THE HABITS OF SOME TROPICAL CRUSTACEA: 11 



By R. P. COWLES 



(From the Department of Zoology, College of Liberal Arts, 



University of the Philippines) 



THREE PLATES AND 2 TEXT FIGURES 

 FEEDING HABITS OF ATYA MOLLUCCENSIS AND CARIDINA SPECIES 



At least one species of the genus Atya and several species of 

 the genus Cariclina are found in the fresh-water streams of the 

 Philippine Islands, but these crustaceans are of almost no com- 

 mercial value, although they are sometimes eaten when food is 

 very scarce. Their habits, however, are very interesting, and I 

 consider it worth while to publish my observations along this 

 line, especially since the accounts published for other species 

 are somewhat at variance. 



Both genera are characterized by the possession of remarkable 

 chelae (pincers) on the first and second legs, and to these struc- 

 tures various functions have been ascribed. The peculiarly 

 shaped chelae are provided with dense groups of hairs, which 

 when the chelae are closed remind one of a wet camel's hair brush 

 from which the excess water has been pressed so that the tip is 

 pointed. Some observers of Atya have seen these brushes, when 

 the fingers were open, spread out into the form of a fan under 

 which condition they acted as a sieve to catch minute organisms. 

 On the closure of the fingers the fan was seen to assume the 

 form of a brush, closing around the food and compressing it 

 into a pellet, which was passed to the mouth with great rapidity. 

 Also it has been stated that members of the family Atyidse use 

 the brushes in sweeping up minute particles of food from the 

 mud, and one observer states that the chelae are used for digging 

 burrows. Finally, it has been suggested that it is highly prob- 

 able that all species of the family Atyidae use the bunches of 

 hairs in the form of fanlike sieves for food gatherers as de- 

 scribed above. 



I have had the opportunity of collecting atyas from a moun- 

 tain stream near Manila and caridinas from streams in different 

 parts of the Philippine Islands. Also I have observed the feed- 

 ing habits of atyas in aquaria and of caridinas both in their 

 natural habitat and in captivity. All the species of Caridina 



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