LIFESCI 1 Lecture Notes - Lecture 7: Opisthokont, Hox Gene, Cell Migration
Document Summary
1. 3 million described out of estimated 8-10 million extant species (based on dna sequences. Obtain necessary carbon compounds from other organisms. Most ingest their food rather than just absorbing it. Move under their own power at some ping in life cycle. Nerve cells and muscle cells (except in sponges) Cambrian explosion: radiation of animal phyla (~541 mya) Flagellated cells called choanocytes set up currents that draw water into the cavity. Gel -like mesohyl supports cells that form spicules and generate reproductive cells. Cells that line the exterior sense and respond to the external environment. Suspension filter feeds, spicules (sio2 or caco3) for support. Suspension filter feeding has evolved independently in several groups of animals includ bivalves, bandalles, and whales. Allow animals to sense and respond to their environment. Fundamental for complex behaviour and cognition in animals. All animals except for sponges used neurons to control behavior. Electrical impulse travels from one end to another (fast)
