Stiffened shaft

Figure 18.12 The morphology of nematocysts (stinging cells). (Photo: L. Gershwin.)

Nematocysts, the weapons of jellyfish, are basically a capsule with a spring-loaded thread coiled up inside, and an external hair-trigger at one end. The thread has rows of spines near the base, and usually a relatively smooth shaft along the rest of its length. When the hair trigger is activated, the thread is discharged inside-out (i.e. spines first), with tremendous force, about 40 000 times the force of gravity. Nematocysts can easily penetrate crab carapaces, fish scales, and human skin, so delivering their subcutaneous dose of venom. Nemato-cysts discharge following a combination of mechanical and chemical stimulation.

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Worm Farming

Worm Farming

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