Page:Picturesque Dunedin.djvu/108

96 Close to this is another skeleton formed of long strips of silica—the glass-rope. One end of the bundle is the resting-place of the organism whose skeleton it is, while the other is embedded in the mud at the bottom of the sea; but the Japanese used to fix it in a piece of rock and affirm that the glass-rope grew there, reminding one forcibly of the story which declared that the birds of paradise were destitute of legs. These organisms are sponges, which name, however, is apt to convey to the uninformed an erroneous impression. The ordinary bath-sponge, for instance, is simply the calcareous skeleton of a colony of animals called sponges, from which all the soft parts have disappeared, and the fact is often forgotten that it was formerly a portion of a living animal. There are spirit specimens of sponges, with the soft parts preserved, and it is interesting to-notice the great difference in appearance between these and the simple skeletons sold in shops.

Many of the sponges picked up on the beaches about Dunedin, are hard and not at all elastic. This is owing to their skeletons being composed of a horny substance containing silica, and, consequently, they are unfit for ordinary use.

Next come the jelly-fish, which, besides their attractive appearance, are noteworthy, in being about the first organisms in the animal kingdom, which have nerves by which to regulate their movements. Experiments have been performed, which show conclusively, that the muscular contractions of the swimming-bell by which the jelly-fish is propelled are due to nerves, for when these nerves, or the structures said to be such, are cut away, the animal is totally unable to originate or direct its movements. Jelly-fish also possess the rudiments of eyes and ears.

Closely allied to the jelly-fish is the Portuguese man-of-war, found occasionally on the sea-shore about Dunedin. Underneath its large hollow float are very numerous tentacles, of all colours, and capable of inflicting a sharp sting on anyone who inadvertently comes in contact with them. Owing to the perishable nature of this animal and the jelly-fish, which are chiefly water, they are represented in the museum by models and spirit specimens only.