CAROTENOIDS 



almost no carotenes, the main pigments being zeaxanthin and mytiloxan- 

 thin. The latter which is apparently a characteristic acidic carotenoid, 

 occurs only in the free state ; small amounts of a carotenoid similar 

 to Lederer's glycymerin were also noted. 



Both carotenes and xanthophylls were noted in the edible oysters 

 Griiphea angulata and Ostrea edulis ; the visceral mass contains about 

 twenty times as much pigment as the rest of the animals. '^^ 



Strain* ^^ has recently shown that the rose-pink coloration of the 

 nudibranch mollusc, Hopkinsia rosacea, is due to a new carotenoid, 

 Hopkinsiaxanthin (Table 27 and Fig. 25). Although insufficient 

 material was available for a complete chemical study, it appears that 

 this pigment contains two hydroxyl groups and one carbonyl group. 



Table 27. — Characteristic Carotenoids of Marine Molluscs 



REFERENCES TO TABLE 27. 



1. Lederer, E. (1933), C. R. Soc. biol. Paris, 113, 1015. 



2. Lederer, E. (1934), C. R. Soc. biol. Paris, 116, 150. 



3. Scheer, B. T. (1940), Jf. biol. chem., 136, 275. 



4. Strain, H. H. (1949), Biol. Bull. Woods Hole, 97, 206 



Formation and Metabolism 



Scheer's investigation on M. californianus suggests that carotenoids 

 play a positive role in mussel economy. There was no marked seasonal 

 variation in any of the carotenoids and prolonged fasting, up to 196 

 days, resulted in no appreciable change in pigment concentration, 

 although there was a suggestion that mytiloxanthin may be to some 

 extent converted into zeaxanthin. There is, however, a considerable 

 drop in amount of carotenoids present, especially in the gonads, after 



176 



