They are marine animals with streamlined body and have cartilaginous endoskeleton. Mouth is located ventrally. Notochord is persistent throughout life. Gill slits are separate and without operculum (gill cover). The skin is tough, containing minute placoid scales. Teeth are modified placoid scales which are backwardly directed. Their jaws are very powerful. These animals are predaceous. Due to the absence of air bladder, they have to swim constantly to avoid sinking (Watch Class Chondrichthyes Video to learn more).
Heart is two-chambered (one auricle and one ventricle). Some of them have electric organs (e.g., Torpedo) and some possess poison sting (e.g., Trygon). They are cold-blooded (poikilothermous) animals, i.e., they lack the capacity to regulate their body temperature. Sexes are separate. In males pelvic fins bear claspers. They have internal fertilisation and many of them are viviparous. They are marine fishes with cartilaginous endoskeleton. The exoskeleton has placoid scales. E.g. Scoliodon
Examples: Scoliodon (Dog fish), Pristis (Saw fish), Carcharodon (Great white shark), Trygon (Sting ray).
The Cartilaginous Fishes (Class Chondrichthyes) include sharks, skates, and rays.
1) They are cold-blooded vertebrates.
2) Their skeleton is made of cartilage instead of bone. Cartilage is softer than bone (it makes up your outer ear or the end of your nose).
3) They breathe through gills.
4) Their teeth are very hard and when they lose them, biting into tough prey, they can replace them within days. Many chondrichthyes, including sharks, make new teeth as needed their whole lives.
5) They have 2 pairs of fins, one pair in the front (pectoral fins) and one pair in back. Sharks are famous for their large dorsal fin seen above the water as they swim along the surface. Chondrichthyes have remained almost unchanged since the time of the dinosaurs.
Class Chondrichthyes Video
Useful for CBSE, ICSE, NCERT & International Students
Grade : 9
Subject : Biology
Lesson : Diversity in The Living World
Topic: Class Chondrichthyes Video
Visit www.oztern.com to find personalized test preparation solutions for Pre Medical – AIPMT, AIIMS, JIPMER, State, Pre Engineering – IIT JEE, JEE MAIN, BITSAT, State and Foundations – Class 6 to 10.