Colorful sea slug is one of thousands of tiny but beautiful underwater sights

Sea slugs are one of the ocean’s most diverse and beautiful creatures. Intensely coloured and unique in shape, size, and texture, they are a sight to behold. With more than 3,000 species known, and more being discovered every year, there is an almost endless variety to catalogue and study. Their diminutive size makes them difficult to find, and many scuba divers and underwater photographers work exceptionally hard to find more than a few on each dive.

Slugs are wonderful subjects for photography and videography as they are slow moving and easy to keep track of once found. Their bright colours help in locating them, although some of them blend in so well with their surroundings that they are nearly perfectly camouflaged. Much like snails, sea slugs appear similar in movement, feeding, and shape, except that they lack the external shells.

This is a Chromoris strigata Rudman, one of many sea slugs that can be found in the Pacific Ocean. It was found making its way slowly over the coral in Papua New Guinea, approximately 10m (30 feet) from the surface. Its bright colouring makes it very conspicuous, and easily found by predators, but those colours actually suggest to most fish that the slug is distasteful, or even toxic for them to eat. Many sea slugs accumulate the poisons from their diet of algae and se sponges and they truly do taste awful for predators. Sea slugs are highly specialized and often eat only one type of food, whether it be coral, sea anemone, sponge, or even other slugs. This specialized diet may contribute to their inedibility in many cases, which is a perfect means of survival.

Amazingly, some species of sea slugs are capable of making sounds with a rapid opening of their mouths. This sharp intake of water creates a sound which is similar to a small piece of metal striking a glass surface. The sound is reportedly audible from as far as 4m (12 feet) away.

Scuba divers are fortunate to experience a world that is indescribably beautiful. Sea slugs as colourful as this one are a perfect example of the strange and fascinating sights awaiting those who are adventurous enough to descend beneath the waves.