Porcupine Ray (Urogymnus asperrimus): The strange-looking Porcupine Ray is not a resident of the Maldives but is a frequent visitor. Covered with plate-like tenticles and sharp thorns, it is also known as the Roughskin Stingaree, Rough-skinned Ray, Solander’s Ray and Thorny Ray. The Porcupine Ray has an oval-shaped disc that can be up to a metre in disc width. Its dark-tipped tail with its dark tip lacks stinging spines and skin folds. The Ray's colour is whitish-grey to brown above and white below. This one was photographed in the lagoon of Biyadhoo Atoll.

Two-lined Monacle Bream (Scolopsis bilineata): A frequently-seen inhabitant of the Lagoon’s rubble area, the 20 cm Two-lined Monacle Bream looks as though it can’t make up its mind. It darts from one place to another stopping dead each time in a questioning way. In fact it has excellent eyesight and looks for signs of worms and small creatures in the rubble and sand. The slightest movement .. and lunch is served. Look for a grey body, the distinctive white head-stripe outlined in black that runs from under the eye to the middle of the back, the outsized eye and the darkened skin under the dorsal fin.

Nudibranch: This is the famous mollusc without a shell i.e. 'nudi' in Latin. Most of them have very bright colours, this type – Phyllidia in particular, to warn off predators. They move like a slug so they are always vunerable. Some species feed on the fire coral, Hydrozoa, and are able to transfer a part of the stinging cells into their own tissues. Others cover themselves in a pseudo-shell made up of the calcerous spicules of the sponges on which they feed. Still others have special glands that secrete repellent substances. Whatever their form they make great photographs for the snorkeller.

Not So Great Barrier Reef. Half of the Great Barrier Reef's coral has disappeared in the past 27 years and less than a quarter could be left within a decade unless action is taken, a landmark study has found. A long-term reef investigation by scientists at Townsville's Australian Institute of Marine Science found that of the 50% destroyed coral 24% had been wiped out by intense tropical cyclones, 21% by Crown of Thorns Starfish outbreaks and 5% by coral bleaching.

Even if nothing changes for the worse in the next 20 years the reef will be in a perilous state. Global warming models project increases in water temperatures will lead to more intense cyclones. The frequency of Crown of Thorns outbreaks has increased from one in every 50-80 years before European agricultural runoff, to the currently observed frequency of one in every 15 years. Runoff waters carrying fertilisers and other agricultural nutrients into the ocean were thought to increase the survival of Crown of Thorns larvae by encouraging the growth of algae eaten by the offspring. Warmer waters were also responsible for coral-bleaching events, where the tiny organisms living inside the coral skeleton "bleached" and died with the rising temperatures. The growing frequency and intensity of mass coral bleaching is directly attributable to rising atmospheric greenhouse gases.

"Coral cover is the simplest index of reef health, and the health of the Great Barrier Reef has gone down dramatically," said institute senior scientist Hugh Sweatman. "The coral provides shelter and food for thousands of organisms so you don't just lose the corals themselves you lose the species that depend on them."

At 214 reef sites surveyed, the coral cover halved from 28% to 13.8% between 1985 and 2012. Two-thirds of the loss occurred since 1998. Only three of the 214 reef sites exhibited no impact. The coral damage was most pronounced in the central and southern regions of the 2000-kilometre reef, with the remote northern section remaining largely unaffected.