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Phylum Invertebrate Chordates

Lancelets, Tunicates & Sea Squirts . Phylum Invertebrate Chordates . Lancelets, Tunicates & Sea Squirts. Key Characteristics. Deuterostome – possessing a notochord Includes the subphyla Vertebrata Mammals Fishes Amphibians Reptiles B irds Tunicata – salps , sea squirts

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Phylum Invertebrate Chordates

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  1. Lancelets, Tunicates & Sea Squirts Phylum Invertebrate Chordates Lancelets, Tunicates & Sea Squirts

  2. Key Characteristics • Deuterostome – possessing a notochord • Includes the subphyla Vertebrata • Mammals • Fishes • Amphibians • Reptiles • Birds • Tunicata – salps, sea squirts • Cephalochordata – lancelets • Tunicates and lancelets do not have any back bone

  3. Anatomy • Oral Siphon • Atrial Siphon • Notochord – flexible rod of tissue • Dorsal nerve chord • Pharyngeal slits

  4. Digestion • Suspension feeders • Filtering through siphon • Incurrent – takes in water and food • Excurrent – expels wastes • Pharyngeal slits • Action of cilia passes food • Esophagus and anus opening

  5. Respiration • No respiratory system • Lancelets breathe through their skin • Their skin consists of a simple epithelium • Little respiration occur in the gill slits • They have no blood cells like regular fish

  6. Internal Transport • Digestive tube running from mouth to anus • Communal vascular system • Pharyngeal slits – serve as feeding structures • Can serve as respiratory structures • Takes place along external body surfaces

  7. Response • Elaborate systems that allow them to respond to stimuli in their environment • Relatively simple nervous system • Do not have specialized sensory organs • Lancelets have a hollow brain and small eyespots that detect light • Sensory cells in tunicates may help control water passing through the pharynx

  8. Movement • Rod-like structure in tail called notochord • A part of the tails musculature • Allows the Tunicate Larvae to swim more efficiently • Only the Larvae retain the tadpole shape of the tail • Notochord is only found in the Larvae

  9. Reproduction • Sexual reproduction • Two sexes in each species • Sperm and egg are released into the water • Fertilization occurs • Can reproduce asexually

  10. Examples Lancelet Tunicate Sea Squirt

  11. Facts • There are 60,000 living species of chordates • There are about 30 lancelet species • Around 896 – 900 million years old • Lancelets can grow up to about 2.8” long • Sea Squirts can get up to 3.9” in size

  12. Literature Cited • http://en.wikipedia.org/wiki/Chordate • http://www.cliffsnotes.com/study_guide/Chordata.topicArticleId-8741,articleId-8694.html • http://en.wikipedia.org/wiki/Lancelet • Biology Book • http://www.mcwdn.org/Animals/Chordate.html

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