. The Australian Museum magazine. Natural history. THE AUSTRALIAN MUSEUM MAGAZINE. Ill LIMPETS. The limpets are proverbial for stick- ing to the rocks, and, as a matter of fact, no amount of ordinary pulling in a straight line will remove one from its holding. The central part of the foot is raised from the rock by muscular ac- tion, forming a kind of sucker with a partial vacuum between the foot and the rock, and, since the edges of the foot tit the support perfectly, the ex- ternal atmospheric pressure helps the animal to resist being detached. The limpets are always easily known by their do
. The Australian Museum magazine. Natural history. THE AUSTRALIAN MUSEUM MAGAZINE. Ill LIMPETS. The limpets are proverbial for stick- ing to the rocks, and, as a matter of fact, no amount of ordinary pulling in a straight line will remove one from its holding. The central part of the foot is raised from the rock by muscular ac- tion, forming a kind of sucker with a partial vacuum between the foot and the rock, and, since the edges of the foot tit the support perfectly, the ex- ternal atmospheric pressure helps the animal to resist being detached. The limpets are always easily known by their dome-shaped or tent-shaped shells, a shape on which the battering waves can get no purchase to dislodge them. The limpet, which also has a ribbon tongue, is a vegetarian and feeds on the green sea growths on the rocks. A re- markable thing about these animals is their homing instinct. A limpet hol- lows out a depression in a rock to ac- commodate itself nicely, and, though it leaves this at feeding time in search of food, it will return again and again to its old home, and never seems to settle in the wrong hollow by mistake. CHITONS. Occasionally gliding over the rock, but more often as still as the stone itself. may be seen those curious molluscs, the chitons, often called mail-shells. Instead of one solid shell like a limpet, these animals have developed a hard calcareous armour composed of eight separate trans- verse pieces, which fit one over tlie other something after the manner of tiles on a roof. You can see this well if you detach a chiton from its rock and place it on its back, when it will proceed to roll itself up into a ball with the shell on the outside. A leathery band or girdle runs around the outside of the eight plates. The chitons have no eyes or tentacles, whereas the periwinkles and their kind, have two tentacles and also eyes on very short stalks, at the base of the tentacles. The chitons are vegetable feeders, liv- ing on minute seaweeds and those very tiny
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectnaturalhistory, booky
