178 ANIMALS OF LAND AND SEA 



which they sweep small animals from the sea water. These 

 feather-like structures, together with the color, which re- 

 sembles that of a barnacle goose, taken in connection with the 

 fact that this goose was not known ever to lay eggs — its 

 nests have only recently been discovered, in for a goose most 

 unlikely places — gave rise to the idea of the connection be- 

 tween the two. The barnacles are crustaceans, related to the 

 copepods. In their young stages they are quite like other 

 young crustaceans, but they undergo profound changes during 

 growth. Some barnacles, which live on whales, bore deep into 

 their skin to attain a better anchorage. Others bury themselves 

 in the outer layer of sponges. Many others, become para- 

 sitic, when young bore into crabs and other larger crustaceans 

 and, losing all semblance to others of their kind, develop a 

 mass of roots through which, plant-like, they absorb the juices 

 of their host. 



The sea-peaches and other large sea-squirts are familiar 

 to all fishermen on our coasts. They have a sieve inside of 

 them by means of which they strain small organisms from the 

 water after the manner of the salps. 



The brachiopods, which look like bivalve molluscs but are 

 really very different, mostly live attached, though a few burrow 

 into mud. Their food collecting mechanism is in general simi- 

 lar to that of the polyzoans and phoronids to which they are 

 supposed to be related. One of them, called the snake's head, 

 is very common in suitable localities on the New England 

 coast below the low tide mark. 



Some bivalve molluscs live attached to firm supports, like the 

 oysters of our shores, while many others, like the clams and 

 razors, live buried in the mud. Some, like the mussels, attach 

 themselves with slender silken threads, as all do when very 

 young. The quahogs or hard shelled clams, from which the 

 Indians used to make their wampum, and other forms lie 

 exposed in quiet places on the bottom. A few, hke the sea- 

 dates or pholads, bore into rock and sometimes in great num- 

 bers into breakwaters, while the ship-worms or teredos, which 



