l68 ANIMAL LIFE OF THE DEEP SEA BOTTOM 



well-nigh insuperable task to try to provide figures, as it would mean work- 

 ing through all previous reports. 



In the foregoing we took the yield of a single trawl in order to give a 

 picture of life at the great ocean depths. Clearly, it could be filled in 

 with many details from all our other trawls. There were many animal 

 forms which appeared only now and then, so that from a single trawl it 

 is only possible to describe the general features of the fauna. In the deep 

 sea, as in the North Sea, there are animals, such as sea-spiders, which 

 are always so small in numbers that only a few will be obtained even 

 in persistent fishing (Fig. 184). 



But even rare catches have a wide interest beyond the fact of their 

 rarity. We can proceed with the fishes and take an example from the 

 brotulids, the strange Acanthonus (Fig. p. 170). We caught this at 2,620 

 metres in the Gulf of Guinea, along with 15 other bottom-dwelling fishes. 

 We were overjoyed at such an early success; it was our second attempt 

 with the large trawl and we already had a rarity taken only four times 

 previously, the last time by the Norwegian Michael Sars Expedition of 

 19 10. We of course expected it to turn up again soon; but though we 

 obtained many fishes in many trawls at relatively moderate depths of 

 less than 4,000 metres, we did not meet with it again until the Gulf of 

 Panama, at a depth of 3,710 metres, and in the very same region where 

 the third specimen had been caught in 1891. I shall refrain at this stage 

 from drawing far-reaching conclusions from this specimen, but cannot 

 help surmising that Acanthonus needs more food than so many other 

 fishes with a more continuous deep-sea distribution. Hence we found it 

 in the deep in the regions where Professor Steemann Nielsen demonstrated 

 a large food production in the surface layers — off West Africa and west 

 of America. 



One more brotulid, Typhlonus, must be mentioned, first for its appea- 

 rance: an immense swollen head and a small body which, like the long, 

 compressed tail, is pale and semi-transparent (Fig. p. 171). The head is 

 soft, almost gelatinous, and discernible deep beneath the skin are what 

 in the remote ancestors of the fishes were functioning eyes; but Typhlonus 

 is quite blind. On the underside of the head is a horse-shoe mouth which 

 can be protruded almost like a shovel, and it is presumably used for 

 shovelling into the mud when the fish perceives a prey. 



A parallel development is seen in quite a different family, which also 

 belong to the typical deep-sea fishes; namely, the rat-tails (Macr our idee). 

 Of the special and very rare species Macrouroides (Fig. p. 172) we ob- 

 tained only one specimen; and though it was taken in the large pelagic 



