Biology · Ch 4 — Kingdom Animalia
Class Chondrichthyes
Class Chondrichthyes
Class Chondrichthyes (Greek chondron = cartilage, ichthyes = fish) includes animals such as Scoliodon (dog fish), Pristis (sawfish), electric ray, common skate, hammer-headed shark, Carcharodon (great white shark) and Trygon (sting ray).
These fishes have an entirely cartilaginous endoskeleton and are exclusively marine. The exoskeleton consists of placoid scales, and even the teeth are modified, backward-pointing placoid scales. The mouth is ventrally placed. Two pairs of lateral fins (pectoral and pelvic) are present, and the caudal fin is heterocercal — asymmetrical, with the upper lobe usually longer than the lower. …
What this figure shows. A labelled dogfish (Scoliodon) body showing the dorsal fin, lateral line, ventral mouth, gill clefts, pelvic fin, median ventral fin and asymmetrical caudal fin, alongside Anoxypristis (a sawfish relative) with its elongated toothed snout. …