132 



LOWER COASTAL ANIMALS 



Coloconger eel chasing the prawn Nematocarcinus. South-west Africa, yoo metres. 



nothuridce come on deck they look like pancakes. Their skeletons are so 

 weak that the body is sustained only by the water in the body cavity, and 

 when that is pressed out the animal collapses. These creatures have to be 

 carefully handled, as some of the species are poisonous and people have 

 died after touching them. However, there are indications that it is espe- 

 cially some of the shallow- water forms (one species has been taken in 30 

 metres of water) which are so toxic, for though we repeatedly had rich 

 hauls of these animals on deck we fortunately experienced no case of poi- 

 soning. Conscious of the possibility of poisoning, we were always cautious 

 about putting our hands into' the mud which came up from the depths. 

 Rubber gloves were very useful, in spite of the discomfort of wearing them 

 in tropical heat. 



There is not much to be said about the molluscs found at these depths. 

 As a general rule, their shells get thinner with increasing depth. As for 

 sponges, these — and especially the glass-sponges — become commoner. 

 The commonest glass-sponges (Hyalonema) are flat, bowl-shaped, or 

 funnel-shaped organisms at the end of a stout stalk through which runs 

 a sheaf of siliceous needles which may be as much as 20 — 30 centimetres 

 long. When the stalk is broken, as in the trawl it invariably was, these 

 needles give a nasty prick. Sorting was rendered even more difficult by 



