﻿XO. 7 EMERITA ANALOGA WEYMOUTH AND RICHARDSON 5 



While the wave is in, Emerita may often be seen swimming about 

 close to the surface of the sand, but as the wave recedes they bury 

 themselves. This behavior suggested to us that they might follow the 

 movements of the tide up and down the beach so as always to be within 

 the wash of the waves, but as already stated observations failed to 

 show that this took place to any marked degree. 



If they are turned out with a spade, they burrow into the water- 

 saturated sand with astonishing rapidity. They are unable to burrow 

 readily in the dryer sand farther up the beach and when placed upon 

 it cover themselves only after several attempts. Their method of 

 burrowing may best be observed by placing them in a dish containing 

 a shallow layer of wet sand. By reference to figs, i, 2 and 3, pi. 1, 

 it will be seen that the general form of the body is ovoid, and that the 

 dactyls of all the legs are flattened and expanded to serve as digging 

 organs. In burrowing, Emerita invariably moves backwards, 8 stirring 

 up the sand with some of the appendages while pushing and swimming 

 backwards with others until it is covered. The detailed action of the 

 parts involved is somewhat as follows : the uropods, which appear to 

 be the most important, strike upwards and forwards in unison tending 

 to throw the loose sand upon the back, or, where the sand is firmer, to 

 force the body downward and backward. The four large pereiopods 

 take part in the process in varying degrees, apparently in each case 

 acting alternately. The last pair, which, it will be noted, are directed 

 backward along the sides of the body (fig. 3, pi. 1), move laterally, 

 pushing the sand to each side. The two middle pairs act much as in 

 walking, that is, in such a way as to thrust the body backwards, the 

 broad trowel-like dactyls serving to catch in the sand. The flattened 

 first pair of pereiopods corresponding to the chelipeds of allied 

 forms, which are held forward, are used to scull the body backward, 

 so that under the combined action of all these appendages the animal 

 is carried diagonally downward and backward until the anterior end 

 of the carapace is just covered. Emerita seldom goes more than a few 

 millimeters below the surface except when trying to escape or under 

 unnatural conditions, and usually remains with some of the append- 

 ages exposed in a manner soon to be described. When burrowing 

 they always work against the current and consequently, as the wave 

 runs off, are left facing the sea — a position of some importance in 

 connection with their feeding habits. 



"This species [Emerita talpoida] burrows like a mole, head first, instead 

 of backwards." Verrill, Report U. S. Fish Commission for 1871-72, p. 338. 1873. 



