Phylum Hemichordata Subphylum Urochordata Subphylum Cephalochordata

PHYLUM HEMICHORDATA

marine worms
with apparent links to chordates on the one hand and to echinoderms on the other
Chordates: (+) pharyngeal slits, embryonic invagination of nerve cord (-) notochord, postanal tail
Echinoderms: bipinnaria larva of starfish and tornaria larva of balanoglossids, number and formation of coelomic spaces
I. Phylum Hemichordata
A. Class Enteropneusta
B. Class Pterobranchia

Class Enteropneusta

Class Pterobranchia

Dolichoglossus kowaleyskyi
acorn worm

I. Integument: Skin
II. Digestive
- mouth, gill apparatus, hepatic caeca, intestine, anus
III. Reproductive
- gonads
IV. Nervous
- notochord, network of nerve fibers, collar nerve cord
V. Circulatory
- blood vessel, blood, central blood sinus, heart vesicle
VI. Excretory
- skin, glomerulus, nephridia

Dolichoglossus kowaleyskyi
acorn worm

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