish
The dusky jawfish (Opistognathus whitehursti) is a species of jawfish native to the western Atlantic Ocean including the Gulf of Mexico and the Caribbean Sea where it is an inhabitant of reefs at depths of from . It can reach a length of TL. This species can also be found in the aquarium trade. The specific name honours Dr. D. D. Whitehurst, a collector of specimens for the Smithsonian Institution, one of which was the type specimen of this species.
Blackspot shark
The blackspot shark can be confused with the whitecheek shark ("Carcharhinus dussumieri"), but that species has a triangular first dorsal fin that is only slightly falcate, and a small second dorsal fin that merely has a dark margin.
Spined pygmy shark
The diet of the spined pygmy shark consists mainly of bony fishes (including the dragonfish "Idiacanthus", the lanternfish "Diaphus", and the bristlemouth "Gonostoma") and squid (including members of the genera "Chiroteuthis" and "Histioteuthis"). Catch records suggest that the spined pygmy shark follows its prey on their diel vertical migrations, spending the day close to a depth of and ascending towards a depth of at night. The ventral photophores of the spined pygmy shark have been theorized to function in counter-illumination, a form of camouflage in which the shark disguises its silhouette from would-be predators by matching the ambient light welling down from above. There is no evidence that this shark swallows its shed teeth like the pygmy and cookiecutter sharks.
Blackspot shark
The blackspot shark is native to the Indian and Pacific Oceans, where it is found on the continental shelves and shallow water around islands from the surf line to depths of about . It is not usually found in estuaries and may be intolerant of low-salinity water. In the Indian Ocean, it is found along the east coast of Africa from South Africa and Madagascar to Kenya. It is present in the water around the Seychelles and Mauritius, and further east, it is present around the coasts of Pakistan, India, and Sri Lanka. In the western Pacific Ocean, it is found along the coasts of Thailand, Vietnam, China, Indonesia, New Guinea, and northern and western Australia. In South Africa, the species seems to be resident, but some increase in numbers occurs during the summer.
Dusky shark
The dusky shark is considered to be potentially dangerous to humans because of its large size, though little is known of how it behaves towards people underwater. As of 2009, the International Shark Attack File lists it as responsible for six attacks on people and boats, three of them unprovoked and one fatal. However, attacks attributed to this species off Bermuda and other islands were probably in reality caused by Galapagos sharks. Shark nets used to protect beaches in South Africa and Australia entangle adult and larger juvenile dusky sharks in some numbers. From 1978 to 1999, an average of 256 individuals were caught annually in nets off KwaZulu-Natal; species-specific data is not available for nets off Australia. Young dusky sharks adapt well to display in public aquariums.
The dusky shark is one of the most sought-after species for shark fin trade, as its fins are large and contain a high number of internal rays (ceratotrichia). In addition, the meat is sold fresh, frozen, dried and salted, or smoked, the skin is made into leather, and the liver oil is processed for vitamins. Dusky sharks are taken by targeted commercial fisheries operating off eastern North America, southwestern Australia, and eastern South Africa using multi-species longlines and gillnets. The southwestern Australian fishery began in the 1940s and expanded in the 1970s to yield 500–600 tons per year. The fishery utilizes selective demersal gillnets that take almost exclusively young sharks under three years old, with 18–28% of all newborns captured in their first year. Demographic models suggest that the fishery is sustainable, provided that the mortality rate of sharks over 2 m (6.6 ft) long is under 4%.
Smooth hammerhead
The second-largest hammerhead shark after the great hammerhead shark, the smooth hammerhead can measure up to long. It is an active predator that takes a wide variety of bony fishes and invertebrates, with larger individuals also feeding on sharks and rays. As in the rest of its family, this shark is viviparous and gives birth to litters of 20–40 pups. A relatively common shark, it is captured, intentionally or otherwise, by many commercial fisheries throughout its range; its fins are extremely valuable for use in shark fin soup. This shark is potentially dangerous and has likely been responsible for a few attacks on humans, though it is less likely to encounter swimmers than other large hammerhead species due to its temperate habitat.
Pigeye shark
Large and formidably toothed, the pigeye shark is regarded as potentially dangerous to humans, though it has not been implicated in any attacks. This species is caught infrequently on longlines and in gillnets, and is used for meat and fins. As a predator, though, the shark can accumulate ciguatera toxins produced by dinoflagellates within its tissues. In November 1993, some 500 people in Manakara, Madagascar, were poisoned, 98 of them fatally, after eating meat from a pigeye shark. This was the first recorded mass ciguatera outbreak caused by a shark, as well as the first with a significant death toll. The IUCN has listed the pigeye shark overall as Data Deficient, while noting that its rarity may render it susceptible to overfishing. In KwaZulu-Natal, South Africa, small numbers of pigeye sharks are caught in shark nets set up to protect beaches. The catch rate and the average size of sharks caught both decreased between 1978 and 1998, leading to concerns that the local population may be depleted. Thus, the IUCN has given this species a regional assessment of Near Threatened in the southwestern Indian Ocean.
Sand tiger shark
Despite its fearsome appearance and strong swimming ability, it is a relatively placid and slow-moving shark with no confirmed human fatalities. This species has a sharp, pointy head, and a bulky body. The sand tiger's length can reach . They are grey with reddish-brown spots on their backs. Shivers (groups) have been observed to hunt large schools of fish. Their diet consists of bony fish, crustaceans, squid, skates and other sharks. Unlike other sharks, the sand tiger can gulp air from the surface, allowing it to be suspended in the water column with minimal effort. During pregnancy, the most developed embryo will feed on its siblings, a reproductive strategy known as intrauterine cannibalism i.e. "embryophagy" or, more colorfully, adelphophagy — literally "eating one's brother". The sand tiger is categorized as vulnerable on the International Union for Conservation of Nature Red List. It is the most widely kept large shark in public aquariums owing to its tolerance for captivity.
Stegastes fuscus
The dusky damselfish is a territorial species. It guards part of the seabed and repels intruders, sometimes chasing away fish several times its own size. The richer the site was in suitable algae for feeding, the more aggressive the fish became. Besides members of its own species, the main species chased away were parrotfish, bluehead wrasse ("Thalassoma bifasciatum"), bicolour damselfish ("Stegastes partitus") and ocean surgeonfish ("Acanthurus bahianus"). Certain other fish species, such as the smooth trunkfish ("Rhinesomus triqueter") and the graysby ("Cephalopholis cruentata"), were not chased away. The author of the study surmised it was the food source rather than the geographical area being guarded, and these fish were not considered to be threats because they did not graze algae, instead feeding on small invertebrates. An alternative possibility was these fish benefited the dusky damselfish in some other way, such as by providing some protection against predators or by removing invertebrates that feed on algae.