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Show Jet Propulsion Isn't New ; Fish Have Long Used It Jet propulsion isn't as new as we think. There are about 270-species 270-species of fish, including cuttlefish which move through the water and very quickly by expelling jets of water from their gill slits,. ' which are placed in just the right position to make full use of this? form of power. Tail and fins are quite motionless in this method of submarine kravel. If jet-prdpulsion fish finds it is traveling in wrong direction, it simply puts on emergency brakes by sucking in water through gill slits and expelling it from mouth. |