Take some eccentric patterns, a glittering range of kaleidoscopic colours and some very unusual shapes and, hey presto, you have a nudibranch!

Belonging to the animal subclass Opisthobranchia they should be known as sea slugs, but then this name doesn’t do justice to the extraordinary colours, patterns and fascinating behaviour of nudibranchs which make them much beloved by underwater photographers.

With over three thousand recorded species of Nudibranchs the diversity is truly enormous. They can vary in adult size from under one inch (20mm) to nearly two feet (600mm).

Slow moving and lacking a shell you could think these little creatures are defenceless. In fact they are masters of defence. The diet of some nudibranchs includes jellyfish, hydroids and anemones and as they eat they absorb their prey’s stinging cells, intact and unfired, and transfer them to little sacs on their backs called cerata which they then use to discharge a very painful surprise for any animal that tries to eat them.

Some use camouflage as the secret to their survival while others which consume sponges use the toxins they digest to produce foul-tasting, acid secretions.

All a bit gruesome but they are still truly beautiful.