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Phylum Hemichordata Acorn Worms Phylum Hemichordata.

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Presentation on theme: "Phylum Hemichordata Acorn Worms Phylum Hemichordata."— Presentation transcript:

1 Phylum Hemichordata Acorn Worms Phylum Hemichordata

2 Phylum Hemichordata Defining characteristics
A conspicuous dorsal extension of the pharynx forms an anterior buccal tube or stomochord Phylum Hemichordata

3 Acorn Worm Habits 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

4 Tube Dweller Phylum Hemichordata

5 Body Structure Body is divided into three parts: Proboscis, collar, and trunk The anterior end is a muscular, extensible proboscis used to burrow and collect food A slender stalk supported by cartilage skeleton joins proboscis to collar The trunk is behind the collar and has many pairs of small external gills slits through which water exits Mouth is located at the proboscis collar junction, which directly leads into a pharynx Phylum Hemichordata

6 Body Structure Phylum Hemichordata

7 Feeding Phylum Hemichordata

8 Internal Transport Possess a true circulatory system
The blood lacks pigment and runs in dorsal and ventral blood vessels Phylum Hemichordata

9 Reproduction Fertilization occurs in the water and forms a feeding planktonic larva Tornaria Phylum Hemichordata

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