stichocyst

A stichocyst is a specialized cell found in the cnidocytes (stinging cells) of cnidarians, a group of aquatic animals that includes jellyfish, sea anemones, and corals. These cells are responsible for the stinging or venomous properties of cnidarians. The term "stichocyst" comes from the Greek words "stichos," meaning "sting," and "kystis," meaning "bladder."

Stichocysts are typically located in the tentacles of cnidarians and are used for defense and predation. When triggered, the stichocyst releases a harpoon-like structure called a nematocyst, which is barbed and filled with venom. This venom can cause pain, paralysis, or even death in prey or predators. The nematocyst is propelled by the contraction of the stichocyst's cytoplasm, which acts like a spring.

The structure of a stichocyst consists of a basal body, a capsule, and a nematocyst. The basal body is the part of the cell that remains after the nematocyst has been discharged. The capsule is a membrane that surrounds the nematocyst and helps to protect it. The nematocyst itself is a complex structure that includes a filament, a barb, and a venom-filled capsule.

Stichocysts are a fascinating example of how simple cells can evolve to perform complex functions. They are also an important tool for studying cell biology and the evolution of multicellular organisms.