Cnidocitos

Cnidocitos are specialized stinging cells found in cnidarians, a phylum of aquatic invertebrates that includes jellyfish, corals, sea anemones, and hydras. These cells are unique to this group of animals and play a crucial role in their feeding, defense, and locomotion.

Each cnidocito contains a cnida, which is a capsule filled with a coiled, barbed, or sticky thread. This thread, also called a nematocyst when it's a stinging organelle, is discharged explosively when triggered by external stimuli such as touch or chemical cues. The rapid expulsion of the thread can inject venom into prey or predators, immobilizing them or causing irritation.

The structure and function of cnidocitos vary among different cnidarian species. Some cnidocitos are designed to pierce and inject venom, while others are used for adhesion or entanglement. The process of cnidocito discharge is a complex biomechanical event, involving a rapid increase in osmotic pressure within the capsule, which forces the thread outward with considerable speed and force.

Cnidarians are able to continuously produce and replenish cnidocitos throughout their lives. The development and differentiation of these cells occur in specialized regions of the animal's body, often associated with tentacles or feeding structures. The presence of cnidocitos is a defining characteristic of the phylum Cnidaria, setting them apart from other animal groups. Understanding cnidocitos is key to comprehending the biology and ecological interactions of these fascinating marine organisms.