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