Cartilaginous Fish | Chondrichthyes
Chondrichthyes refers to a class of fish or vertebrates that feature paired fins and an internal skeleton composed of cartilage. Noticeable characteristics of cartilaginous fish include the capability of numerous species to breathe through gills and spiracles, skin dressed in dermal denticles to give protection, a small brain with several sensory organs, and an adaptive immune system. Additionally, these fish lack swim bladders, are often predatory, and show jaws and paired appendages. They are likewise an excellent source of food for humans. Chondrichthyes are further divided into Elasmobranchii and Holocephali and can be found both in freshwater and marine environments.
Cartilaginous fish are different from bony fish through their skeletons that are made of mostly cartilage as opposed to bony fish which have skeletons composed mostly of bone. Both cartilaginous and bony fish fall under different types of taxonomic groups. Cartilaginous fish are part of the Chondrichthyes while bony fish are of the Osteichthyes class.
Cartilaginous fish maintain their buoyancy through their liver which is filled with oil. The oil within their liver helps cartilaginous fish lighten their body to keep it from sinking downwards into the body of water, while also helping the fish save energy to keep moving and direct themselves.
Cartilaginous fish have movable jaws that are equipped with fully developed teeth. The mouth of cartilaginous fish is typically located under their head. Cartilaginous fish only have one set of oral jaws that are made of cartilage. The jaws of cartilaginous fish are articulated and opposed vertically.