The largest predator in the Arctic would be a starfish

In a new study published in PNAS, and reported in Focus, Rémi Amiraux of the University of Manitoba, Canada, said the Arctic's biggest predator would be a starfish

by Lorenzo Ciotti
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The largest predator in the Arctic would be a starfish

In a new study published in PNAS, and reported in Focus, Rémi Amiraux of the University of Manitoba, Canada, said the Arctic's biggest predator would be a starfish. There is more than one food chain in any ecosystem, and often a single species can be part of more than one chain.

This interweaving forms what is called a food web, which is a summary of how organic matter moves within the ecosystem. As reported on Focus, the Arctic food web has always seen the polar bear at the top, but according to Amiraux this primacy is a bias.

The Canadian team then reconstructed the trophic web of the waters around Southampton Island by taking all species into consideration for the first time, and not just those in the open sea.

The largest predator in the Arctic would be a starfish

Pterasteridae, starfish, are found at the top of all food chains of which they are a part.

They feed on bivalves, sea cucumbers, and sponges, all groups that are themselves predators on something else, and have no predators themselves. Their position in the Arctic food web is identical to that of polar bears, and like them these starfish feed not only on live prey but also on corpses.

The only difference is in the size of their meals, which has so far led us to focus only on the bears and not enough on the stars. Pterasterids are primarily deep-water, and have an inflated aboral surface. Like many other members of the ordo Velatida, they have a hole in the middle of the central disc called osculum, from which they can expel mucus for defending against predators.

Many species brood their young in an internal chamber flushed with seawater. Fossil pterasterids have been found as early as the upper Campanian of the Cretaceous period. Starfish are present in all the seas of the world and the most conspicuous are found in the tropical ones.

Most starfish typically have five rays, or arms, that branch off from a central disk. Many species frequently have six or more rays.