l6o ANIMAL LIFE OF THE DEEP SEA BOTTOM 



too warm for our energy to be at its highest, the air being 30° C and the 

 surface water nearly as warm. 



Our large otter-trawl with a span of 32 metres had been paid out on 

 7,440 metres of wire, the angle of surface and wire had been maintained 

 at about 58°, and, having towed at a speed of about 3.2 kilometres an 

 hour, we had calculated that the trawl had been on the bottom for three 

 hours. Paying out and hauling in took seven hours. The trawl had gone 

 out at 2 p. m., and so it was dark night when it came up again at a 

 quarter past twelve. Tubs and trays stood ready to receive the catch on 

 the quarter-deck, and all lights were on. Expectations were high, as we had 

 already made good trawls at similar depths in this stretch between Mada- 

 gascar and Mombasa, and at the surface water there was a teeming life 

 of which we had caught a good deal by angling and dip-netting during 

 the trawling. 



The bag was undone and the contents distributed among the biggest 

 tubs. It was well smeared in light-coloured globigerina ooze, because in 

 the outermost part of the bag we had placed a plastic bucket with the 

 deliberate intention of scooping up some of the bottom material contain- 

 ing the smallest animals. Many delicate creatures which would otherwise 

 have suffered from the dragging of the trawl were thus brought up intact, 

 wrapped in the fine clay. 



The soft and slimy sea-cucumbers, paradoxically called echinoderms 

 ("spiny-skinned") were in the majority. There were 30 of them, spread 

 over at least seven different species, though two kinds predominated: the 

 large Psychropotes, 20 — 30 centimetres long (eight specimens), and the 

 white Deima, 10 — 15 centimetres long (eight specimens). Both Psychro- 

 potes and Deima belong to a special order of sea-cucumbers, the Elasipoda, 

 which have their main distribution in the deep sea. They are quite hand- 

 some to look at as long as they are fresh; but like the aqueous tissues of 

 jellyfish they contain a large quantity of fluid, and so are difficult to 

 preserve in alcohol or formalin, which particularly affects their colour. 

 Psychropotes as caught here had delicate reddish-violet hues, one having 

 a lemon-yellow back. Mr. Bent Hansen, our specialist in sea-cucumbers, 

 had a busy time making notes, drawing sketches, and copying the colours. 

 Psychropotes is a singular creature, with its semi-cylindrical body and its 

 great tail appendage rising like a sail behind it. This may possibly be 

 used as a weak swimming-organ, though it is more probable that the 

 animal ploughs its way forward through the deep-sea ooze, when the tail 

 appendage will stand out above the bottom and serve as a kind of respi- 

 ratory organ (Fig. p. 159). The creature gets its food by gorging on the 



