CHAP. XII SCYPHOZOA — SCYPHOMEDUSAE 3 I I 



forms, such as the common Aurelia, Pelagia, Cyanaea, are usually 

 of a uniform pale milky -blue or green colour. Generally the 

 colour is uniformly distributed, but sometimes the surface of the 

 umbrella is freckled with irregular brown or yellow patches, as in 

 Dactylometra and many others. There is frequently a special colour 

 in the statorhabs which renders them, conspicuous in the living 

 jelly-fish, and the lips, or parts of the lips, of the manubrium 

 have usually a different colour or tone to that of the umbrella. 



There is no reason to believe that the general colour of any 

 of these jelly-fishes has either a protective or a warning signifi- 

 cance. Nearly all the larger species, whether blue, green, or 

 brown in colour, can be easily seen from a considerable distance, 

 and the colours are not sufficiently bright or alarming to support 

 the belief that they can serve the purpose of warning either fish 

 or birds of the presence of a dangerous stinging animal. It is 

 possible, however, that the brighter spots of colour that are often 

 noticed on the tips of the tentacles and on the lips may act as 

 a lure or bait in attracting small fish and Crustacea. 



Some of the Scyphozoa are phosphorescent, but it is a singular 

 fact that there are very few recorded observations concerning the 

 phosphorescence or the absence of it in most of the species. The 

 pale blue light of Pelagia noctiluca or P. phosphora can be re- 

 cognised from the deck of a ship in the open ocean, and they 

 are often the most brilliant and conspicuous of the phosphorescent 

 organisms. 



The food of the Scyphozoa varies a good deal. Charyhdea 

 and Periphylla, and probably many others with large mouths, 

 will capture and ingest relatively large fish and Crustacea ; but 

 Chrysaora isosceles'^ apparently makes no attempt to capture 

 either Copepoda or small fish, but preys voraciously upon Antho- 

 medusae, Leptomedusae, Siphonophora, Ctenophora, and pelagic 

 worms. Very little is known about the food of the Ehizostomata, 

 but the small size of the mouths of these forms suggests that their 

 food must also be of minute size. The frequent association of 

 small fish with the larger jelly-fish is a matter of some interest 

 that requires further investigation. In the North Sea young 

 whiting are the constant guests of Cyanaea capillata? Over a 



1 M. J. Delap, Irish Naturalist, x. 1901, p. 27. 



2 E. W. L. Holt, Beport on the Sea and Inland Fisheries of Ireland for 190^, 

 pt. ii. 1903, p. xvi. 



