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"Did it sting?" "No. You wouldn't find jelly-fishes in a hole like that. It felt like a tremendously great polly-squiggle with a big parrot's beak, and my hand nearly went in." "Get out!" said Bob, "there are no big ones." "How do you know?" retorted Bigley. "That felt just like a large one." "Did he take hold of you with his suckers?" I said. "No, I didn't give him time."
The internal cavity and the radiating tubes, instead of being connected with the outer wall of the body as in Polyps, or hollowed out of the substance of the body as in Jelly-Fishes, are here inclosed within independent walls of their own, quite distinct from the wall of the body.
Leuckart proposed to subdivide the Radiates into two groups: the Coelenterata, including Polyps and Acalephs or Jelly-Fishes, and Echinoderms, including Star-Fishes, Sea-Urchins, and Holothurians.
To very few does this term recall either the large Discophore, with its purple disk and its long streamers floating perhaps twenty or thirty feet behind it as it swims, or the Ctenophore, with its more delicate, transparent structure, and almost invisible fringes in parallel rows upon the body, which decompose the rays of light as the creature moves through the water, so that hues of ruby-red and emerald-green, blue, purple, yellow, all the colors of the rainbow, ripple constantly over its surface when it is in motion, or the Hydroid, with its little shrub-like communities living in tide-pools, establishing themselves on rocks, shells, or sea-weeds, and giving birth not only to animals attached to submarine bodies, like themselves, but also to free Medusae or Jelly-Fishes that in their turn give birth again to eggs which return to the parent-form, and thus, by alternate generations, maintain two distinct patterns of animal life within one cycle of growth.
His reason for this distinction is the fact that in the latter the organs are inclosed within walls of their own, distinct from the body-wall; whereas in the former the organs are formed by internal folds of the outer wall of the body, as in the Polyps, or are hollowed out of the substance of the body, as in Jelly-Fishes.
Backbones are called by the Wise Men vertebrae; animals that have backbones are named Vertebrates; and animals that lack backbones are named Invertebrates." "Tell us the names of some Invertebrates, please, Doctor," said Rap. "Well, all sorts of insects are Invertebrates, and so are lobsters and crabs, oysters and clams, worms, starfishes, jelly-fishes, corals, and even sponges.
The jelly-fishes of another section are furnished with one or more air-bags, which assist them in swimming, and hence bear the name of hydrostatic acalephæ. From the top of it rises a purple crest, which acts as a sail, and by its aid the little voyager scuds gaily before the wind.
From those fertilised eggs grow young polyps, which fix themselves to rocks or weeds, and grow up to bud and multiply by fission, and eventually to produce again by fission a generation of jelly-fishes!
They have to traverse the surface of the ocean amidst all diversities of weather. Paddles alone would not suffice for them. They must be enabled to take advantage of the winds. Sails, therefore, are added, and the mightiest agents in nature are commissioned to speed the little voyagers on their way. We have already mentioned that some of the jelly-fishes possess the power of stinging.
But this element of consciousness is one which it is exceedingly difficult to detect in our analysis, and yet upon it our classification and the psychic position of an animal must to a great extent depend. The amoeba contracts when pricked, jelly-fishes swim toward the light, the earthworm, "alarmed" by the tread of your foot, withdraws into its hole.
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