The features of chordates, the subphyla, and the classes of vertebrates: jawless fishes, cartilaginous and bony fishes, amphibians, reptiles, birds and mammals.
3 lessons, about 1 h 35 min3 simulations10 problems4 practice questionsPython in every lesson
Created by StemPy LabA chordate has a notochord, a dorsal hollow nerve cord, gill slits in the pharynx and a post-anal tail, at least in the embryo. The phylum has three subphyla. Urochordates keep the notochord only in the larval tail, cephalochordates keep it for life, and vertebrates replace it with a vertebral column.
Cyclostomes are jawless and suck on fishes. Cartilaginous fishes, the sharks and rays, have separate gill slits, placoid scales and no air bladder. Bony fishes have an operculum over four pairs of gills and an air bladder. Amphibians live on land and in water, with moist skin, a cloaca and a three-chambered heart.
Reptiles have dry skin with scales, usually a three-chambered heart, internal fertilisation and shelled eggs. Birds have feathers, a beak, hollow bones, air sacs and a four-chambered heart, and they keep a steady temperature. Mammals have hair, mammary glands, external ears and a four-chambered heart, and most give birth to live young.
Log in to join the discussion.
Loading…