Critter of the Week: Sea Anemone

11 July 2017

Interview with 

Sarah Lane, Plymouth University

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In this week's Critter of the Week - a special version of Question of the Week for Marine Month - Georgia Mills has been treading carefully around the sea anemone...

Georgia - Name: Sea anemone. Phylum: Cnidaria. Location: sea anemones are common in tropical reefs, but they're found in every ocean in the world. Special abilities: expert harpooning and clone warfare.

Sarah Lane from Plymouth University makes the case for this contender for Critter of the Week...

Sarah - If you’ve ever been down to the sea while the tide is out, you may have noticed what appear to be little blobs of strawberry jam, covering the surfaces of exposed reefs. These blobs may appear ugly and uninteresting, but when the tide comes in, rings of vibrantly coloured tentacles appears and they are transformed into sea anemones – known for their beauty as the flowers and jewels of the sea.

Georgia - Indeed! Sea anemones even take their name from a flower but plants, they are most certainly not.

Sarah - Anemones are related to jelly fish using stinging tentacles to zap anything edible that comes past. They live in a variety of habitats from the intertidal zone down to offshore reefs, and even into the lightless abyss, and can be anywhere from millimetres to metres in diameter. Unlike their buoyant cousins, anemones are generally harmless to humans and spend most of their lives attached to rocks. But don’t let their seemingly sedentary lifestyle fool you. Anemone’s lives are far from tame. Despite having no central nervous system, sea anemones possess weapons – bead-like structures, chockfull of stinging harpoons which frame the edge of their bodies – their sole purpose, to keep other anemones away. Anemones use these harpoons when faced with a nosy neighbour, covering their opponent in flesh-eating stings in an effort to make them retreat.

Georgia - Flesh-eating harpoons, lovely! But if you think just one sounds like a handful…

Sarah - Some species of anemones even form huge colonies which act like a single army. Some of the anemones act as scouts surveying the perimeter for intruders while other, more heavily armed individuals; take the role of warriors, awaiting the scout’s signal. When two colonies meet, a no man’s land forms between them. If any anemone crosses this line, the bloodshed begins and warrior cover invaders with swades of stinging harpoons until the white flag is raised, and the other colony retreats.

Georgia - So, these are the roman army of the war to world. But as teams go, these guys take keeping it in the family to a whole new level.

Sarah - These colonies work together as one. In fact genetically, they are one. As well as possessing gnarly weapons, anemones can reproduce asexually. Meaning, that their offspring are clones and they can form entire armies of mini me-s with which to defend their home, pretty cool for a blob of jam.

Georgia - So there's much more to sea anemones than providing a home for Nemo and having a difficult name to say. Name: Sea anemone, see an enemy, sea anomany… between their flesh-eating harpoons and their vicious clone wars; they’ve won their way to Critter of the Week.

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