CHAPTER XIV 



The Peanut Worms 



( PI I \lu nt Sipu uni lo/'dca) 



To 



__0 a group of about 250 different species of sed- 

 entary marine worms the name "peanut worm" has 

 been applied, although the extended animal resem- 

 bles more a baseball bat with a crown of food-collect- 

 ing tentacles at the small head end. Yet, if disturbed, 

 the worm suddenly shortens, pulling in the anterior 



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half or third of its body, and rounding out to an ap- 

 pearance remarkably like that of the edible part 

 (seed) of a peanut. 



The most striking feature of these worms is the 

 slender anterior part of the body (the introvert), 

 which rapidly and smoothly runs in and out of the 

 larger, cylindrical, posterior part. Actually the intro- 

 vert turns in like the finger of a glove or the wall of a 

 slender balloon pressed at the end by a lead pencil. 



An undisturbed peanut worm extends its introvert 

 from the opening of the burrow and sweeps the mu- 

 cus-covered tentacles over the sea bottom, collect- 

 ing microscopic plants and other bits of nourishment. 

 These are digested in a long intestine which is both 

 looped upon itself to open at an anus well forward on 

 the animal's ventral surface and also spirally twisted 

 within the body cavity. 



Most sipunculoids live in shallow water, but some 

 have been found in depths greater than fifteen thou- 

 sand feet. Many peanut worms live in holes in sub- 

 merged rocks. Sipiinciiliis luidiis reaches a length of 

 about 8 inches and a diameter of Vi of an inch along 

 sandy coasts of southern California, Japan, Europe, 

 and Florida. Golfingia (Phascolosoina) imirgarit- 

 acea of more northern shores in both the Atlantic 

 and the Pacific is more slender but may be 14 to 18 

 inches long. All peanut worms develop from an ac- 

 tive swimming larva (trochophore) and discharge 

 their eggs or sperms through their excretory tubules 

 ( nephridia ) from the body cavity into the sea, where 

 fertilization takes place. 



The peanut worm Colfinn,ia { Phascolosoina ) loses its 

 similarity to a peanut as soon as it extends from the 

 contracted position. Here the smaller front end is 

 being everted into the sand, turning inside out like a 

 finger of a glove. (Oregon. Ralph Buchsbaum) 



