Snakelocks anemone (Anemonia viridis). Anemones have an array of tentacles which act as a defence mechanism and a means of capturing plankton. When the tentacles are triggered they release a poison into the predator or prey. The snakelocks anemone cannot retract its tentacles whilst out of the water so they tend to occupy the low tidal reaches of the shore. The majority of anemones inhabit tropical reefs although some like the snakelock anemone have evolved to inhabit cold-water environments.