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Introduction To Chordates

Introduction To Chordates. 9. Chordata: Urochordata and Cephalochordata. James Hake & Eden Berdugo. What is a chordate?. Vertebrates are a subphylum of the phylum Chordata (the chordates) Chordates are bilateral Belong to a clade of animals known as Deuterostomia. James Hake & Eden Berdugo.

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Introduction To Chordates

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  1. Introduction To Chordates 9. Chordata: Urochordata and Cephalochordata James Hake & Eden Berdugo

  2. What is a chordate? • Vertebrates are a subphylum of the phylum Chordata (the chordates) • Chordates are bilateral • Belong to a clade of animals known as Deuterostomia James Hake & Eden Berdugo

  3. Derived Characteristics of Chordates • Notochord • a longitudinal, flexible rod; provides flexible skeletal support • Dorsal Hollow Nerve Chord • develops into central nervous system (brain/spinal cord) http://kentsimmons.uwinnipeg.ca/16cm05/16labman05/lb7pg1_files/34-02-ChordateCharacters-L.gif • Pharyngeal Slits or Clefts • grooves that develop into slits that open to the outside of the body; used in gas exchange and feeding • Muscular, Post-Anal Tail • A tail extending posterior to the anus that contains skeletal elements and muscles; propelling force in aquatic species James Hake & Eden Berdugo

  4. James Hake & Eden Berdugo Tunicates (subphylum Urochordata) Sea Tulips Bluebell Tunicates http://upload.wikimedia.org/wikipedia/commons/9/98/Bluebell_tunicates_Nick_Hobgood.jpg http://en.wikipedia.org/wiki/File:Sea-tulip.jpg

  5. Categories • Body Cavity • Coelemate • Body cavity lost in adults • Body symmetry • Bilateral • Nervous System • Simple brains with ganglion clusters • Circulatory System • Closed circulatory system in which blood is transported • Blood circulation powered by heart http://www.mun.ca/biology/scarr/142007_Urochordata.jpg James Hake & Eden Berdugo

  6. Categories [Continued] • Digestive System: • Suspension feeders; feed by filtering sea water through pharyngeal slits, where food gets caught in a mucus lining • Two openings in body cavity: in-current and ex-current siphon • Excretory System • None • Locomotion/Musculature • Sperm are mobile, but adults are immobile • Skeletal Type • None • Invertebrate http://www.mun.ca/biology/scarr/142007_Urochordata.jpg James Hake & Eden Berdugo

  7. Categories [Continued] • Sensory Structures • Light/gravity sensing cells in the larvae • Reproduction • Hermaphrodites (ie asexual reproduction) • Gas Exchange • Absorb through pharynx • Unique Features • As larvae, they move around until they find a suitable environment to become permanently fixed to. http://www.mun.ca/biology/scarr/142007_Urochordata.jpg James Hake & Eden Berdugo

  8. Urochordata Review Adult Tunicate Larvae Tunicate http://www.mun.ca/biology/scarr/142007_Urochordata.jpg James Hake & Eden Berdugo

  9. Cephalochordata (Lancelets) Branchiostoma http://www.mun.ca/biology/scarr/142007_Urochordata.jpg http://www.bethel.edu/~johgre/bio114d/LowerVerts.html James Hake & Eden Berdugo

  10. Categories • Body Cavity • Coelomate • Body Symmetry • Bilateral Symmetry • Nervous System • Dorsal, hollow nerve cord • Hox genes control development of brain • No full-fledged brain; only have swollen tip on the anterior end of the nerve cord • Circulatory System • Contains heart • Closed Blood System http://www.mun.ca/biology/scarr/Cephalochordata.html James Hake & Eden Berdugo

  11. Categories [Continued] • Digestive System • Use pharyngeal slits lined with mucous to remove tiny food particles • Excretory System • Composed of paired nephridia (a tubule open to the exterior; has ciliated or flagellated cells and absorptive walls) • Locomotion/Musculature • Simple swimming mechanism • Coordinated contractions of muscles in chevrons (<<<) produce movement • Muscle segments called somites • Skeletal Type • No solid skeleton, but has flexible notochord • Invertebrate http://www.mun.ca/biology/scarr/Cephalochordata.html James Hake & Eden Berdugo

  12. Categories [Continued] • Sensory Structures • Poorly developed • Reproduction • Separate Sexes • Males and females have multiple paired gonads • External Fertilization • Gas Exchange • Pharynx and pharyngeal slits aid gas exchange, which occurs across the external body surface • Other Unique Features • Lancelets’ bodies aren’t hard, so little fossil evidence • Adult lancelets live in the sand with their anterior ends exposed to remove tiny food particles http://www.mun.ca/biology/scarr/Cephalochordata.html James Hake & Eden Berdugo

  13. A Review of Cephalochordata (Lancelets) http://www.bethel.edu/~johgre/bio114d/LowerVerts.html James Hake & Eden Berdugo

  14. Quiz • Which is not a characteristic of all chordates? • Notochord • Radial Symmetry • Nerve Cord • Pharyngeal Slits 2. True or false: Urochordates are mobile throughout their entire lives. James Hake & Eden Berdugo

  15. 3. Urochordates and cephalochordates feed by: • Chemosynthesis • Photosynthesis • Pharyngeal Slits and Clefts • All of the Above 4. Regarding their notochords… • Urochordates keep theirs for their entire lives, and Cephalochordates do not. • Cephalochordates keep theirs for their entire lives, and Urochordates do not. • Both Urochordates and Cephalochordates do NOT keep theirs for their entire lives. • Both Urochordates and Cephalochordates keep theirs for their entire lives. James Hake & Eden Berdugo

  16. Answers • B • False • C • B James Hake & Eden Berdugo

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