Body Fluids 



121 



found in various crustaceans, insects, moUusks, annelids, gephy- 

 reans, echinoderms, and nemerteans. Haemocyanin, which contains 

 copper, is found in various crustaceans, arachnids, gastropods, and 

 cephalopods. Other respiratory pigments are found as folloiiys: 

 chlorocruorin, chaetopods; haemerythrin, gephyreans; chlorophyl, 

 lepidopterous insects; and tetronerythrin, decapod crustaceans. 



Fig. 21. A fresh water crab from Colombia.' 



The occurrence of respiratory pigments is without reference to 

 phylogenetic relationship. Some chironomid larvae which live in 

 stagnant water contain so much haemoglobin that they have long 

 been known as blood worms; others which dwell in well-aerated wa- 

 ters are quite transparent. It has been said that haemoglobin occurs 

 where there is a dearth of oxygen, — often in aquatic habitats on 



