WORMS AND POLYZOA 75 



like most other worms it also lays eggs which pass through 

 a complex metamorphosis. 



A few of the Ribbon Worms make tubes and burrows. 



To the great order of Bristle Worms (Polychata) belong 

 a large number of species of considerable importance to 

 man since they form the staple substance of many food 

 fishes, and are in great demand as bait. All have the 

 bodies made up of many rings or segments, each segment 

 bearing paired limbs armed with stiff sharply-pointed 

 bristles adapted to such varied purposes as swimming, 

 burrowing, feeling, feeding and even breathing. These 

 worms show bizarre forms and resplendent colouring — 

 some of the most striking being common inhabitants of 

 our home waters. 



The Bristle Worms are divided into many families, 

 but here only a number of the more important species 

 can be touched upon. The Common Lug Worm 

 (Aretiicola marina) is sufficiently well known to every sea 

 angler. It attains to some eight inches in length and makes 

 a U-shaped burrow one to two feet deep. It passes many 

 yards of sand through its body daily, in the manner of an 

 earthworm, the waste sand forming the well-known 

 castings after the worm has extracted all nutritive matter. 

 Like the earthworm it does much to sweeten and circulate 

 the soil in which it lives and it has been calculated that 

 these worms in a single acre of sand may throw up 2,000 

 tons of waste matter in the form of castings in a single 

 night. 



The Rag Worm (Nereis diversicolor), another popular 

 " bait," frequents somewhat more gravelly ground, where 

 it often builds a tube on the inner side of some boulder. 



