#actiniidae

A fish-eating anemone (Urticina piscivora) in Monterey Bay National Marine Sanctuary, California, USA

Siblings can be a pain-- especially when they're all clones of you. The aggregating anemone is often found in masses of up to a hundred polyps, all of them identical to each other. The ones on the edge of the mass are smaller and unable to reproduce, but have larger, specialized tentacles called acrorhagi that they use to defend their territory from invading anemone masses.

(Image: A small group of aggregating anemones (Anthopleura elegantissima), one of which is in the middle of dividing, by Dave Cowles)

In Māori Humenga or Kōtore Ōriwa.

A common sea anemone in New Zealand and Southern Australia, favouring gravel-filled cracks between boulders and in rockpools, or buried in sand. May be olive to emerald green.

The colour is probably related to the symbiotic photosynthetic algae (zooxanthellae) they contain, like tropical corals. If kept slightly starved zoothanthellae produce sugars the polyp can digest, but the anemones also contain chemicals such as Phaeophytin, anthocyans, β-carotene and carotenoid pigments that are very likely produced by the alga, and may protect the animal from UV light.

Starburst anemone (Anthopleura sola)