PELAGIC FAUNA 



83 



measures between seven and eight centimetres in length and has a whitish 

 colour with rust-red markings. At the posterior end is a button-shaped 

 light organ. But the strangest feature of Spirula spirula is an internal, 

 spiral calcareous shell with a series of gas-filled chambers. The shells are 

 very buoyant and are often washed ashore in large numbers, but the 

 creature itself had rarely been seen until the Dana caught nearly a 

 hundred specimens in the Atlantic and as many again in the Indian 

 Ocean and the Pacific. We also caught many of them, and one evening 

 in the Indian Ocean we took some live ones, which we were able to watch 

 swimming about in the aquarium in their characteristic position, bottom 

 up. We managed to film one of them in motion, actively moving up and 

 down and from side to side until it succumbed to the fierce heat of the 



The black deep-sea cephalo- 

 pod Vampyroteuthis in- 

 fernalis, which lives at 

 depths of 1,000-2,000 

 metres. The white spots ar 

 light organs. 



