50 THE SCALLOP FISHERY 



CHAPTER IV. — HABITS. 



The story of the scallop would hardly be complete without some 

 mention of its interesting and curious habits, which not only explain 

 the anatomical structure, but also throw further light upon the life 

 history. The methods of life of the young scallop are for the most part 

 different from those of the adult, and are typical of stages in the de- 

 velopment of the animal. A change in the function of an organ causes 

 a corresponding change in its form, and practices once useful are dis- 

 carded for others better adapted to the needs of the growing animal. 

 Throughout early life can be traced a steady development, culminating 

 in the adult method of life. For this reason the habits of the young, 

 with the exception of swimming and resting, have been considered 

 separately in the following chapter, and as far as possible arranged in 

 logical sequence. 



Attachment. 



After the free swimming period of its early existence, one of the most 

 prominent habits of the young scallop is the power of attachment, 

 which occurs at the completion of its embryonic existence. This func- 

 tion not only proves a great help in growth, marking a new era in shell 

 formation, but renders the immature animal less liable to attack from 

 its numerous enemies. 



The Set. — The " set " takes place when the young scallop attaches 

 itself to any foreign object by means of threads secreted from a gland 

 in the foot. The animal, at the proper time, settles or strikes against 

 some object in the water, and clings to the point of attachment with 

 its foot until the thread or byssus is spun. The frequency of " set " on 

 eel grass is best explained by the hypothesis that the swimming scallop 

 at this critical period of its life is carried by the current against the 

 upright blades, where it clings with the foot until the byssus thread 

 is formed. Larger scallops have been observed to swim to the sides of 

 the aquaria and support themselves on the slippery glass by the foot 

 alone until the attachment by the byssus was accomplished. The great 

 numbers of young scallops found on the sides of spat boxes lowered 

 from a raft moored in 20 feet of water show that the means of first 

 attaining this attachment was by clinging with the foot when the animal 

 came in contact with the box. 



Young scallops attach themselves to eel grass, shells, stones, etc., but 

 are generally first noticed by the fisherman on eel grass or sea lettuce, 

 where they remain until they reach adult age. Scallops are found on 

 both the upper and the under side of eel grass, usually 3 to 6 inches 

 from the bottom being the locality of the heaviest set. Ulva (sea 

 lettuce) seems to offer a better place of attachment than eel grass, as 

 it may be carried for miles by the currents and " seed " scallops may 



