Introduction To Chordates 9. Chordata: Urochordata and Cephalochordata James Hake & Eden Berdugo.
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Transcript of Introduction To Chordates 9. Chordata: Urochordata and Cephalochordata James Hake & Eden Berdugo.
Introduction To Chordates
9. Chordata: Urochordata
and Cephalochordat
aJames 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
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)
James Hake & Eden Berdugo
•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
http://kentsimmons.uwinnipeg.ca/16cm05/16labman05/lb7pg1_files/34-02-ChordateCharacters-L.gif
Tunicates (subphylum Urochordata)
Sea Tulips
http://en.wikipedia.org/wiki/File:Sea-tulip.jpghttp://upload.wikimedia.org/wikipedia/commons/9/98/Bluebell_tunicates_Nick_Hobgood.jpg
Bluebell Tunicates
James Hake & Eden Berdugo
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
James Hake & Eden Berdugo
http://www.mun.ca/biology/scarr/142007_Urochordata.jpg
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
James Hake & Eden Berdugo
http://www.mun.ca/biology/scarr/142007_Urochordata.jpg
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.
James Hake & Eden Berdugo
http://www.mun.ca/biology/scarr/142007_Urochordata.jpg
Urochordata Review
http://www.mun.ca/biology/scarr/142007_Urochordata.jpg
James Hake & Eden Berdugo
Adult Tunicate Larvae Tunicate
Cephalochordata (Lancelets)
http://www.bethel.edu/~johgre/bio114d/LowerVerts.html http://www.mun.ca/biology/scarr/142007_Urochordata.jpg
James Hake & Eden Berdugo
Branchiostoma
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
James Hake & Eden Berdugo
http://www.mun.ca/biology/scarr/Cephalochordata.html
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
James Hake & Eden Berdugo
http://www.mun.ca/biology/scarr/Cephalochordata.html
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
James Hake & Eden Berdugo
http://www.mun.ca/biology/scarr/Cephalochordata.html
A Review of Cephalochordata (Lancelets)
http://www.bethel.edu/~johgre/bio114d/LowerVerts.html
James Hake & Eden Berdugo
Quiz1. Which is not a characteristic of all chordates?A. Notochord B. Radial Symmetry C. Nerve Cord D. Pharyngeal Slits
2. True or false: Urochordates are mobile throughout their entire lives.
James Hake & Eden Berdugo
3. Urochordates and cephalochordates feed by:A. ChemosynthesisB. PhotosynthesisC. Pharyngeal Slits and CleftsD. All of the Above
4. Regarding their notochords…A. Urochordates keep theirs for their entire lives, and
Cephalochordates do not.B. Cephalochordates keep theirs for their entire lives,
and Urochordates do not.C. Both Urochordates and Cephalochordates do NOT
keep theirs for their entire lives.D. Both Urochordates and Cephalochordates keep theirs
for their entire lives.
James Hake & Eden Berdugo
Answers1. B2. False3. C4. B
James Hake & Eden Berdugo