ANIMAL LIFE OF THE DEEP SEA BOTTOM l6l 





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A sea-urchin (Echinosigra paradoxa), the most remarkable of all sea-urchins, with the mouth 

 at the end of a neck-shaped extension. (After description by T. Mortensen) . 



deep-sea ooze like lug-worms or the sea-cucumbers we know from shallow 

 water. The aqueous tissues and the low temperature probably enable the 

 sea-cucumbers to live without much food. Probably also they have 

 scarcely any foes, and only in one species did we find parasites in the form 

 of roundworms. 



Along with the sea-cucumbers another main group of echinoderms 

 dominated the picture; namely, the brittle-stars. Whereas the sea-cucum- 

 bers impressed us by their size, the brittle-stars were more strikng for their 

 numbers. In this trawl there were no fewer than 58 specimens, and some- 

 times we would get as many as several hundred. Considering the brit- 

 tleness of their arms, which break at the slightest pressure, many times that 

 number must have fallen in bits and pieces through the meshes of our 

 trawl, both during the dragging along the bottom and the prolonged haul- 

 ing in. It is still difficult to say how many species there were, but the bulk 

 of those taken in this trawl (54) belong to a family, Ophiolepididce, which 

 is "svell represented in the deep sea. The number of species of this family 

 dwelling deeper than 3,000 metres has been reckoned at 49, or just as 

 many as in the other five deep-sea families together. 



Except for the fact that these brittle-stars are invariably pale in colour 

 and even white, they bear a close resemblance to the shallow-water species. 

 The species which, later in the expedition, we found deeper down — in 

 the Kermadec Trench — is, moreover, fairly closely related to a couple 

 of our commonest species in the North Sea and Kattegat, though it lives 

 at 6,660 metres and is evidently common. There were 177 specimens of 

 the species in the trawl from the Kermadec Trench. 



