68 
shut, but when the tide returns the roof like structure opens and the 
“casting nets” as seen in our illustration, are protruded and with- 
drawn incessantly. These feathery appendages are the means by 
which the barnacle obtains its food, for they are constantly combing 
out of the water the microscopic animals which exist in millions 
in the sea. 
Lobster. — To the town dweller the word “lobster" induces 
thoughts of a skewer, a mat-basket and a fiery-red creature, reposing 
on its tail. But how similar is this scarlet object to that animal 
when it was in the sea and “monarch of all it surveyed?" Then 
our lobster was a deep prussian blue colour delicately mottled with 
pinkish white. There it crawled over and under the rocks in search 
of food until one day it found a very tempting morsel right inside a 
lobster-pot. Shortly after that it quitted the ocean for ever and 
finished its earthly career in the usual way. Whenever a lobster is 
threatened with danger, instead of rushing forward to escape, it 
stretches out wide its tail and curves it under its body with such a 
jerk that the creature flies backwards for a foot or more with amazing 
rapidity. If still threatened this process is repeated until, still 
backwards, it reaches some retreat into which it clumsily shuffles, 
leaving only the formidable pincers visible. From this position it is 
very difficult to dislodge, if only a frontal attack be possible. 
Common Prawn and Shrimp. — Like the lobster, the prawn 
completely changes its colour during the culinary process, turning 
from a transparent bluish to an opaque reddish tint. The shrimp, 
on the other hand, becomes a dark brown colour on boiling. Hosts 
of young prawns are captured annually and sold as shrimps ; but 
these are invariably pink, while the true shrimps are always a 
greyish brown when cooked. Prawns delight in weedy rock pools, 
while shrimps prefer sandy areas. The two may be distinguished 
from one another quite easily when it is remembered that the prawn’s 
head is furnished with a sawlike horn, while that of the shrimp lacks 
anything of this nature. The bodies of dead animals constitute 
their chief food. 
Hermit Crab. — It is quite a common sight to see a whelk, or 
perhaps a winkle, travelling along the bottom of some rock-pool at 
a surprising rate for so sluggish an animal. If picked up the 
supposed whelk will immediately seek refuge in the most remote 
part of the spiral shell, leaving the unmistakable pincers of some 
crustacean exposed to view. This creature is the Hermit Crab, whose 
body is so soft that it is obliged to protect it by living in the cast-off 
shell of some mollusc. The limbs are quite hard, like those of other 
crabs, but the body is merely covered by a soft skin. This crustacean 
manages to hold on to its house by means of powerful clinging 
appendages on its tail. Wherever the hermit wanders the shell 
accompanies it, for it never quits its domicile until it has outgrown it 
and found a better. 
Thornback and Spider Crabs. — These two crustaceans are 
similar in appearance, but the pincers are very long in the former, 
while in the latter they are rather small. Both are admirably pro- 
tected when crawling about among the seaweeds at the bottom of the 
sea, for their backs and the dorsal portions of their limbs are densely 
covered with short stiff bristles. These hairs, in course of time, 
become clogged with the growing fronds of marine plants, minute 
sponges and acorn barnacles. When covered in this way, it is a very 
difficult task to discover one of these creatures in its habitat, espe- 
cially in the uncertain light which prevails at that depth of water. 
