The beautiful Blue Dragon Nudibranch (Pteraeolidia ianthina) is quite an amazing beast. It absorbs algal zooxanthellae from its food and these photosynthesise inside its body lending it the beautiful range of colours it can be found in. They also absorb and use the stinging nematocyst cells of their prey and these offer up defence for the dragons by way of a painful sting.

This particular specimen was one of the largest I have seen and the colours were very striking. Shooting head on like this you can see the body trailing off out of focus in the background of the shot.