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Haliotis spp.

Abalones are slow-growing, herbivorous marine snails. They belong to a large class of molluscs (Gastropoda) with singlestructured 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.

The strong, muscular foot generates enough suction to allow the abalone to fix itself firmly to rocky surfaces. They are found from the inter-tidal to the depth limit of marine plants, some 80 -100m, from tropical to cold waters.

The related endemic Chilean Abalone or ‘Loco’ (Concholepas concholepas) is from a different gastropod fami...

Lobsters have recently suffered a dramatic demographic decline; entire populations have been annihilated by intensive fishing, especially where tourism abounds. The diversity of lobsters, molluscs and shrimp is low in the region, with perhaps less than ten species of lobster to be found. However there are two endemic species of lobster, the Juan Fernandez rock lobster (Jasus frontalis) and the Chilean jagged or spiny lobster (Projasus bahamondei).

The Chilean jagged lobster, is generally not commercially exploited, but is frequently landed as bycatch. Other lobsters to be found will include the squat lobster (Pleuroncodes monodon) and Palinuras spp...

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 nonexistence during your dive tells us a lot. Like all indicators, it is valuable if you can record the particular species you sight. However, recording the total number of groupers is just as important...

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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Mussismilia spp.

Hard corals are also referred to as stony corals, and are members of the order Scleractinia. Hard Corals can be differentiated from other types of corals by their calcium skeleton or base. These corals are often broken down into two groups by their polyp type: small polyp stony corals (SPS) and large polyp stony corals (LPS). Live corals are found throughout the world in tropical waters on coral reefs. Most of these corals are found at depths no greater than 50 metres.

Hard corals are similar to anemones in that both animals use a mechanism called a nematocyst to deliver a sting to ward off predators, or maintain their space on the reef from other species of competing corals. Some species of LPS have sweeper tentacles that can reach several inches long at night...

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...

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...

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. Like all indicators, it is valuable if you can record the particular species you sight. However, recording the total number of groupers is just as important...

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.

earthdive wants you...

Lutjanus spp.

The snappers are a large and diverse group of robustbodied, carnivorous fishes. Most species possess relatively large mouths with stout canine teeth and bodies covered with relatively large, coarse scales. They are frequently brightly coloured. They are demersal (spending most time swimming close to the sea bed) in some cases down to 450m and are found in the tropical and sub topical waters of the Atlantic, Indian and Pacific Oceans. There are over one hundred individual species globally, but within the Pacific Coast Sub-tropical eco region there are only a limited number of species that you are likely to see at diving depth, and these will tend to be in the warmer waters of the region.