Chondrichthyes

Chondrichthyes is the class of jawed vertebrates whose skeletons are primarily cartilage rather than bone. Its living members include sharks, rays, skates, and chimaeras.

Vertebrate: An animal with a backbone or an embryonic structure that develops into one. Chondrichthyans are vertebrates whose skeletons remain primarily cartilaginous.
Sharks: A diverse group of cartilaginous fishes, typically with gill slits along the sides of the head. Sharks are one of the best-known living branches of Chondrichthyes.
Internal fertilization: Fertilization in which sperm enters the female reproductive tract before an egg is fertilized. Male chondrichthyans use claspers to transfer sperm during mating.
Early Devonian: The first age of the Devonian Period, spanning approximately 419 to 393 million years ago. Fossils assigned to early chondrichthyan relatives appear in Devonian deposits.
Shark finning: The practice of removing a shark’s fins, often while discarding the rest of its body at sea. Finning contributes to fishing pressure on sharks and other chondrichthyans.
Gnathostomata: The clade of vertebrates with jaws, including cartilaginous fishes and bony vertebrates. Jaws place Chondrichthyes within this larger vertebrate group.
Rays: Cartilaginous fishes with flattened bodies and enlarged pectoral fins joined to the head. Rays illustrate a body plan adapted to life close to the seafloor.
Oviparity: A reproductive mode in which embryos develop in eggs laid outside the parent’s body. Some chondrichthyans lay egg cases that protect developing embryos.
Cladoselache: An extinct shark-like fish known from Late Devonian fossils in Ohio. Its fossils preserve an early example of a shark-like chondrichthyan body plan.
Bycatch: The unintended capture of animals during fishing directed at other species. Chondrichthyans are frequently caught unintentionally in fisheries targeting other animals.

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