Chondrichthyes

1. Chondrichthyes Hailey & Collin

2. Taxonomic Classification A. Kingdom - Animalia, Phylum - Chordata, Subphylum - Vertebrata, Infraphylum - Gnathostomata, Class - Chondrichthyes B. Carcharodon Carcharias (Great White)

3. Key Characteristics • They're cartilaginous fish, have a skeleton of cartilage. • Moveable jaws that typically have well developed teeth • Mouth is almost always ventral, or under the head • Paired lateral fins for efficient swimming • Rough, sandpaper like skin, due to tiny placoid scales • Include sharks, rays, skates, and chimaeras (also called ghost sharks)

4. Adaptations • First appeared roughly 395 million years ago • Sharks are can be referred to as "living fossils" • Caudal fin, or tail fin, is well developed and very powerful • Tail is usually heterocercal, meaning the upper lobe is longer than the lower lobe • Ancestors had bone, developed into cartilage

5. Habitat needs • Require salt water or, with some species, freshwater • A food source (fish, plankton, crustaceans, etc.) • Most rays require warmer temperatures • Most sharks require open waters

6. Reproduction • Fertilization is internal • Development is usually live birth • However, some species lay eggs (oviparous) • Some rare species are viviparous, meaning that the embryo develops inside the mother, eventually leading to live birth. • Some Chondrichthyes guard their eggs, but there is no care for the young after birth

7. Interesting facts • Most sharks have tongues, but not all of them can move them • Sharks do not have a swim bladder; instead they have a large liver filled with oil for buoyancy, with the exception of the Sandtiger Shark who swallows air to stay buoyant. • The Spiny Dogfish may incubate its young for as long as two years

10. Further Information: • http://en.wikipedia.org/wiki/Chondrichthyes • http://vertebrates.voices.wooster.edu/chondrichthyes/ • http://www.biodiversityexplorer.org/chondrichthyes/