Tank No. 1. 
31 
with their sucker-feet and brought to their mouth. Their food consists 
chiefly of shellfish, but often they will capture fishes and crabs. They 
are one of the most formidable enemies of fishery, and in its interest 
they should be systematically destroyed. 
Like some of the Sea-urchins, most Sea-cucumbers live by swal¬ 
lowing sand and mud and digesting the adhering organic particles. Some 
(e. g. Cueumaria, Fig. 41) manage matters very differently. They remain 
motionless on a stone or other prominent object, stretching out their large 
branching tentacles and 
carrying them one after 
the otherinto their mouth, 
sucking off the small 
animals which in the 
meantime have settled 
upon them. With a little 
patience this proceeding 
may be easily observed. 
—Some Sea-urchins (e.g. 
Dorocidaris, Fig. 42) 
have very long spines; 
in these cases, however, 
the sucker-feet can be extended to a great length, for they must always 
reach beyond the spines. In many cases we find between the spines 
special moveable stalks bearing small pincers, which can also seize small 
objects. — The Starfishes have 
their eyes at the extremities of 
their arms. They can, however, 
probably not see very distinctly, 
but only distinguish between light 
and darkness. 
The Echinoderms are divided 
into four large groups : 
1. The Feather-stars (Cri- 
noidea), 2. the Sea-stars (Aste- 
roidea), 3. the Sea-urchins (Echi- 
noidea) , 4. the Sea-cucumbers 
Holothurioidea). 
Of the Feather-stars the 
Aquarium contains Antedon ro¬ 
sacea (Fig. 40) in straw-coloured, orange-coloured, blood-red, or spotted 
brown and white varieties. Generally they hold on to coral-branches, so 
as to appear like flowers, growing on submarine trees. 
The Sea-stars are divided into the Starfishes or Asterids, and the 
Brittle-stars or Ophiurids. The Starfishes are represented in the Aquarium 
by the genera Luidia (Fig. 43), Astropeeten (Fig. 37), Asterias (Fig. 44), 
Echinaster (Fig. 38), Palmipes, and others; the Brittle-stars by Ophio- 
derma (Fig. 45) and others. 
The Sea-urchins are very conspicuous; Echinus acutus especially on 
account of its considerable size. The large yellow ovaries (roe) of 
Fig. 42. Dorocidaris papillata j ife nat. size. 
The sucker-feet are not visible. 
Fig. 41. Cueumaria cucumis, on a stone, with out¬ 
stretched tentacles, */2 nat. size. 
