ANIMAL LIFE OF THE DEEP SEA BOTTOM 163 



.'ovJ if . 



Fishes, even in the deep-sea, are troubled by blood-sucking leeches. Tasman Sea, 

 3,840 metres. 



when getting in the trawl, and even then the horrid fragments caught 

 in the meshes would stick in our fingers like splinters of glass. The stalks 

 are twisted silica strands, very strong and rope-like. Deep-sea barnacles 

 (Scalpellum), sea-anemones, and other polyps would find in them a wel- 

 come anchorage, raised above the bottom ooze. 



There was another single-stalked animal form which occurred in fairly 

 large numbers, a greyish, insignificant-looking sea-squirt. This creature 

 lives by filtering microscopic organisms from the water, and so it must 

 be raised above the bottom to avoid having its filtering organ blocked 

 with mud if a large sea-cucumber should plough its way past. 



Some of the bristle-worms are rather dull-looking creatures, but our 

 specialist, Mr. Jorgen Kirkegaard, is sure to get something out of them, 

 because there were many species and careful picking of the meshes pro- 

 duced quantities of them after every trawl. Their very numbers make 

 them highly important because, here as in the sea elsewhere, they are a 

 favourite food of fish and other larger animals. So also are bivalves, of 

 which there were fi\'e different species, including some tender little scal- 

 lops which must be regular tit-bits. Among other molluscs were a number 

 of tusk-shells (Dentalium), and four species of snails, of which at least 

 three must be considered carnivorous. 



We come now to the crustaceans. The crabs were quite obviously from 

 the bottom. There are, it is true, some swimming crabs, which may occur 

 in the free water masses, but the creatures here were typical deep-sea 

 crabs (Ethusa) (Fig. p. 149), blind and pallid. From the fact that a female 

 had orange-yellow eggs under the tail we may infer that their life history 

 includes a free-swimming larval stage like that of shallow-water crabs. 

 Not even jn the deep sea do crabs escape their insidious parasites, the 

 strange sac-like creatures which attach themselves under the crab's tail 

 (Fig. p. 149). Only a close study reveals the fact that these also are 

 crustaceans. All that is \isible externally is the sac, but inside the miserable 

 crab is is a system of finely branched roots. The crab is not actually killed, 



