Chordate Characteristics
- Presence of notochord (internal supporting rod) at some stage in life
- Pharyngeal gill slits
- Post-anal tail
- Segmented muscles
- Dorsal hollow nerve cord
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Subphylum Urochordata — Tunicates
Characteristics
- Notochord, dorsal nerve cord, and tail only present in larval stage
- Adults usually soft-bodied sac-like, sessile filter feeders
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Spiny Sea Squirt, Halocynthia sp.
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Tunicate, possibly Pyura sp.
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Pacific Star Tunicate, Botryllus sp.; a colonial form: each small orange spot is a single individual; La Jolla, CA.
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Social Tunicate, Metandrocarpa taylori; La Jolla, CA.
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Mangrove Tunicate, Ecteinascidia sp., stained whole mount.
See also labeled photo.
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Ascidian "Tadpole" Larva, stained whole mount
See also labeled photo.
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Subphylum Cephalochordata — Lancelets
Characteristics
- Elongate, laterally flattened, fish-like animals
- Tail and notochord persist throughout life
- Presence of tail (caudal) fin
- Notochord extends anteriorly past nerve cord
- Muscles segmented into myomeres
- Burrow in marine sediments
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Lancelet (aka Amphioxus), Branchiostoma lanceolatum, stained whole mount
See also labeled photo.
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Lancelet (aka Amphioxus), Branchiostoma lanceolatum, stained cross section from mid-pharynx
See also labeled photo.
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Subphylum Vertebrata — Vertebrates
Characteristics
- Brain enclosed in cartilagenous or bony cranium
- Fewer pharyngeal gill slits (used for respiration instead of feeding)
- Notorcord supplemented by or replaced with segmented vertebrae in most
- Larger, more complex brain and sense organs
- More complex visceral organs
- Includes fishes (jawless, cartilagenous, and bony), amphibians, reptiles, birds, and mammals
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Vertebrates are not covered in this class.
To learn more about this subphylum, consider enrolling in LSC 370.
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