LIFE IN THE OCEAN — CLARK 385 



intermixed with other types modified from them, borne upon a flat- 

 tened, wandlike or treelike support. The units vary from very 

 small, in the hydroids and millepores, to an inch or so in diameter; 

 in the noncolonial forms they may be more than a foot across. The 

 stinging organs, which paralyze as well as sting the prey, enable the 

 ccelenterates to use as food much larger and stronger creatures than 

 do any other of the animals which feed in this way, and they are 

 wholly carnivorous. 



The ccelenterates support many parasites, especially crustaceans, 

 which live within their bodies or travel up and down their stems 

 appropriating the food which they have collected, and brittle stars, 

 especially adapted for clinging to them, while many animals attach 

 themselves to them which are known to live nowhere else, yet which 

 do not feed upon them, like certain anemones. Many small fishes 

 and other creatures live among their branches, protected from their 

 enemies by their stinging tentacles, while a wealth of different types, 

 especially worms and mollusks, hide themselves away in the stony 

 bases of the large corals. 



A. group of colonial ccelenterates, the so-called siphonophores, in- 

 cluding the Portuguese man-of-war, one of the most formidable of 

 all the jellyfishes on account of its unusually developed stinging 

 powers, and a group of colonial tunicates, have adopted an oceanic 

 life, and all the species drift about as true elements of the oceanic 

 fauna. 



Besides these colonial attached animals, there are many others 

 which live attached, but never form colonies, though many are highly 

 social. 



The most familiar of these are, perhaps, the barnacles, some of 

 which, like acorn barnacles, live closely appressed to rocks, piles, the 

 carapaces of sea turtles, etc., while others, like the goose barnacles, 

 formerly supposed to be the young of the barnacle goose, are stalked 

 and are most frequently seen on floating bits of wood, on the bottoms 

 of ships, and about the mouths of whales. 



The barnacles have several pairs of curved feathery appendages 

 with which they sweep small animals from the sea water. These 

 featherlike structures, together with the color, which resembles 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 dis- 

 covered in, for a goose, most unlikely places — gave rise to the idea of 

 the connection between the two. The barnacles are crustaceans re- 

 lated 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 layers of sponges. Many others, become parasitic, when 

 young bore into crabs and other large crustaceans and, losing all 



