text: sand tiger the smalltooth sand tiger or ragged - tooth ( odontaspis ferox ) is a species of mackerel shark in the family odontaspididae , with a patchy but worldwide distribution in tropical and warm temperate waters . they usually inhabit deepwater rocky habitats , though they are occasionally encountered in shallow water , and have been known to return to the same location year after year . this rare species is often mistaken for the much more common grey nurse shark ( carcharias taurus ) , from which it can be distinguished by its first dorsal fin , which is larger than the second and placed further forward . it grows to at least 4 . 1 m ( 13 . 5 ft ) in length . very little is known of the biology and behavior of the smalltooth sand tiger . it is an active predator of benthic bony fishes , invertebrates , and cartilaginous fishes . this species is thought to be ovoviviparous with oophagous embryos like other mackerel sharks . in contrast to its formidable size and appearance , this shark is harmless , having never been known to behave aggressively towards humans . there is concern that its numbers are declining due to human activities in the mediterranean and elsewhere , though existing data is inadequate for a full assessment of its conservation status . taxonomy and phylogeny the smalltooth sand tiger was originally described as squalus ferox by italian - french naturalist antoine risso in 1810 , based on a specimen from nice , france . in 1950 , gilbert percy whitley described o. from australian specimens , separating them from o. ferox on the basis of dentition and the absence of spots . leonard compagno synonymized the two species in 1984 , as subsequently discovered pacific specimens had blurred whitley 's distinguishing characters . the specific epithet ferox is latin for " fierce " . other common names for this shark include blue nurse shark , fierce shark , herbst 's nurse shark , and sand tiger shark . a phylogenetic study based on mitochondrial dna , performed by naylor et al. in 1997 , suggests that the smalltooth sand tiger and its relative , the bigeye sand tiger ( o. noronhai ) , are more closely related to the thresher sharks than to the grey nurse shark , to which it bears a strong resemblance . if true , this would indicate that the similarities between this species and the grey nurse shark arose as the result of convergent evolution . fossil teeth belonging to the smalltooth sand tiger have been found from lower pliocene ( 5 . 3 – 3 . 6 ma ) deposits in italy and venezuela . description the smalltooth sand tiger has a bulky body with a long , bulbous , slightly flattened snout . the eyes are medium - sized , with large round pupils ( as opposed to slit - like in the grey nurse shark ) , and lack nictitating membranes . the mouth is large and filled with projecting teeth . each tooth has a narrow , tall central cusp flanked by 2 - 3 pairs of lateral cusplets . there are 48 – 56 tooth rows in the upper jaw and 36 – 46 tooth rows in the lower jaw ; the front large teeth in the upper jaw are separated from the lateral teeth by 2 – 5 intermediate teeth . the fins are broad - based and angular in shape . the first dorsal fin is larger than the second and placed closer to the pectoral fins than the pelvic fins . the caudal fin is strongly asymmetrical with the upper lobe much longer than the lower . the coloration is gray to gray - brown above and lighter below . juveniles are uniform in color with darker fin margins , while adults often exhibit dark spots or blotches that vary widely in pattern , size , and density . coloration also appears to vary by region , with some individuals from the mediterranean displaying a patchy , " piebald " pattern . the smalltooth sand tiger attains a maximum length of 4 . 1 m ( 13 . 5 ft ) and a maximum weight of 289 kg ( 637 lbs ) . there are unconfirmed reports of much larger individuals from island off colombia . distribution and habitat sand tigers have been caught at widely scattered locations throughout the world , indicating a possibly circumtropical distribution . in the eastern atlantic ocean , it is known from the bay of biscay south to morocco , including the mediterranean sea , the azores , and the canary islands . in the western atlantic , it has been reported from off north carolina and florida ( usa ) , the yucatan peninsula ( mexico ) , and fernando de noronha ( brazil ) . it occurs throughout the indian ocean , from south africa , madagascar , and tanzania in the west to the maldives and the southwest indian ridge in the east . in the northern pacific it is known from off japan , hawaii , california , and colombia , and in the southern pacific it is known from new caledonia , eastern australia , and new zealand . typically regarded as a deepwater species , the smalltooth sand tiger has been caught down to a depth of 880 m ( 2 , 900 ft ) . they are usually found near the bottom in rocky , boulder - strewn regions on continental shelves and the upper continental slope , as well as around submarine ridges and mountains . there are also reports of this species near the drop - offs of rocky or coral reefs and in the upper layers of the open ocean . in the mediterranean , smalltooth sand tigers occur at depths less than 250 m ( 820 ft ) , including at depths accessible to divers . they have been seen swimming over sandy flats at cocos island and fernando de noronha . the temperature range favored by this species is 6 – 20 ° c ( 43 – 63 ° f ) ; in hot climates they are found below the thermocline in cooler water . biology and ecology the smalltooth sand tiger is a strong - swimming shark that may be encountered singly or in aggregations of up to five individuals . catch records suggest that this species may cover long distances in oceanic waters along underwater ridges or " hopping " between seamounts . it has a very large , oily liver , which allows it to maintain neutral buoyancy in the water column with minimal effort . at a location called " shark point " off beirut , lebanon , small groups of smalltooth sand tigers appear every summer on rocky reefs at a depth of 30 – 45 m ( 100 – 150 ft ) . the same individuals have been documented returning to this site year after year . their purpose there is unknown , being speculated to relate to mating . when confronted , these sharks have been observed to stall , gape their mouths , turn around , and shake their tails towards the perceived threat . adult smalltooth sand tigers have no known predators , though they are bitten by cookiecutter sharks ( isistius brasiliensis ) . a known parasite is the tapeworm gracile , which infests the shark 's spiral valve intestine . the carcass of a 3 . 7 m ( 12 . 1 ft ) long female found off fuerteventura in the canary islands contained a number of snubnosed eels ( parasitica ) inside her heart , body cavity , and back muscles . it is unknown whether the eels contributed to the shark 's death . feeding compared to the grey nurse shark , the dentition of the smalltooth sand tiger is less robust and lacks specialized cutting and crushing teeth , suggesting that it tends to tackle smaller prey . the diet of the smalltooth sand tiger consists of bottom - dwelling bony fishes such as rockfish ( sebastes spp . ) , invertebrates such as squid , shrimp , and possibly marine isopods , and cartilaginous fishes including rays and chimaeras . the largest known prey item taken by this species was a 1 . 3 m ( 4 . 3 ft ) long kitefin shark ( dalatias licha ) , found inside the stomach of a 2 . 9 m ( 9 . 5 ft ) long male from new caledonia . life history no pregnant smalltooth sand tigers have ever been found ; this species is presumed to be ovoviviparous as in other mackerel sharks . - ( 1996 ) described a 3 . 6 m ( 11 . 8 ft ) female from the gulf of california that contained " hundreds of ova " in her right ovary , which would support the embryos being oophagous . whether the embryos also cannibalize each other as in the grey nurse shark is unknown . the size at birth is estimated to be 1 . 0 – 1 . 1 m ( 3 . 3 – 3 . 6 ft ) . with a few recorded exceptions , juveniles are found in deep water and only adults are present above a depth of 200 m ( 660 ft ) ; this may serve to reduce predation on young individuals by large , shallow - water predators such as the great white shark ( carcharodon carcharias ) . males mature at a length of 2 . 0 – 2 . 5 m ( 6 . 6 – 8 . 2 ft ) and females at a length of 3 . 0 – 3 . 5 m ( 9 . 4 – 11 . 5 ft ) . faint scars seen on some individuals may be related to courtship . human interactions encounters with divers have shown that , despite their size , smalltooth sand tigers are docile and do not react aggressively even when closely approached . this species is taken as bycatch in gillnets , bottom trawls , and on longlines ; most captures occur in the mediterranean and off japan . it is usually discarded when caught , except in japan where the meat is consumed ( though considered very inferior to the grey nurse shark ) and the liver oil is utilized . the fins , jaws , and cartilage are also of value . discoveries , beginning in the 1970s , of smalltooth sand tigers in shallow water have raised urgent conservation concerns , as this species is apparently more vulnerable to human activity than previously believed . there is at present insufficient data for the international union for conservation of nature ( iucn ) to assess the worldwide conservation status of this species . it has been assessed as vulnerable in australian waters , due to a decline of over 50 % in catches off new south wales since the 1970s . populations of this species in the mediterranean are also believed to have declined , due to a combination of habitat degradation , overfishing , pollution , and human disturbance . the smalltooth sand tiger has been protected by the australian government since 1984 ; this came about concurrently with protection for the grey nurse shark , which had been decimated in australian waters , so as to prevent any claims of confusing one species for the other . however , these regulations have proven difficult to enforce .