BIOS
W2L2 Biodiversity II.pdf

Protostomes very diverse group arthropods crabs

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Protostomes Very diverse group: -- arthropods (crabs, barnacles, shrimp, centipedes, spiders, insects) -- molluscs (clams, oysters, octopuses, squid, snails, slugs, abalone) -- annelids (segmented worms, such as earthworms and leaches) 140 Need to know 141 Echinoderms -- Echinoderms (sea stars, sea urchins, sea cucumbers) ~7,500 species Calcified external plates create an external skeleton Water vascular system, including “tube feet” -- important for gas exchange, locomotion, and feeding 142
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Chordates Synapomorphies: - Dorsal hollow nerve chord - Tail that extends beyond the anus - Dorsal supporting rod called the “notochord” -In vertebrates, notochord becomes center of vertebrae (“nucleus pulposus”) during development - The lancelet is an early chordate Lancelet 143 Need to know Craniates Tetrapoda Sarcopterygii This tree is of the Craniates. Chordates (see previous tree) include lancelets (cephalochordata) & tunicates (Urochordata), both of which connect to the base of this tree 144 Great White Shark Ratfish Stingray Includes sharks, skates, rays, and ratfish (aka chimaera) >1000 species Skeleton made of cartilage (no bone!) Supportive structures in fins made out of keratin Chondrichyans 145
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Actinopterygii These are the “ray-finned fishes”, which have rays of bone in their fins ~32,000 species: Diverse! When you think of a “fish,” it is probably a ray-finned fish 146 Sarcopterygii These are the “lobe-limbed” vertebrates, in which the common ancestor had fleshy, lobed, paired fins that were joined to the body by a single bone (homologous to our humerus) This group includes Coelacanths, Lungfish, and Tetrapods This means that you are a human, a primate, a mammal, a tetrapod, and a sarcopterygiian fish! You are also a chordate, a deuterostome, and an animal… 147 Coelacanths Flourished in the Devonian until ~65 million years ago Long thought to be extinct, two species have been discovered 1938: Fishermen caught a coelacanth off the coast of South Africa 1998: New species caught off the Indonesian island of Sulawesi Important for understanding the evolution of the vertebrate limb 148
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  • Spring '18
  • MORRIS
  • Sarcopterygii

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