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J. Perelman
"Entertaining physics". Book 2.
Chapter 1. The basic laws of mechanics


You will be weird to hear that there are many living beings, for which the imaginary "raising himself by the hair" is the usual way they move in the water.

The swimming motion cuttlefish.

Cuttlefish and generally most cephalopods move in the water thus: take water in the Gill cavity through the side slit and a special funnel in front of the body, and then vigorously throw a jet of water through the mentioned funnel; however, they - according to the law of counter - receive feedback stimulus, sufficient to quickly swim back side of the body forward. Cuttlefish can, however, guide tube funnel sideways or backwards and rapidly squeezing the water from it, move in any direction.

Based on the same and the movement of the Medusa: the contraction of muscles she pushes out of its bell-shaped body of water, receiving the impetus in the opposite direction. A similar technique is used when the movement salpy, larvae of dragonflies and other aquatic animals. And we were in doubt if it is possible to move!

Entertaining physics J. Perelman


System Orphus


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