Shark is not a fish
Shark Quotes (28 quotes)
Why Don't Sharks Have Bones?
These are common misunderstandings about sharks. No, a shark is not a mammal like whales, nor is it a reptile like alligators. A shark is actually a fish! Sharks are cartilaginous fish , meaning that their skeletons are made entirely of cartilage the same squishy material that is found in our human nose and ears. Perfectly named, a Whale Shark can grow to be as large as a school bus! They can grow 10 inches a year until they reach 12 to 14 feet.
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 million years ago. Since then, sharks have diversified into over species. They range in size from the small dwarf lanternshark Etmopterus perryi , a deep sea species of only 17 centimetres 6. They generally do not live in freshwater although there are a few known exceptions, such as the bull shark and the river shark , which can be found in both seawater and freshwater.