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Pecten maximus and Chlamys islandica

Scallops are bivalve molluscs with scalloped, fan-shaped shells (valves) whose shape and colour have inspired artists, architects and designers for centuries.

The shells are further characterized by radiating ribs or grooves and concentric growth rings. Near the hinge, where the two valves (shells) meet, the shell flares out on each side to form small “wings”. Just inside each valve along the edge of the mantle there a row of short sensory tentacles and a row of small blue eyes.

A single adductor muscle, sometimes called the ‘eye’ in culinary circles, opens and closes the two valves. Because they are active swimmers, the adductor muscle is more developed in the scallop than in oysters and clams...

Zeus faber

The John Dory (Zeus faber) is a distinctive fish with a worldwide distribution. In the Eastern Atlantic it can be found from Norway to South Africa and also in the Mediterranean and Black Seas. In the Western Pacific it occurs in the waters of Japan, Korea, Australia and New Zealand.

These thin, deep-bodied predatory fish are weak swimmers, with an oval flat body and large spiny head. Their normal strategy is to stalk their prey head on, using their thinness to their advantage, before extending their large oblique a mouth to suck in an unwary victim.

This species is dark brown as juveniles and silvery as adults. There is a large dark grey blotch ringed with white on the side of the body. This blotch gives rise to one of the common names for this species, St Peter’s fish...

Pelecypoda

Mussels are marine molluscs of the class Pelecypoda, which means hatchet-foot. They are filter-feeding bivalves, having a shell consisting of two valves, or movable pieces, hinged by an elastic ligament. Within the shell there is a fleshy layer of tissue called the mantle with a cavity (the mantle cavity) between the mantle and the body wall proper. The mantle secretes the layers of the shell, including the inner nacreous, or pearly, layer. Nacreous layers can also be formed around a foreign body in reaction to irritation. A muscular hatchet-shaped foot projects from the front end of the mollusc, between the valves. This foot is used for burrowing, and, in some bivalves (e.g., razor clams), to swim.

Bivalves differ in their habits: some, such as the oysters and marine mu...

Lobsters, like shrimps and crabs, are decapods – literally meaning 10 legs – and can be found in all of the world’s tropical and sub-tropical seas as well as more temperate waters. They are predatory, nocturnal animals with a vividly decorated coat. They are often numerous locally; they linger in crevices (with their long antennae sticking out) during the day and hunt small benthic organisms at night, but they also feed on organic detritus whenever they happen across it. As with all crustaceans, the lobster moults or sheds its shell to grow.

Up until the end of the 19th century lobster was so plentiful that it was often used as fish bait. Sadly, with lobster’s ever-increasing popularity those days are now gone forever...

Found in most oceans of the world, butterfly fish are small, thin, disk-shaped fish with pointed noses. There are many varieties, the four-eyed butterfly probably being the most common from New England to the Caribbean. Others include the spotfin, the banded, and the reef butterfly.

Many of these fish have a dark band running vertically through each eye. This helps the fish camouflage themselves on the coral reefs where they live. Most butterfly fish have pointed snouts, very useful for plucking out the small coral animals and getting into small crevices for tiny invertebrates which they feed on.

Yellow, white, and black are the most common colours for butterfly fish. The four-eyed is pale yellow or whitish, with a dark eye band and a large dark spot on the tail...

Diadema spp.

Sea urchins are often used as indicator organisms in public aquariums to determine whether the system is functioning properly. These organisms are extremely sensitive to water conditions and are first to show signs of stress, seen when their spines are laid down or are shed.

Warning! Some sea urchins are covered with sharp venom-filled spines that can easily penetrate and break off into the skin – even through a wetsuit. The DAN (Divers Alert Network) website contains useful information on how to handle the unfortunate effects of accidental brushes with these and other poisonous marine organisms. Check out www.diversalertnetwork.org for any information that you need.

Sea urchins (echinoderms) are a group of marine invertebrates that can be found in almost every maj...

They have travelled the oceans and have outlived the dinosaurs. They have become an integral part of the traditional culture of many coastal indigenous peoples throughout the world. Today, all but one of the species features on the IUCN RED List as endagered or critically endangered. Extinction looms!

There are only a few large nesting populations of the green, hawksbill and loggerhead turtles left in the world. There are no large nesting populations of Kemp’s ridly turtle.

Until fairly recent times, their long presence in the trpical and sub-tropical seas and beaches of the planet seemed set to continue...

Serranidae

When people talk about coral reefs, fishermen tend to shrug their shoulders and complain about snagged lines and torn nets. But when you talk about groupers, they suddenly sit up and pay attention. Groupers are among the economically most important fishes of the coral reef, because of their popularity as food. Yet without the coral reef there would probably be no groupers. For this reason, groupers are an extremely important indicator species and your record of their existence or non-existence during your dive tells us a lot.

The goliath grouper (Epinephelus itajara), sometimes called the jewfish is classified as critically endangered on the IUCN Red List. Found in shallow, inshore waters to depths of 45m, this indicator prefers areas of rock, coral, and mud bottoms...

Identifying sharks in the wild is a great challenge! While scientists can spend weeks examining every detail of a species, divers may encounter a shark for only a few seconds or minutes. Many species look alike and one individual may not be identical to the next. There are, however, relatively few species in any one specific dive site and with some preparation and a little practice it is possible for all of us to recognise the more common and distinctive species. The key to successful shark identification underwater is a process of elimination, based on a mental checklist of the main features to look for in every animal encountered. One feature alone is rarely enough for a positive identification, so gather as much information as you can before drawing firm conclusions.

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Pagrus auratus

Strictly, or scientifically speaking, the pink snapper (Pagus auratus) is not actually a “snapper” at all! The snappers are a large and diverse group of robust-bodied, carnivorous fishes and belong to the family Lutjanidae. Like many other Australian species, the pink snapper inherited its name from the northern species it most closely resembles, but is in fact a member of the family Sparidae, which are sea bream or porgies.

The pink snapper is a very attractive fish, silvery in colour, with a pink to brown upper body. The sides are sprinkled with bright blue spots that are more prominent in juveniles. The top, tail and side fins are also pink, while the bottom fins range in colour from pale-pink to creamy-white.

Snapper have been known to live 30 years – a ri...