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[1] (or Selachii) and are the sister group to the Batoidea (rays and kin).

2025年1月21日 · shark, any of numerous species of cartilaginous fishes of predatory habit that constitute the order Selachii (class Chondrichthyes). Sharks, together with rays and skates, make up the subclass Elasmobranchii of the Chondrichthyes.

Sharks can rouse fear and awe like no other creature in the sea. Find out about the world's biggest and fastest sharks, how sharks reproduce, and how some species are at risk of extinction.

Sharks are apex predators in the oceanic ecosystem with their diet consisting of mollusks, crustaceans, and fish. Mammals like porpoises, seals, sea lions, and dolphins, and large fish species including mackerel, tuna, and small sharks make up the diet of larger shark species.

2021年12月7日 · List of different types of sharks with pictures & facts. Discover amazing shark species, where found, lifestyle, conservation, classification.

Sharks and their relatives were the first vertebrate predators, and their prowess, honed over millions of years of evolution, allows them to hunt as top predators and keep ecosystems in balance. But sharks are in trouble around the world.

2024年11月19日 · Sharks, having evolved in Earth’s oceans more than 400 million years ago, have changed little since their emergence. Their streamlined bodies were built for speed and maneuverability in coral reef environments and the open ocean.

There are more than 1,000 species of sharks and rays, with new species discovered every year. These majestic top predators that are so essential to the natural order of marine ecosystems now face their most severe threat from overfishing. Many species are threatened with extinction, with some families of rays such as sawfishes in peril.

2019年12月13日 · There are several hundred species of sharks, ranging in size from less than eight inches to over 65 feet, and native to every marine environment around the world. These amazing animals have a fierce reputation and fascinating biology. A cartilaginous fish has a body structure formed of cartilage, instead of bone.

Sharks have different shapes, sizes, colors, fins, teeth, habitats, diets, personality, method of reproduction and other attributes. Some types of shark are very rare (like the Great White Shark and the Megamouth Shark) and some are quite common (like the Dogfish Shark and Bull Shark).