FISH 311 Lecture Notes - Lecture 19: Lake Malawi, Cambrian Explosion, Sarcopterygii
23 Feb 2018
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Document Summary
No legs in snakes, caecilians and legless lizards. Morphology of cichlids in lake malawi and lake t. Post-anal tail (for some sort of life cycle) Sessile adults with free swimming larvae (no movement adults) Synapomorphy = notochord extends to front end of body. Gills thought evolve from the ectoderm (vs. endoderm: gills evolved independently!) But gills evolve only once (endoderm origin), are actually a synapomorphy cyclostomes + gnathostomes. Each individual has both reproductive tissues, although only one is active. Cash prize for reproductive information on myxine (1854, unclaimed) Hagfish spawn multiple times throughout their life span. Tend to be fewer in number (per spawning event) Are the predominant type of egg found in freshwater fishes. Adults live ~ 2 years and migrate to spawn. Not true parasites - hosts usually die (really just predators) All anadromous lampreys are parasitic but not all. All anadromous lampreys are parasitic but not all freshwater lampreys are parasitic
