Stachelzellen

Stachelzellen, also known as cnidocytes, are specialized cells found in cnidarians, a phylum of aquatic animals that includes jellyfish, corals, sea anemones, and hydras. These cells are a defining characteristic of the phylum and are primarily used for prey capture and defense.

Each stachelzelle contains a unique organelle called a cnida, which is essentially a coiled, barbed or stinging thread or a sticky filament. The most common and well-known type of cnida is the nematocyst, which functions as a harpoon. When triggered by physical or chemical stimuli, the nematocyst rapidly everts, firing its barbed thread outwards. This thread can inject venom, entangle prey, or adhere to surfaces.

The precise mechanism of cnida discharge is rapid and complex, involving a sudden increase in osmotic pressure within the cnida capsule, causing it to explode outwards. Different types of cnidarians possess various types of cnidae with specialized functions, though all are designed for rapid deployment.

Stachelzellen are typically found in clusters on the tentacles and body surfaces of cnidarians. The venom injected by some nematocysts can be potent, paralyzing or killing prey, and in some cases, causing significant harm to humans. However, the sting of many cnidarians is mild and may only cause irritation. The presence and potency of stachelzellen are crucial for the survival and ecological success of cnidarians in their aquatic environments.