Biology 3229F/G Lecture Notes - Lecture 1: Body Plan, Cambrian Explosion, Cnidocyte
24 Feb 2019
School
Department
Course
Professor
Document Summary
Unicellular life occurred about 2 billion years ago (pre-cambrian period) 542 million years ago = cambrian explosion (origin of life: wide range of organisms that represent a life form that we have today, explosion = adaptive radiation within animal life, metazoan life = multicellular life. Around 107 million animals discovered, estimated 1. 8 million animals. 34-36 phyla for animals; not a single phylum has an origin in a terrestrial environment: bauplan = set of morphological features common to members of a phylum. Subphylum anthozoa: subclass hexacorallia, subclass octocorallia. Subphylum medusozoa: class scyphozoa, class cubozoa, class hydrozoa. Jellyfish are pelagic, very simple bauplan, occur in blooms, form colonies: atoll: whole reef is composed of corals (cnidarians) High speed film (40,000 frames/s) of nematocyst discharge. Using hydrostatic pressure, releases a harpoon which can penetrate skin. Medusa stage is absent but they have a planula. Anthozoan, order scleractinia (true corals: groove brain coral, staghorn coral) Majority are colonial (polyps are connected via their guts)
