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)
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. Tunicates (subphylum Urochordata)
James Hake & Eden Berdugo
Tunicates (subphylum Urochordata)
Sea Tulips
Bluebell Tunicates

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
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
Invertebrate
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.
James Hake & Eden Berdugo

8. Urochordata Review Adult Tunicate Larvae Tunicate
James Hake & Eden Berdugo

9. Cephalochordata (Lancelets)
Branchiostoma
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
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
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
James Hake & Eden Berdugo

13. A Review of Cephalochordata (Lancelets)
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
James Hake & Eden Berdugo