The cuckoo wrasse (Labrus mixtus) is one of four wrasse species commonly found around the rocky coasts of the United Kingdom. A large, slender and highly colourful fish, males and females look very different. Females are orangey-pink with distinctive black and white blotches along their backs, while males display striking electric blue markings on the head and back with bright orange fins.
Cuckoo wrasse feed mainly on molluscs such as limpets and mussels, as well as crustaceans, using their powerful teeth and jaws to crush shells. They may also take small fish when the opportunity arises. They have another set of teeth within their throat, called pharyngeal teeth. This helps them break down food further to aid the fact that they are agastric meaning they lack a stomach.
Remarkably, cuckoo wrasse begin life as females. They are protogynous hermaphrodites, meaning the dominant female can change sex and become male if the resident male disappears — ensuring the reef always has a breeding male.
