Sea anemone
Sea anemone
From Wikipedia, the free encyclopedia
Sea anemones are a group of water dwelling, predatory animals of the order Actiniaria; they are named after the anemone, a terrestrial flower. As cnidarians, sea anemones are closely related to corals, jellyfish, tube-dwelling anemones, and Hydra.
Anatomy
A sea anemone is a small sac, attached at the bottom to the surface beneath it by an adhesive foot, called a basal disk, with a column shaped body ending in an oral disk. The mouth is in the middle of the oral disk, surrounded by tentacles armed with many cnidocytes, which are cells that function as a defense and as a means to capture prey. Cnidocytes contain cnidae, capsule-like organelles capable of everting, giving phylum Cnidaria its name.[1] The cnidae that sting are called nematocysts. Each nematocyst contains a small vesicle filled with toxins—actinoporins—an inner filament and an external sensory hair. When the hair is touched, it mechanically triggers the cell explosion, a harpoon-like structure which attaches to organisms that trigger it, and injects a dose of poison in the flesh of the aggressor or prey. This gives the anemone its characteristic sticky feeling, noted upon touching.
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