Like crabs, starfish are rockpool royalty – they’re the creatures families most want to find when they explore the coast on holiday.
The orange, five-armed species usually encountered in Britain and Ireland is the common starfish, which as its name implies, is widespread, though only on the lowest parts of the shore.
In common with all starfish, it has neither a brain nor blood. Instead, it draws in sea water to transport food and oxygen around its body.
It’s also rather slow-moving, but is nevertheless a formidable predator of bivalve molluscs such as mussels.
When a common starfish attacks a mussel, it wraps its arms around the victim, grips tight with its thousands of tiny tube feet and pulls hard to prise the paired shells open.
Next, the five-armed creature forces one of its stomachs (it has two!) out of its mouth and into the gap between the shells to digest the mussel, before pulling its stomach back inside itself. This unusual way of eating goes back more than 450 million years.
Top image: Alasdair James/Getty Images
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