BIOL 2003 Lecture Notes - Lecture 14: Endostyle, Thaliacea, Larvacea
Chordates: Subphylums
October 28, 2015
Subphylums:
• Vertebrates
• Cephalochordates
• Urochordates
*Protochordates are a clade
Subphylum: Cephalochordata
• Amphioxus – pointy at both ends
• Branchiostoma (gill mouth) – lancelet *Proper genus name
• Cephalochordates: known as the poster chordates
o Burrow; seldom swim
o Marine filter feeders
o Around 30 species
• Body Plan:
o Huge filter feeding pharynx
▪ Cilia pump water
▪ Mucus from endostyle traps food
o Closed circulatory system with no heart
o Gill arch blood vessels
o Body surface is used for respiration (low metabolic rate)
o No head or brain *different from vertebrates
• Vertebrates?
o Display all chordate characteristics
o Segmented trunk musculature
o Similar blood circulatory system to vertebrates
o Fish-like body form
Subphylum: Urochordata
• =subphylum tunicate
• look completely different than other chordates
• Classes:
1. Ascidiacea (sea squirts) -most commonly seen
▪ Compound, colonial or solitary
▪ One of aquaculture’s worst enemies:
• Club, vase, golden star, and violet tunicates
• All common throughout Nova Scotia destroying fisheries
o Piling, mussel lines, scallop cage
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2. Appendicularia (ghost larvae)
3. Thaliacea (luxuriant; salps)
• TUNIC – only animal that makes cellulose like material used to surround their body tissue
• Filter feeders
• No cephalization or circulation
• Endostyle present secretes mucous
• Chordate??
o All 5 characteristics in larvae
o Only endostyle and pharynx remain in adults
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