Category America South – Pacific coast – temperate

Sea urchins 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 (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. All echinoderms have tube-feet and these play a very important role in feeding and respiration. Echinoids move by means of spines and climb and cling on to hard substrata by means of their tubefeet. The spines also offer the primary means of defence.

Sea urchins are herbivores and feed in a variety...

Concholepas concholepas

Gastropoda is the largest and most successful class of mollusks (phylum Mollusca), containing over 35,000 living species and 15,000 fossil forms. The shell of gastropods is of one piece (called univalve) and usually coiled or spiraled as in snails, periwinkles, conches, whelks, limpets, and abalones.  Concholepas concholepas is a gastropod and lives along the coasts of Peru and Chile in South America.

The inhabitants call it ‘loco’ and collect it for eating.

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...

Pyura chilensis

Tunicates, commonly called sea squirts, are a group of marine animals that spend most of their lives attached to docks, rocks or the undersides of boats. To most people they look like small, colored blobs. It often comes as a surprise to learn that they are actually more closely related to vertebrates like ourselves than to most other invertebrate animals. Tunicates are part of the phylum Urochordata, closely related to the phylum Chordata that includes all vertebrates.

Because of these close ties, many scientists are working hard to learn about their biochemistry, their developmental biology, and their genetic relationship to other invertebrate and vertebrate animals. A tunicate is built like a barrel...

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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