Peanut Worms (Order: Sipuncula)

Description: Peanut worms don’t have the obvious segments along their body but do have two main parts of their body - the bigger trunk and the thinner neck called an introvert. This makes them still part of the segmented worm phylum (Annelida). Pacific peanut worms (Phascolosoma agassizii) are multiple shades of brown with purple-brown spots and stripes on the introvert. They are about 12 cm long and just over 1 cm wide. The bushy-headed peanut worm (Themiste pyroides) is medium brown with a lighter brown introvert. The introvert has many small brown spines along it, but may be hard to see. They can be much larger than the Pacific peanut worm at 20 cm long and 5 cm wide.

Habitat: These peanut worms like to live under rocks, in cracks, or in gravel areas. Sometimes they’ve also been found living in rock burrows previously dug by piddock clams that have since died. They are often in the low intertidal to shallow subtidal zones. The Pacific peanut worm ranges from Alaska to Baja California, Mexico. The bushy-headed peanut worm is found from British Columbia, Canada to Baja California, Mexico.

Diet: The short tentacles at the end of the introvert are used for collecting detritus to feed on.

Tide Pool Tidbits:

• With modern genetics, we’re learning more and more about how different species are related to each other. Recently we’re learning that peanut worms may be closer related to or even part of the segmented worm phylum.

References: The New Beachcomber’s Guide to the Pacific Northwest by J Duane Sept, State of Washington Department of Ecology