The More Sea Anemones Eat, the More Tentacles They Grow

Sea anemones are the first species to turn food into extra limbs.
Fabienne Lang
Sea anemones growing legsAnniek Stokkermans/EMBL

A simple starlet sea anemone has become the prime focus of a group of international researchers as it's defying the laws of genetics. 

The more it eats, the more tentacles it grows. Given the lifespan of a certain species of sea anemone can live over 65 years, that's quite a few tentacles sprouting out from the originally-small sea creature. 

The study was led by EMBL Heidelberg researchers, and published in Nature Communications in early September.


An anemone that just keeps growing

Your genetic code is made in such a way that you grow two legs and two arms, like all mammals. It's the same for fish and their fins, and insects and their wings and legs. 

So it's come as an interesting discovery that sea anemones don't develop in quite the same manner, genetically speaking. They have variable tentacles, as per the research.

Until now, it was always unclear what regulated the number of tentacles a sea anemone would grow. It appears that they grow tentacles by eating, much like trees grow branches, as lead researcher Aissam Ikmi pointed out. "Controlling the number of tentacle arms by food intake makes the sea anemone behave more like a plant developing new branches than an animal growing a new limb," he explained.

It's an interesting find given some sea anemone species live over 65 years, meaning they can just keep growing and growing the number of tentacles they have. It marks a fascinating evolution example. "As predominantly sessile animals, sea anemones must have evolved strategies to deal with environmental changes to sustain such a long lifespan," as Ikmi indicated.

The scientists noted that the growth of sea anemone tentacles happens throughout its life, from its youth until its fully grown, although it uses different ways to grow them depending on which stage of its life it's in. It comes in handy when a tentacle is damaged, as it simply grows one back!

There are certainly some fascinating sea creatures out there, and it's incredible just how much we're still discovering about them.

The team observed more than 1,000 sea anemones to reach its conclusion, and now the researchers will look into the nutrients the creatures need in order to grow their tentacles.

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