BIO 121 Lecture Notes - Lecture 22: Gastrovascular Cavity, Rotifer, Flatworm
27 Nov 2017
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Document Summary
Ca of all animals was similar to modern choanoflagellates. Sponges (porifera) are basal animals that lack tissues. The basic body plan of cnidarian is a sac w/ tentacles; a single opening acts as both the mouth and anus. Gastrovascular cavity: central digestive compartment derived from endoderm. Cnidarians are carnivores that use tentacles to catch prey. The tentacles are armed w/ cnidocytes, unique cells that function in defense and capture of prey. Nematocysts are specialized organelles w/i cnidocytes that eject a stinging thread. Coral reefs are crucial ecosystems that provide habitats for many species. Reef-building corals need calcium carbonate to build shells, but excess co2 leads to acidic oceans which deplete carbonate. Most have a true coelom and a digestive tract w/ two openings. Ecdysozoans have a cuticle, and they molt. Can maximize their surface area by being flat. Trematodes are an ex of parasitic platyhelminthes. Live in freshwater, marine and damp soil. Some are asexual and lack males entirely.
