can you please describe the second one to me
They are characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head.
Shark
characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head.
please tell me more about jaekelopterus It is a genus of predatory eurypterid, a group of extinct aquatic arthropods. is their species still alive? UNANSWERABLE where can they be found? It lived in non-marine aquatic environments. you mentioned that these were predators, what more can you tell me about them as predators? Fully grown "Jaekelopterus" would have been apex predators in their environments and likely preyed upon smaller arthropods (including resorting to cannibalism) and early vertebrates. you mean they ate each other, but what would be the benefit? UNANSWERABLE what harm can come by eating each other? It has been shown in some studies that the risk of encountering an infected victim increases when there is a higher cannibalism rate. do you know any other species that eats each other? Aquatic ecosystems please tell me more about this Communities of organisms that are dependent on each other and on their environment live in aquatic ecosystems. can you please name a few of these organisms Whales, sharks, and tuna live etc can you please describe the first one to me UNANSWERABLE
wiki:11630856
Shark [SEP] Introduction
Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimorpha (or Selachii) and are the sister group to the rays. However, the term "shark" has also been used for extinct members of the subclass Elasmobranchii outside the Selachimorpha, such as "Cladoselache" and "Xenacanthus", as well as other Chondrichthyes such as the holocephalid eugenedontidans. Under this broader definition, the earliest known sharks date back to more than 420 million years ago.