BIOL 121 Lecture Notes - Lecture 25: Endoskeleton, Symmetry In Biology, Cephalization

• School: U of S
• Department: Biology
• Course: BIOL 121
• Professor: Jeff Sereda& Mike Pollock

Document Summary

2 groups of chordates invertebrate and vertebrate. Streamlined body more easily passes through water. Mucous secreted on surface of skin and scales to reduce drag through water and resist parasites. Advanced cephalisation many senses eyes, ears, nostrils (2 sets), lateral line. Lateral line system modified scales allow water to be directed over sensory cells at base detects motions from other fish, water currents. Fins 4 unpaired, 2 sets of paired fins - pectoral and pelvic. Modified gill arches for respiration (gill rakers protect filaments) Motile muscle attaches to skeleton, main propulsion from axial motion. Sexual gametic life cycle, separate sexes, external fertilization and egg development.