Fig. 50.—Sea Anemone.
The Sea Anemone, like the coral polyp, lives in the sea, but like the fresh-water hydra, it deposits no limy support for its body. The anemone is much larger than the hydra and most coral polyps, many species attaining a height of several inches. It does not form colonies. When its arms are drawn in, it looks like a large knob of shiny but opaque jelly. Polyps used to be called zoophytes (plant-animals), because of their flower-like appearance (Figs. [50], [51]).
Fig. 51.—Sea Anemones.
CHAPTER V
ECHINODERMS (SPINY ANIMALS)
The Starfish
Fig. 52.—Starfish on a rocky shore.
Suggestions. Since the echinoderms are aberrant though interesting forms not in the regular line of development of animals, this chapter may be omitted if it is desired to shorten the course.—The common starfish occurs along the Atlantic coast. It is captured by wading along the shore when the tide is out. It is killed by immersion in warm, fresh water. Specimens are usually preserved in 4 per cent formalin. Dried starfish and sea urchins are also useful. A living starfish kept in a pail of salt water will be instructive.