44 SEA-SHORE LIFE 
polyps. Others form hemispherical heads bearing beautiful star- 
like polyps each having eight feathery tentacles, while still others 
form the sea whips and sea fans so characteristic of an Atlantic 
reef. In the sea fans, however, the polyps secrete a horny axis 
which forms the internal framework of the fan and gives a tough 
support for the fleshy parts which cover its surface. Nothing is 
more strangely beautiful than these coral reefs where the rich pur- 
ple sea fans and the chocolate sea whips wave gracefully to the 
surges in the crystal depths, while brilliant fishes glistening in 
green, blue, purple and yellow, glide in and out among the shad- 
ows of the coral caverns. 
The precious coral of the Mediterranean is allied to the sea 
whips. Its polyps are brilliant white, and have each eight feathered 
tentacles; while the internal axis of the colony is red and stony. 
The Brown Sea Anemone, (JMJetridiuwm marginatum, Figs. 19, 
20), is our common sea anemone, which extends from New Jersey 
to Labrador. It is abundant in tide pools, and upon the posts 
and rock work of wharves in Long Island Sound, but it attains 
a much larger size and more brilliant color north of Cape Cod. 

Fig. 20. BROWN SEA-ANEMONE, Contracted. Showing the white 
thread-like filaments called acontia which are extruded 
as a means of defense. 
Although usually brown in Long Island Sound, individuals of 
a pure white, delicate salmon-pink, or olive, are common at Newport 
