Phylum Hemichordata Acorn Worms Phylum Hemichordata

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

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

Tube Dweller Phylum Hemichordata

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

Body Structure Phylum Hemichordata

Feeding Phylum Hemichordata

Internal Transport 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 Tornaria Phylum Hemichordata