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Phylum Hemichordata
Acorn Worms
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Phylum Hemichordata
Phylum Hemichordata
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Defining
characteristics
– A conspicuous
dorsal extension of
the pharynx forms
an anterior buccal
tube or
stomochord
Phylum Hemichordata
Acorn Worm Habits


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Rarely found on the surface this group is found in the mud flats of our
sounds and creeks
– Burrow through sediment and ingest it, assimilating what is of
value
Some species remain in mucus lined burrows
Phylum Hemichordata
Tube Dweller
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Phylum Hemichordata
Body Structure
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Phylum Hemichordata
Feeding
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Phylum Hemichordata
Internal Transport
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Possess a true circulatory system
– The blood lacks pigment and runs in dorsal and
ventral blood vessels
Phylum Hemichordata
Reproduction

Fertilization
occurs in the
water and
forms a
feeding
planktonic
larva
–
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Tornaria
Phylum Hemichordata