RadiataSlides - 1 Next up: the RADIATA (Phyla Cnidaria...

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Unformatted text preview: 1 Next up: the RADIATA (Phyla Cnidaria & Ctenophora) Cnidaria : hydroids, jellyfish, sea anemones and corals Two phyla exhibit radial symmetry throughout life* *Both are considered the most primitive eumetazoans (multicellular animals with true tissues ) Ctenophora : comb jellies The major lineages of evolution in animals Fundamental evolutionary divergence among Eumetazoa (multicellular with true tissues) , but based on what? (symmetry) true tissues cellular only & Ctenophora Phylum Cnidaria “bearing stingers” ( cnidae ) over 9000 species mostly marine 2 [ FYI only : Cnidarians are an ancient group with the oldest fossil record (700 mya). There are about 4,500 fossil species primarily comprised of hard corals.] halosites favosites heliolites lithostrotion pachphyllum Palaeocyclus Calceola In Southeast Asia, jellyfish are eaten as a delicacy. cannonball jellyfish Cnidaria are a favorite food of sea turtles . Symmetry: radial Organization: tissue level with two germ layers; diploblastic There is no collective common name for cnidarians (jellyfish, corals, sea anemones, and hydroids are common names for the different classes). Cnidarians are either solitary or form colonies (below) : “brain” coral colony Portuguese man-of-war colony Gastrulation proceeds differently in animal embryos: Fig. 3.5 In the RADIATA, gastrulation ends here with only 2 germ layers (a diploblastic embryo with a “2-way”, “blind” or “incomplete” gut (only 1 opening) also called a gastrovascular cavity (GVC). 2 [ FYI only : Cnidarians are an ancient group with the oldest fossil record (700 mya). There are about 4,500 fossil species primarily comprised of hard corals.] halosites favosites heliolites lithostrotion pachphyllum Palaeocyclus Calceola In Southeast Asia, jellyfish are eaten as a delicacy. cannonball jellyfish Cnidaria are a favorite food of sea turtles . Symmetry: radial Organization: tissue level with two germ layers; diploblastic There is no collective common name for cnidarians (jellyfish, corals, sea anemones, and hydroids are common names for the different classes). Cnidarians are either solitary or form colonies (below) : “brain” coral colony Portuguese man-of-war colony Gastrulation proceeds differently in animal embryos: Fig. 3.5 In the RADIATA, gastrulation ends here with only 2 germ layers (a diploblastic embryo with a “2-way”, “blind” or “incomplete” gut (only 1 opening) also called a gastrovascular cavity (GVC). 3 new sessile (“attached”) sponge early free-swimming multicellular sponge embryo ( parenchymula larva) larva inverts, settles & develops into adult sponge (see also Fig. 6.10) Possible hypothesis: diploblastic embryo evolving from a sponge parenchymula larva?) Precursor to a gastrula?...
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This document was uploaded on 11/03/2011 for the course BSC2011L BSC2011L at FSU.

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RadiataSlides - 1 Next up: the RADIATA (Phyla Cnidaria...

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