BIOL 1108 Lecture Notes - Lecture 17: Axial Skeleton, Matrotrophy, Deuterostome
Document Summary
Hemichordates are marine deposit feeders and filter feeders and are the sister group to the echinoderms. Echinoderms (phylum echinodermata) are unsegmented deuterostomes with radial symmetry and an endoskeleton. Chordates (p. chordata) are bilaterally symmetric, segmented deuterostomes with a notochord and pharyngeal slits. The tunicates, the lancelets, and the hagfish are chordates without backbones. The vertebrates (vertebrata) have a jointed axial skeleton. The chondrichthyes and the osteichthyes are gnathostomes with jaws, paired fins, and calcified skeletons. Endothermy and matrotrophy evolved repeatedly in the vertebrates. The amphibia are tetrapods that remain dependent on free water for reproduction. Amniotes are tetrapods that retain internal water in the egg. The mammalia are amniotes with hair and glands. The reptilia are amniotes with scales of keratin. Bilaterians, including protostomes and deuterostomes, have bilateral symmetry and develop from three germ layers. All of the remaining animals belong to this group. Synapomorphies: features of larval development and dna.
