PIGMENTS AND COLOURS 



479 



becoming sexually mature, and females after spawning, are bright green. 

 It is at these times that the tissues undergo phagocytosis, and the increased 

 breakdown of haemoglobin is accompanied by a corresponding increase of 

 biliverdin in the body (1 1). 



Biliverdin, found in leeches, results from the decomposition of ingested 

 blood. It is also found in the roots of certain rhizocephalans (Septosaccus, 

 Peltogaster, Parthenopea) where it is derived from blood haemoglobin, 

 when present, or some other haem compound. The fate of haemoglobin 

 in the praniza larvae of gnathiid isopods (Paragnathia formica and Gnathia 

 maxillaris) is interesting in that it determines the colour of the animal. The 

 parasitic stages known as pranizas feed upon the blood of fishes, and are 

 red, green or colourless according to the condition of their gut contents. 

 The colourless animals do not ingest the erythrocytes ; in the red animals 

 the erythrocytes remain intact for a long time ; and in the green animals the 

 erythrocytes are readily haemolysed and the contained haemoglobin 

 decomposed into a green bile pigment. These differences between pranizas 



COOH COOH 



Crl 2 CH 2 CH 2 



II I I 



CH3 CH CH 3 CH 2 CH2 CH 3 CH3 



= 



Nn^ 



=CH-^ N >-CH = 



•N^ 



CH 



^N 



-CH 2 

 — CH. 



O 



BILIVERDIN 



depend upon the fish which are parasitized, the pranizas reacting differently 

 to the blood of different species offish (25, 62, 63, 80). 



Biliverdin has also been identified in anemones and occurs in the green 

 parts of Tealia felina. An interesting substance having affinities with the 

 bile pigments is calliactine, which occurs as red and violet granules in the 

 column of the sea-anemone Calliactis parasitica. The skeletal pigment 

 responsible for the colour of the blue coral Heliopora caerulea is a bilin 

 related to biliverdin, and termed helioporobilin. 



Various pyrrolic pigments have been described in molluscs. Pinnaglobin, 

 found in the blood of Pinna squamosa, has a prosthetic porphyrin group 

 containing manganese. The shells of many molluscs (gastropods and 

 lamellibranchs) contain considerable amounts of pyrrol pigments, includ- 

 ing linear chain tetrapyrrols (bile pigments) and various porphyrins. 

 Uroporphyrin is widely distributed, and has been identified in many marine 

 species, shells of Calliostoma, Pteria, Pinna, integument of Aplysia and Akera. 

 Noteworthy is aplysiopurpurin, a deep purple pigment secreted by special 

 glands on the underside of the mantle in the tectibranch Aplysia. This 



