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In the case of certain plants and animals, cell-groups grow together into a so-called "bud," which later detaches itself from the parent body and forms a new individual living organism, as in the case of the polyps or the tubers in plant life. A tree, for instance, may be grown from a graft which has been cut off and planted in the ground.
The lower portion of it is fixed in the muddy bottom of the sea, but the upper portion is free, and gives off a number of branches, on which the individual polyps are seated. The whole colony thus has the appearance of a highly ornamental pen. There is one British species, Pennatula phosphorea, which is found in tolerably deep water, and is from two to four inches in length.
The material used by the polyps in building the coral is chiefly lime, which they have the power of gathering out of the water, and the fine coral-powder, sinking to the bottom, makes large quantities of hard limestone. Soft chalk is rarely, if ever, found near the coral islands.
Reaumur transferred this name to the newcomers, and called them fresh-water polyps, to the infinite amusement of Voltaire, who had declared that they were only blades of grass; a new proof, among many others, that in natural history all the intellect in the world is not worth a pair of good eyes.
All agree that this was very many thousand years ago. Agassiz tells us that the same species of polyps which are now building coral walls around the present peninsula of Florida actually made that peninsula, and have been building there for centuries which must be reckoned by thousands.
One may ask how the narrow radiating tubes of the Acalephs, traversing the gelatinous mass of the body, can be compared to the wide radiating chambers of the Polyp; and yet nothing is more simple than to thicken the partitions in the Polyps so much as to narrow the chambers between them, till they form narrow alleys instead of wide spaces, and then we have the tubes of the Jelly-Fish.
In the lowest class of this division of the Animal Kingdom there is a group so similar to the Polyps, that, until recently, they have been associated with them, the Bryozoa.
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.
Among other specimens from these waterways, our nets brought up some peacock-tailed flabellarian coral, polyps flattened into stylish shapes and unique to this part of the ocean. The Nautilus kept to its southeasterly heading. On December 1 it cut the equator at longitude 142 degrees, and on the 4th of the same month, after a quick crossing marked by no incident, we raised the Marquesas Islands.
Some of the polyps live on tiny animals with a lot of flint in their shells and the skeleton gets like glass. They call them glass sponges. Conditions have got to be just right for their development, they're a most particular sort of creature." "But how do they feed?"
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