Stinging Cells

Definition

Stinging cells, also known as cnidocytes, are specialized cells found in cnidarians that contain a unique organelle called a nematocyst. These cells are essential for the defense and feeding mechanisms of organisms like jellyfish, corals, and sea anemones. When triggered, nematocysts discharge a harpoon-like structure that can inject toxins into predators or prey, serving both as a means of capturing food and as a defense against threats.

5 Must Know Facts For Your Next Test

1. Stinging cells are primarily located on the tentacles and body surfaces of cnidarians, making them crucial for interactions with their environment.
2. Nematocysts can vary in type, with some designed to entangle prey and others specifically adapted to deliver venom.
3. The discharge of nematocysts is a rapid process that can occur within milliseconds, allowing cnidarians to react quickly to threats or opportunities.
4. While some stinging cells can cause mild irritation to humans, others, like those from certain jellyfish species, can be extremely dangerous and even lethal.
5. Cnidarians rely heavily on their stinging cells for survival; they use them to capture prey such as small fish and plankton, as well as to deter predators.

Review Questions

• How do stinging cells function in the feeding behavior of jellyfish?
  • Stinging cells in jellyfish play a vital role in their feeding behavior by allowing them to capture prey efficiently. When jellyfish encounter potential food, such as small fish or zooplankton, the nematocysts in their stinging cells discharge upon contact. This releases toxins that paralyze the prey, making it easier for the jellyfish to bring it to their mouth for consumption.
• Discuss the ecological significance of stinging cells in coral reefs.
  • Stinging cells are ecologically significant in coral reefs as they help corals capture zooplankton and other small organisms for nourishment. This feeding mechanism supports the growth and health of corals, which are crucial components of reef ecosystems. Additionally, the presence of stinging cells deters herbivores from consuming coral polyps, contributing to coral survival and biodiversity within reef habitats.
• Evaluate the impact of stinging cell adaptations on the survival strategies of sea anemones in their environments.
  • The adaptations of stinging cells in sea anemones significantly enhance their survival strategies by providing effective means for both predation and defense. By utilizing nematocysts to inject toxins into potential prey, sea anemones can secure necessary nutrients from small fish and crustaceans. Simultaneously, these stinging cells act as a deterrent against larger predators. This dual functionality not only ensures their survival but also positions them as active participants in their ecosystem, influencing population dynamics within their habitat.

Related terms

Nematocyst: A specialized organelle within stinging cells that contains a coiled thread capable of injecting toxins into other organisms.

Cnidarian: A phylum of aquatic animals that includes jellyfish, corals, and sea anemones, characterized by the presence of stinging cells.

Polyp:

A sessile form of cnidarians that typically resembles a cylindrical body with tentacles at one end and is attached to a substrate.