26. Chordates Dec 2 2009

26. Chordates Dec 2 2009 - 1 Phylum Phylum Chordata...

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Unformatted text preview: 1 Phylum Phylum Chordata Chordata Urochodata Urochodata Cephalochordata Cephalochordata Vertebrata Vertebrata Bilateral Symmetry Deuterostomes Radial Cleavage Coelomate (coelom may be lost) Pharyngeal Gill Slits or Gill Pouches during some stage of the life history used for feeding in invertebrate taxa Dorsal Notochord present at some stage in development Dorsal elastic rod derived from mesoderm Lies below the nerve cord Dorsal, Hollow Nerve Cord present at some stage in development Pharyngeal Endostyle (Urochordata or Cephalochordata) or Thyroid (Vertebrata) (both concentrate iodine) Muscular, locomotor, Postanal Tail at some stage in development Tadpole stage some time in life history Gut complete, usually regionally specialized Circulatory system with a ventral contractile heart Dioecious or hermaphroditic schematic of general chordate characteristics 3 Subphyla Urochordata Urochordata Cephalochodata Cephalochodata Vertebrata Vertebrata Internal skeleton Brain case (skull) Vertebral column (backbone) Invertebrates 2 Urochordata ~3000 Species sea squirts, tunicates, salps, larvaceans All marine no coelom body cavity ~ hemocoel Tunic made of Tunicin = cellular has Cellulose, other compds. blood spaces, amoebocytes, etc. outside epidermis, but not just an outer covering Ascidacea- tunicates, sea squirts Thaliacea- salps Larvacea- larvaceans Class Ascidiacea ~1500 described species Adults sessile Non Feeding Larva - Tadpole Body two parts: Trunk , Tail Tail - Notochord Trunk Visceral Ganglion (dorsal) Sensory Vescicle w/ eye spot Statocyte statocyst cell Larvae cannot feed - short larval stage Need to metamorphose to feed Large , non-feeding Short lived Attach to hard substrata Metamorphosis, resorb tail Non-feeding contrary to drawing siphons in larva do not open outside Adult Oral Siphon (incurrent) Pharyngeal Basket cilia move water (2-3 L / hr) mucus traps food Atrial Siphon Oral Siphon...
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26. Chordates Dec 2 2009 - 1 Phylum Phylum Chordata...

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