What Are Chondrichthyes?

_{Chondrichthyes are a class of animals made up of cartilaginous fish that have skeletons primarily composed of cartilage. The fish classified in Chondrichthyes include, sharks, rays, skates, sawfish, and chimaeras.}

Chondrichthyes can be divided into two sub classes:

Elasmobranchii. Sharks, rays, and skates  are classified in Elasmobranchii. Members of the Elasmobranchii have no swim bladders, rigid dorsal fins, and their eyes have a tapetum lucidum.

Holocephali. Chimaeriformes is the only surviving order classified in the sub class holocephali.  Chimaeriformes is made up of  chimaeras, ghostsharks, rabbitfish, ratfish, and spookfish.

Physical Characteristics

All chondrichthyans breathe through five to seven pairs of gills, depending on the species. Chondrichthyans posses special “electroreceptors” known as Ampullae of Lorenzini that are a network of small mucus filled pores which help the fish sense electric fields in water. This helps them find prey, navigate, and sense the temperature.Some species have electric organs which can be used for defense and predation.

Range and Habitat

Chondrichthyans can be found in all the world’s oceans. 

Diet

The diet of Chondrichthyans includes;  jellyfish, dolphins, sea turtles, dugongs, seals, carrion, bony fish, octopus, cuttlefish, squid, other cartilaginous fishes, crustaceans, sea snakes, bivalves, and gastropods. 

Some Chondrichthyans have proven themselves to be opportunistic carnivores by eating horses, goats, sheep, dogs,  cats, rodents, and human beings. 

Definitions

1. Swim Bladder, A swim bladder is an internal gas filled organ that assists many bony fish with controlling their buoyancy; this also allows the fish to stay at their  current water depth without having to waste energy by swimming.
2. Tapetum Lucidum. A tapetum lucidum is  a layer of tissue in the eye of many animals that helps them see in very low light.

Fun Facts

1. Most sharks can see well in low light, have excellent night vision, and can see colors.
2. Jaws is a 1975 Movie directed by Steven Spielberg, based on the 1974 novel by Peter Benchley; the film is about a man-eating Great White Shark that has been attacking beachgoers.
3. The San Jose Sharks are a National Hockey League(N.H.L.) team.
4. Chimaeras are sometimes called ghost sharks.