Actinia
Actinia is a genus of sea anemones, commonly known as “sea anemones” or “actinians.” These solitary polyps are characterized by their cylindrical body with a single opening that serves as both mouth and anus, surrounded by tentacles. They are members of the phylum Cnidaria, class Anthozoa, and order Actiniaria. Actinia species are found worldwide in a variety of marine habitats, from intertidal zones to deeper waters.
Common Names
Common names for Actinia species include:
- Sea anemone
- Actinian
- Beadlet anemone (Actinia equina)
Characteristics
Actinia anemones are characterized by the following features:
- Solitary polyps: They live as individual organisms, unlike colonial corals.
- Cylindrical body: Their body is typically cylindrical with a single opening, the mouth, surrounded by tentacles.
- Tentacles: The tentacles are arranged in whorls around the mouth and contain stinging cells called nematocysts, used for defense and capturing prey.
- Muscular foot: They have a muscular foot, called a pedal disc, that allows them to attach to rocks, shells, or other surfaces.
- Color variation: Actinia species come in a variety of colors, including red, orange, green, and brown.
Environments
Actinia species are found in a wide range of marine environments, including:
- Intertidal zones: They are commonly found on rocky shores, exposed to the tides.
- Shallow waters: They can also be found in shallow, sheltered waters.
- Deeper waters: Some species can tolerate deeper waters.
References
For more information on Actinia, refer to these reliable sources: