1. Chordata

2. Phylum Chordata Subphylum Urochordata Subphylum Cephalochordata
Vertebrata
tunicates
lancets
Agnathans
Fish
Sharks
tetrapods

3. Characteristics of Chordates

4. Possible evolution of 1st fish
lancelet
Proto-vertebrate
Tunicate larvae
Adult tunicate

6. Early Chordate ancestor may have given rise to 1st vertebrate
Pikaia
Burgess Shale Fauna
Cambrian
mya

7. General Features Shared by Chordates:
Eukaryote
Multicellular
Bilateral- deuterstomes
Heterotrophic

8. Phylum Chordata Subphylum Urochordata - Tunicates
Class Ascidiacea - Sea Squirts
Solitary e.g. Styela montereyensis
Colonial - in groups but with own tunic
Compound Colonial - colonial with shared
tunic
Class Thaliacea - Salps (free swimming),
planktonic
Class Larvacea - Gelatinous house, planktonic

9. Subphylum Urochordata
tunicate

10. Subphylum Urochordata = tunicate
Tunicate - also called 'sea squirt'
notochord is confined to the tail
notochord is lost during metamorphosis into sessile adult
possess pharyngeal slits
Repro- sexual (hermaphroditic) & asexual (budding)

11. Tunicate Adult Anatomy

12. Tunicates: Free swimming larva:
notochord present only in free-swimming  larvum
notochord does not extend into head
larvum is free-swimming but non-feeding
adult is sessile filter feeder
Settled larva:
Settle after brief free-swimming larvum existence. 
Attaches at anterior end. 
Metamorphosis begins. 
Body turns 1800. 
Tail, notochord, dorsal nerve cord, disappear.

14. Class Larvacea - planktonic
Oikopleura

15. Class Larvacea - Gelatinous house, planktonic
Jelly-like house
Oikopleura
Marine snow

16. Class Thaliacea - Salps (free swimming), planktonic
Pyrosoma- bioluminescent
Colonial salp

17. Class Ascidiacea - Sea Squirts

18. Subphylum Cephalochordata
lancet
Strictly marine
Live buried in sand with head sticking out
Filter feeders

19. Lancet Anatomy