Half hours with the lower animals : $b protozoans, sponges, corals, shells, insects, and crustaceansHolder, Charles Frederick
Science
Half hours with the lower animals : $b protozoans, sponges, corals, shells, insects, and crustaceans
Holder, Charles Frederick
Animals; Invertebrates
The crinoids resemble lilies so closely that they are called stone
lilies. They are animals, however, related to the starfishes. They
have a long stem, with rootlike branches to support it, and are capped
with what appears like an inverted starfish, and is literally a
starfish perched upon a stem. Fossil crinoids have long been known,
and beautiful specimens may be seen in all our museums, but the fact
that they still live upon the globe is a modern discovery. It is said
that Agassiz stated that he expected to find them alive off the coast
of Cuba, and when a deep locality was dredged, up came the living
crinoids, or forms almost identical with them. Since then they have
been dredged in great numbers by all the great deep-sea explorers. Some
have long stems, some short. On one, the Comatula, when it is full
grown, the crinoid leaves its stalk, and lives a free, roving life
after the fashion of many starfishes.
The crinoid, with its long slender stem, its branching tendrils, its
flowerlike top, is one of the most graceful of all animals, as might
be imagined from the drawing. Examine the crinoid as closely as one
may, it still resembles a stone lily, and only its slow movements,
contracting and folding, suggest life. Nevertheless, it is a very
complicated animal. It consists of a central body, protected by
numerous plates, as seen in Figure 46. From the edges extend five, or
often more, branches or arms, and from them in turn branch other arms,
so that the top resembles a feather or brush, from which they are
called feather stars. In the center of the stars is a mouth, food being
caught by the many branching tentacles. The history of the development
of crinoids is very interesting. They pass through several curious
stages in the course of growth from infancy to old age, and some of
the shapes are so curious that no one, not familiar with them, would
suspect that here was a growing crinoid.
VII. THE STARS OF THE SEA
[Illustration: FIG. 47.--Basket starfish.]
[Illustration: FIG. 48.--Lower surface of starfish (_Goniaster_),
showing suckerlike feet; a slow mover.]
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