THE RESPONSES OF SHRIMPS 139 



and though almost every part of the skin of the shrimp, 

 and in particular its legs, is provided with sensitive 

 hairs, and is to some extent sensitive to change of 

 pressure, such as a wave or a movement implies, yet 

 the cars by reason of their position near the brain 

 have a more commanding influence on the whole body 

 — an influence they practise even in times of peace. 



The sense of taste or smell plays such a large part 

 in animal life that we must consider it as a fundamental 

 response ; yet in the shrimp, as in all animals, though 

 so important, this sense has no well-defined organ 

 through which it works. All we know is that certain 

 hairs on the upper lip and antenna?, like those of a cat, 

 act as feelers, by which the neighbourhood of food is 

 recognised. The response of the body to this sense 

 is a complex one. In a chain of concerted action 

 muscular events begin that stretch from one end of 

 the body to the other and engage the activity of many 

 limbs. The food of the shrimp consists of small 

 bivalves, which it finds amongst the sand in which 

 it barrows. The little shell is picked up by the big 

 claws and transferred to the mouth. Here the excite- 

 ment of the upper lip and jaws spreads to the lower 

 lip, and to limbs further back, as well as to parts 

 further inward. The mouth begins to water, that 

 is, the digestive juices are prepared; and so the whole 

 series of digestive processes — the dissolution of the food 

 and its absorption — are linked up as a composite re- 

 sponse to the smell roused by the discovery of food. Yet 

 this response is ultimately referable to the property of 



