PELAGIC FAUNA 



Scarlet deep-sea prawn, a new species of the genus Notostomus, 17 centimetres long without 

 antenna; taken off East Africa at a depth of between 3,400 and 3,800 metres. 



able to rise to upper water levels, though only in colder regions; in warm 

 seas it stays below where the water is cold. The Galathea Expedition 

 also found new species of deep-water medusae. Of the genus Peryphyllopsis, 

 which is related to Periphylla, there was only one known species, of which 

 only two specimens had been seen, one in the eastern Indian Ocean and 

 the other in the eastern Pacific. Both had been found in deep water and 

 were six centimetres in diameter. We now found, between East Africa 

 and the Seychelles, five specimens of a new species of this genus, six 

 times the size of the others; and in the Bay of Bengal, also in deep water, 

 we took one of the largest medusae ever seen, a new species of the genus 

 Cassiopea, nearlv a metre in diameter. 



Crustaceans form a very substantial proportion of the animal popula- 

 tion of the deep. Water fleas (Daphnia) and copepods are ubiquitous 

 and provide an important source of food for other animals. A number 

 of bathypelagic forms of amphipod were found, some with extraordinarily 

 large eyes and others with a long, pointed head. 



When the trawl came up from deep levels we could rely on finding 

 in it brillant scarlet prawns, many of which would be very large. In 

 general form they resemble the prawns of upper water levels and they 

 are not noticeably adapted to life in the deep. A few from the extreme 

 depths are blind. None of these has special light organs, but a few species, 

 including some of the many belonging to the genus Acanthephyra, 

 can envelop themselves in a cloud of luminous matter ejected from a 

 pore under each eye. In the dark this will give as much concealment as 

 the cloud of dark liquid in which a squid hides in the sunlit levels. We 



