Wrasse are a large and varied group of shallow-water fish found around the world and known for being colourful. In Dorset five native species are commonly found with a sixth species, the Baillon’s wrasse, having arrived in recent years. With their vibrant colours they would not look out of place on a tropical coral reef. However, while they may be familiar to scuba-divers and anglers, they are less familiar to the rest of us despite living just off our shores.

The two largest members of this group both have an unusual life history with some individuals changing sex from female to male part-way through their life. Another wrasse species, the ballan wrasse, can grow to over half a metre long and live for around 30 years. They all start life as females and in their first year sport a stunning emerald green colour. As they grow they change colour to a mottled green or brown. While most ballan wrasse remain female, some change into males and it appears that the oldest of these tend to change colour over the years becoming a beautiful red or orange with white spots.

Ballan wrasse feed on hard-shelled snails and crustaceans, so to deal with the hard shells they have a special set of crushing teeth in their throat to complement their normal teeth. These pharyngeal teeth are arranged on a triangular plate called a Ballan cross, which can sometimes be found washed ashore after the fish has died. Historically these were prized by sailors who wore them as a lucky talisman to protect them from drowning.

The cuckoo wrasse is a little smaller than the ballan wrasse but to make up for its lack of size it displays the most vivid colours of all our British fish. All young cuckoo wrasse are females and are a peachy colour with bold alternating black and white spots along their spine. The females live in groups, sometimes called a harem, and may have a single male fish with them. Mature males are territorial and can remain faithful to their territory for several years. When the mature male dies the dominant female in the harem undergoes a complete sex change and becomes a male. At the same time she changes colour, losing her black and white spots, deepening the orange colour on her body and developing an electric blue head, tail and sides. In the breeding season the blue heads of male cuckoo wrasse can appear electrified, as if they are glowing from within.

So if our most colourful British fish have passed you by, why not take a closer look at your local marine life? Exploring rock pools or trying out the Kimmeridge Snorkel Trail might reveal some exotic-looking surprises. Our marine wildlife in Dorset can be spectacular and it’s waiting to be discovered. Find out more about Dorset’s sea creatures and where to see them at http://www.dorsetwildlifetrust.org.uk/living-seas.html