364 



THE AMERICAN MUSEUM JOURNAL 



for reproductive elements. Each female 

 lays annually from ten million to fifteen 

 million eggs. In the Menemsha mussel 

 community there are some thirty-six 

 million individuals. If half the number 

 is reckoned as females and we assume 

 each one to lay an average of ten mil- 

 lion eggs, we should have resulting 

 18,000,000 times 10,000,000 eggs which 



The oyster drill (above) likes mussels better than 

 oysters. Its toll of victims ranks second to that of 

 the starfish only 



The dog whelk (below) is very fond of mussel flesh 

 and may become an able assistant to the oyster drill 

 in exterminating a colony of mussels 



is 180,000,000,000,000 — which repre- 

 sents the possible number of offspring 

 that can be produced in one year by 

 the Menemsha mussel community. The 

 eggs develop at a phenomenal rate, 

 producing free-swimming embryos with- 

 in five hours after fertilization. At the 

 end of three to five days the shell is 

 formed and the young mussels that are 

 fortunate enough to have escaped the 



jaws of numerous voracious beasts of 

 prey and to have been carried by the 

 tidal currents to favorable situations, 

 now settle on stones, seaweeds and 

 other solid objects, where, after creep- 

 ing about for a time, they attach them- 

 selves by means of the byssus and 

 start a new colony. Under favorable 

 conditions they grow rapidly, the growth 

 often amounting to more than an inch 

 a year for the first two or three years. 

 After that there is a rapid decline in 

 the rate of growth. 



Associated with the mussel commu- 

 nity, there are usually found numerous 

 plants and animals that add much to it 

 in the way of beauty and general inter- 

 est. Rockweed often gracefully over- 

 hangs portions of the bed and sometimes 

 ribbon-like streamers or branching fila- 

 ments of exquisitely colored red, pink, 

 green, and brown alg?e attached to the 

 shellfish, wave to and fro in the water. 

 Beautiful bunches of the delicate pink 

 hydroids, which look like plants but in 

 reality are animals, may be seen clinging 

 to the shells, while sea squirts, sea 

 anemones, sea urchins, sea pork, sponges, 

 corals, barnacles, boat shells and moss 

 animals live in friendly relation with the 

 whole community. This relationship 

 has been most successfully demonstrated 

 in the mussel group on exhibition at the 

 American Museum of Natural History. 

 Curious looking worms of various sorts 

 and often of brilliant colors burrow 

 beneath and between the moUusks, and 

 on their shells the serpulids often con- 

 struct tortuous limy tubes. The little 

 periwinkle, Littorina, is nearly always 

 preesnt on the beds in great numbers, 

 especially when eelgrass and algte are 

 growing there in abundance. Green 

 cral)S, rock crabs, spider crabs, and king 

 crabs flit back and forth over the com- 

 munity, busily engaged in the mussel 

 scavenger service. Peeking out from 



