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to genera, with some to species (Zostera asiatica and Z. marina)

Seagrass habitats in the region, as elsewhere in the world, have been lost, fragmented and damaged by development and poor catchment management, through practices such as sewage and stormwater discharges, urban runoff, dredging, boating and land reclamation.

Seagrass meadows play a key ecological role in the region’s coastal ecosystems and the loss of seagrass beds is considered to be one of the most serious issues facing the marine environment. Seagrass habitats support high primary productivity and host a wide variety of associated fauna including commercially important fishes.

The extent of seagrass beds is a good indicator of the ecological health of the marine environment...

Haliotis spp. – 4 species

Abalones are highly-valued but slow growing, herbivorous marine snails. They belong to a large class of molluscs (Gastropoda) with single-structured shells. There are over 100 species worldwide in the single genus Haliotis, which means ‘sea ear’, a reflection of the flattened shape of the shell. It is no surprise then that it is called ‘Oreille de Mer’ in France. Abalone shells can be oval or rounded, with a row of respiratory pores and large dome towards one end. They are edible molluscs and considered a delicacy. The inner shell of abalone, which has an iridescent green, blue, or pink sheen, is a source of mother-of-pearl

The strong, muscular foot generates enough suction to allow the abalone to fix itself firmly to rocky surfaces, and enables...

Turbo cornutus

The horned turban (Turbo cornutus) is an edible mollusc, a member of the class Gastropoda, the largest class of molluscs containing over 35,000 living species and 15,000 fossil forms. The one – piece (univalve) shell is usually coiled or spiralled, although in some cases, such as nudibranchs, the shell is completely absent.

The gastropod usually has a distinct head with one or two sensory tentacles and a mouth that is often equipped with a rasp-like tongue called a radula. The head can be drawn into its body. The underside of the animal is modified into a long, flattened foot, used by benthic (bottom-dwelling) species for mobility...

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...

Apostichopus japonicus and Stichopus nigirpunctatus

Sea cucumbers (Holothuroidea) are a group of worm-like and usually soft-bodied echinoderms that are found in nearly every marine environment, but are most diverse on tropical shallow-water coral reefs. They range from the intertidal zone, where they may be exposed briefly at low tide, to the floor of the deepest oceanic trenches (an unidentified specimen was taken from the Philippine trench in 1951 at 10,190 metres) generally preferring sandy and muddy habitats.

There are approximately 1400 extant species which come in many forms. Generally cucumber shaped, some adults of diminutive species may not exceed 1cm in length, while one large species (Synapta maculata) can reach lengths of 3 m! (One report of this species at 5m long on t...

Acanthaster planci

Sea stars (group name Stelleroidea), are sometimes called starfish, though lacking both vertebrae and fins, they are not real fish. There are two sub-types of sea stars: Asteroideas are the true sea stars and sun stars, whereas Ophiuroideas are brittle stars and basket stars.

Ophiuroid means ‘snake-like’, referring to the form and motion of the arms. The arms of brittle stars are easily broken off, but will regenerate in a few days to weeks. Sea stars can also regenerate arms that are broken off, but for most species, the central region of the body must remain intact

Class Asteroidea, the true sea stars, contains about 1700 living species of these echinoderms...

Echinometra spp

Sea urchins are often used as indicator organisms in public aquaria 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. Sea urchins are highly sensitive to air and direct sunlight, and often use bits of shell and pebbles as sunshade ‘umbrellas’.

Sea urchins (echinoderms) are a group of marine invertebrates that can be found in almost every major marine habitat from the poles to the equator and from the inter-tidal zone to depths of more than 5,000 metres. There are around 800 extant species and the group has a long and detailed fossil record stretching back many millions of years...

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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Chaetodontidae

The butterflyfish family is a large and well known group of tropical species. They are mostly of small size with oval-shaped bodies which are deep and greatly compressed. The dorsal fin is continuos along the back and is not divided between the anterior spinous part and the spineless posterior portion. The tail may be rounded, truncated, or emarginated on its posterior border, but is never forked. The head bears a small mouth which contains flexible, brush-like or comb-like teeth. Within this family some members have a sharp spine on the lower back corner of the preopercle. These are true angel fishes, and with the presence of this spine can be distinguished and separated from true Butterfly Fishes, placing them in a separate family, Pomacanthidae.

Butterflyfish a...