Nematocyst

A nematocyst is a specialized cell found in Cnidaria, a phylum that includes creatures such as jellyfish, coral, and sea anemones. Nematocysts are a key feature of the cnidarians, serving as their primary means of prey capture and defense. Each nematocyst comprises a small capsule containing a tightly coiled thread or tubule. When triggered by physical or chemical stimuli, the nematocyst discharges, rapidly uncoiling the tubule, which can inject toxins into the prey or predator.

The mechanism of nematocyst discharge is one of the fastest biological processes known, occurring within microseconds. The force of the discharge is powerful enough to penetrate the exoskeletons of crustaceans and the skin of humans. The toxins delivered by some species' nematocysts can cause serious harm to humans, ranging from painful stings to, in extreme cases, death.

Nematocysts are produced by cnidocytes, specialized cells unique to cnidarians. Cnidocytes develop from interstitial cells, which migrate to the tentacles and body surface where they differentiate into cnidocytes. Each cnidocyte develops a single nematocyst. The diversity of nematocysts within and among cnidarian species is vast, with differences in size, shape, and function reflecting adaptations to a wide range of ecological niches.

The study of nematocysts and cnidocytes has implications beyond understanding cnidarian biology. Research into the biochemistry of nematocyst toxins has potential applications in medicine, including the development of new drugs and treatments for medical conditions. Additionally, understanding the mechanisms of nematocyst discharge and the properties of the toxins can contribute to the development of better treatments for jellyfish stings and insights into the evolution of venom systems across different species.