892 Marvels of the Universe 
SEA-SPIDERS 
BY JOHN J. WARD, F.E.S. 
THE Water-spiders of the pond are true spiders which have developed aquatic habits, but such 
cannot be said of the Sea-spiders ; indeed, it is a question whether they have any claim at all to the 
title of spider. Their anatomy proves them to be a complex zoological puzzle, and perhaps their 
greatest resemblance to spiders lies in the fact that they possess four pairs of conspicuous jointed 
legs and mouth appendages bearing a superficial likeness. 
When we come to examine their anatomy in 
detail, however, then at once difficulties begin to 
arise. The most striking feature is that the large 
abdomen, so characteristic of spiders, is reduced 
to a tiny structure so small as to be scarcely 
noticeable. The apparent body-trunk is not a 
body at all, but consists of four rings to which 
the legs are attached. If we think of a spider 
without an abdomen, and with that part to which 
its eight legs are attached divided more or less into 
four segments, each of which carries a pair of 
eight-jointed legs bearing a single claw, and which 
legs may vary in size from about the length of the 
segmented-trunk to seven or eight times its length 
(according to the species), we begin to get a rough 
idea of the general anatomy oi a _ Sea-spider ; 
all excepting its head and its egg-carrying legs ; 
although it should be mentioned that two 
Antarctic genera are made still more extra- 
ordinary (and unspider-like) by possessing. five 
pairs of legs. 
The head is a short column terminating in a 
proboscis, which may be either much shorter or 
much longer than the whole body, including the 
leg segments and the abdomen proper. Attached 
to the sides of the proboscis are a pair of pincer- 
Photo oy] [Hugh Main, PBS. like organs, often armed with teeth, and a pair of 
SEA-SPIDERS. ee é eae ; 
spinous, jointed palps, or feelers ; the latter organs, 
Two fine specimens magnified about three times. . 
Notice the large head, the huge body-joints to which the however, are absent in some adult forms. Also 
limbs are attached, and the minute body proper. 
there are four simple eyes arranged in two pairs, 
these being the only special sense-organs known in these creatures. 
Finally, just below the head, and attached to the under-side, are a pair of egg-carrying legs. It 
is in the males that the latter organs are most developed, the care of the eggs being their special 
occupation. The females of some species are provided with these legs, but only in one species are 
they known to carry the eggs ; in several genera they are quite absent in the females. 
It is obvious, then, that Sea-spiders are extremely queer animals, and consequently the zoologist, 
in classifying them, is compelled to provide them with a special place in a group which he designates 
the Pycnogons. Their anatomy seems to reveal characters of some of the highest members of the 
spider family combined with some very degenerate features, and both made still more complex by 
comparatively recent specialization of many parts. 
