DEPARTMENT OF MARINE BIOLOGY. 207 



III. Chemistry of Pigment of the Blue Starfish. 



In the surface cells of the blue starfish. (Linckia laevigata) there occurs a 

 blue pigment, diffuse throughout the cells and also in the form of large darker 

 blue granules, which has the peculiarity of turning red in alcohol and dis- 

 solving. Many Crustacea contain the same sort of pigment. The surface of a 

 large number of dried starfish was filed away and the blue powder was pre- 

 served for ultimate purification and analysis of the pigment. Only a few pre- 

 liminary observations have thus far been made. 



In acetone, ether, chloroform, ?i/5 NaOH, and alcohols, the red compound 

 is formed; in glycerin, 40 per cent formaldehyde, and n/5 HCl, the blue com- 

 pound remains unchanged. 



In water, the blue pigment dissolves and can be filtered clear, if a little acid 

 is added to dissolve the CaCOs. A slight amount of alkali changes the color 

 to red orange, but the blue does not return in acid. 



A blue water solution decomposes on boiling to compounds of a dirty straw 

 color. A blue water solution shaken with ether, chloroform, or benzol is 

 turned red and none of the red is absorbed. If the ether or chloroform is 

 evaporated, the blue color returns. An alcoholic solution, however, remains 

 red on evaporation to dryness. 



Both red and blue color varieties gradually bleach in sunlight. 



Rejport upon Color of Fishes of the Tortugas Reefs, by W. H. Longley. 



The study of the reef-fishes of Tortugas in the season of 1914 has led to 

 the recognition of a number of interesting facts. The first concerns a small 

 group of five species, belonging to three famihes, and including all the truly 

 red fishes of which I have obtained full-grow^l specimens in the shallow water 

 of the inner reefs. These are the squirrel-fishes, Holocentrus siccifer, ascen- 

 sionis, and tortugce, together with A7nia sellicauda and Priacanthus criientatus. 

 Their conspicuousness under certain conditions is unquestionable. 



These red fishes have one striking habit in common. All lurk in sheltered 

 crannies of the coral heads during the day and emerge from them at night. 

 T\vice duri)ig a month of close observation, I saw a specimen of H. siccifer 

 beyond the shelter of the reef for a short period during the day, but never saw 

 any individual of any other of the five species so exposed. Not infrequently, 

 however, the snout, tail, or large eye of Priacanthus may be seen through a 

 crevice, or even the whole body of a squirrel-fish in the depths of one of the 

 deeper narrow clefts in the coral. But I have taken six individuals of four 

 species with a single charge of dynamite and rarely failed to obtain some when 

 blasting among the heads. Again, one may see, after dark, in the vicinity of 

 the same heads which seem uninhabited by them during the day, more red 

 fishes than there are of all other species combined. Finally, the unusually 

 large eyes of these fishes suggest that they are accustomed to living in light 

 of low intensity. 



In view of the facts noted, I consider it highly probable that the red pigment 

 of these fishes has the same biological significance as that of the many red 

 animals living at great depths where the light-waves have been very largely 

 absorbed by the water through which they have passed, and that in neither 

 case does it minister to the conspicuousness, but rather to the inconspicuous- 

 ness, of the animal displaying it. 



A second series of facts concerns the modification of color pattern within 

 the limits of a family. Both in the snappers (Lutianidae) and grunts (Hsemuli- 

 dae) there are generalized patterns which, by the reduction or extension 



