g8o Marvels of the Universe 
harmonize with the red weeds among which they live, and they attach fragments of the weed to their 
limbs and bodies by means of natural hooks and spines, so that these minute ribbons and laces, 
waving in the water, take off all resemblance to a crab. 
Another genus of Spider Crabs is represented on page 985, in which the limbs, though slender, 
are more proportionate to the size of the body. This is known as Gibbs’ Spider Crab, and his legs 
have swollen joints, which make him look like a sufferer from rheumatic gout. But it is little of 
either legs or body that is seen by his submarine associates, for Nature has provided him with a fur 
of club-shaped hairs, from which spring rows of hooked bristles, which enable him to attach tawdry 
finery in the shape of bits of weed, corallines and living sponges. The individual photographed 
(a female) has induced a mass of sponge to grow upon her back, under which she goes abroad per- 
fectly disguised. This sponge is not stuck on—it probably was when very small—but grown to the 
natural rough coat. Most of the Spider 
Crabs utilize extraneous matters for their 
disguise, and Nature has made the deception 
easy for them. 
Somewhat similar in the extent of two 
pairs of its legs is the Crab whose portrait is 
given on page 981, and which is known to 
the Japanese as the Demon’s-face Crab. The 
resemblance to a grotesque mask of the human 
face is solely due to the front and back elon- 
gation of the upper shell. If you compare it 
with the broader back of the Shore Crab, you 
will find that all the elevations and depressed 
lines of one are repeated on the other; but 
their lateral compression in the Demon’s-face 
Crab produces the effect of lips, broad nose and 
slanting eyes. An allied species is found both 
at Hong Kong and in the Mediterranean, 
Photo by] [E. Step. where the Italians have named it the Knave. 
THE POLISHED CRAB. The shortening of the last two pairs of limbs 
The trunk is thin, narrowed behind and highly polished, and bringing them practically on the back is. 
so that it easily slips down into the sand. 
no doubt due to a habit of holding a sponge 
or other foreign object over its back. This has not been recorded as a fact in the Knave’s economy, 
but the similar arrangement of the corresponding limbs of the Gnome Crab (see page 485) leads 
one to suspect it. 
On our own coasts we have a Crab that is similar in respect of the grotesque human features 
on its back, and they are produced in the same way. This is known as the Masked, or Long-armed 
Crab. In the male, whose photograph is seen on page 983, the first pair of limbs are very long 
(much shorter in the female), and it uses these as levers to push its wedge-shaped body into the 
soft sands in which it takes its rest. It will be noted that the antenne, which in the majority of 
Crabs are very short, are here as long as the body. In ordinary these are used by Crabs 
as sense organs, much as the cat’s whiskers are said to be used, to obtain impressions of their sur- 
roundings. But in the case of the Masked Crab they have undergone a remarkable modification to 
fit them for an entirely different purpose, necessitated by the crab’s peculiar habits. Looked at 
closely, each of these feelers will be seen to have along its inner face two rows of stiff hairs, and when 
the antenne are brought close together, side by side, the hairs of both interlock and so constitute a 
tube. When the Crab has buried itself deeply in the sand, the tips of these antenne stick out into 
the water above, and down the tube the Crab draws water to supply its gills, channels under the 
