126 LOWER COASTAL ANIMALS 



wanted to catch epifauna, and it was a relief to be able to do so without 

 incurring additional risks. 



I'here are some shallow-water localities which we were able to explore 

 only on rare occasions. They include the entensive pastures of grasswrack 

 (Zostera, Posidonia), which occur in sheltered places both in the Tropics 

 and m temperate regions, and whose fauna is also represented in Nor- 

 thern Europe in the familiar pipe-fish, small snails, etc. They also include 

 the similar expanses of mud or sand with little or no vegetation, like 

 those on our own shallow shores. These tropical expanses closely resemble 

 ours in appearance, and there, too, are places where the shallow water 

 briefly exposes the lowermost part of this fauna. But on a closer inspection 

 we find that the small heaps of sand on these tropical shores are made not 

 by lug-worms but by another, rather remarkable, worm (Balanoglossus). 

 Here also we find the carnivorous moon-snail (Natica), a mollusc which 

 preys on bivalves by burrowing underneath them and drilling a hole in 

 their shells before inserting its proboscis to devour them. The moon-snail's 

 spawn, which is full of grains of sand, lies scattered about the surface. 

 Numbers of starfish rove about here in search of food, and on rather 

 sandy bottoms we find the cake-urchins, whose perfectly flat shape has 

 earned for them the popular name "sand dollars" (Laganum, Peronella). 

 On bottoms of pure sand constantly whirled about by the rough surf we 

 were, for obvious reason, rather chary of venturing. Here there are some 

 tellins and wedge-shells (Tellina, Donax), molluscs which we were occa- 

 sionally fortunate in finding above the surface. They are such rapid 

 burrowers that they were difficult to photograph on the sand; it is to 

 their skill in burrowing that they owe their survival in this rough habitat. 

 There are also some crab-like crustaceans which burrow in these sandy 

 parts. 



On the firm bottom we usually find a much richer fauna, and in fact 

 these are the richest of all marine localities. At the most southerly places 

 visited by us we found, as in Northern Europe, dense growths of algae, 

 though the fauna there was rather poor. On the rocks, in somewhat war- 

 mer regions — for example, off New Zealand and the Californian coast — 

 we found large numbers of animal sponges, sea anemones, polyzoa, tube- 

 building worms, ascidians, etc. Carnivorous animals were running about 

 above; crabs roved among the rocks; top-shells (Turbo), whelks (Murex), 

 cone-shells (Conus), dog whelks (Purpura), and other creatures glided 

 over the bottom. But the most interesting ones, when we succeeded in 

 finding them, were Haliotis. The Maories have for centuries employed 

 the brilliantly coloured mother-of-pearl of these shells as eyes for their 



