What is stinging cells of the hydra?

Stinging cells, also known as nematocysts, are specialized structures found in the tentacles of hydra and other cnidarians, such as jellyfish and sea anemones. These cells serve as a defensive mechanism and are used for capturing prey. Here is an overview of stinging cells in hydra:

Structure:

- Stinging cells consist of a small, oval-shaped capsule containing a coiled, thread-like structure called the nematocyst thread or tubule.

- The capsule has an operculum, a small lid or trapdoor at one end, which remains closed until triggered.

- The nematocyst thread is barbed and can be rapidly ejected from the capsule upon contact with specific stimuli.

Mechanism of Action:

- When the hydra comes into contact with potential prey or a threat, the mechanoreceptors on the surface of the tentacles detect the stimulus.

- This triggers the discharge of stinging cells. The operculum of the capsule opens, and the nematocyst thread is rapidly everted and shoots out with great force.

- The barbed thread penetrates the skin or exoskeleton of the prey, injecting toxins or venom.

- The toxin paralyzes and subdues the prey, making it easier for the hydra to capture and ingest it.

Types of Stinging Cells:

There are different types of stinging cells found in hydra, each serving specific functions:

- Penetrants: These are the most common type and are used for capturing and paralyzing prey.

- Volvents: These cells wrap around and entangle the prey, preventing it from escaping.

- Glutinants: These cells produce a sticky substance that helps to attach the hydra to surfaces or immobilize the prey.

The presence of stinging cells is a key characteristic of cnidarians and plays a crucial role in their survival. By utilizing these specialized structures, hydra and other cnidarians can effectively capture and subdue their prey in their aquatic environments.