What is the cnida?
Q: What is the cnida?
A: The cnida is the basic term for the stinging apparatus of the phylum Cnidaria. It enables the animals to catch their prey and is present in all cnidarians.
Q: What are some variations of cnidae?
A: There are three main types of cnidae: nematocysts, ptychocysts, and spirocysts, with many variations. Depending on the species, one or more types may be on the organism.
Q: How does a nematocyst work?
A: A nematocyst is a harpoon-like structure which holds and paralyses small prey. It contains an organelle with a hollow, coiled, thread-like structure and has a hair-like trigger on its outside. When triggered by touch, it fires like a harpoon into its target and injects neurotoxins that paralyze it.
Q: What type of cnidae do Anthozoa possess?
A: Anthozoa possess mainly nematocysts as their type of cnidae.
Q: How quickly does a nematocyst fire?
A: Nematocysts fire in no more than a few microseconds after being triggered by touch.
Q: What cell produces the cnida?
A: The cell which produces the cnida is variously called a cnidocyte, cnidoblast, or nematocyte and is highly specialised for just one function - producing and firing off the stinging apparatus when triggered by touch.
