Elasmobranchii is the largest group of cartilaginous fish, containing Sharks (Selachii) and Rays (Batoidea).
Unlike bony fishes, cartilaginous fishes have a skeleton made of cartilage, which is light-weight, flexible and durable, and only about half the normal density of bone.
This lighter-weight skeleton allows cartilaginous fish to swim faster and use less energy than bony fishes.
Sharks and Rays have five to seven pairs of gill clefts which can open independently, rigid dorsal fins and small bony, pointed, tooth-shaped scales on the skin.
This sheath of tiny flat V-shaped scales covering the skin are called denticles. These scales are more like teeth than fish scales, helping sharks and rays to swim quickly through the water and providing protection from parasites.
Elasmobranch teeth are arranged in multiple rows and are replaced continually.
Members of this class don't have swim bladders, but instead their large livers are full of oil to provide buoyancy. The oil-filled liver can be up to 20% of the total animal weight.
All cartilaginous fishes employ internal fertilization and usually lay large, heavy-shelled eggs or give birth to live young.
Find Out More
- Allen, G., Steene, R., Humann, P., DeLoach, N. (2003) Reef Fish Identification, Tropical Pacific. Jacksonville, FL., USA: New World Publications, Inc., ISBN 1-878348-36-1.
- Humann, P., DeLoach, N., (2010) Reef Creature Identification, Tropical Pacific. Jacksonville, FL., USA: New World Publications Inc., ISBN 978-1-878348-44-9
- Debelius, H. (2013) Indian Ocean Reef Guide. Frankfurt, Germany: IKAN - Unterwasserarchiv, ISBN 978-3-939767-52-7.
- Debelius, H. (2004) Nudibranchs and Sea Snails, Indo-Pacific Field Guide. Frankfurt, Germany: IKAN - Unterwasserarchiv, ISBN 3-925919-51-1
- Erhardt, H., Knop, D. (2015) Corals Indo-Pacific Field Guide. Frankfurt, Germany: IKAN - Unterwasserarchiv, ISBN 3-925919-69-4.
- Veron J.E.N., Stafford-Smith M.G., Turak E. and DeVantier L.M. (2016). Corals of the World