Fish are the largest and most diverse group of vertebrates on the planet. With an estimated 32 500 species they constitute approximately half of all the known
BOX 28.1 CATALOGUES AND KEY REFERENCES FOR IDENTIFICATION OF GREAT BARRIER REEF FISHES
Carpenter, K. E., and Niem. V. H. (Eds) (1998). 'FAO Species Identification Guide for Fishery Purposes. The living marine resources of the Western Central Pacific. Vols 1-6.' (FAO: Rome.)
Eschmeyer, W. N. (Ed.) (1998). Catalog of Fishes. Center for Biodiversity Research and Information, Special Publication 1. California Academy of Sciences. Available at www.calacademy.org/research/ichthyology/catalog/fishcatsearch.html.
Froese, R., and Pauly, D. (Eds) (2007). FishBase. World Wide Web electronic publication. Avaible at www.fishbase.org.
Hoese, D. F, Bray, D. J., Allen, G. R., and Paxton, J. (2006). Fishes. In 'Zoological Catalogue of Australia. Vol. 35.' (Eds. Beesley, P.L. and A. Wells.) 2248 pp. (ABRS and CSIRO Publishing: Australia.)
Lowe, G. R., and Russell, B. C. (1994). Additions and revisions to the checklist of fishes of the Capricorn-Bunker Group Great Barrier Reef Australia. Technical Memoir GBRMPA-TM-19, Great Barrier Reef Marine Park Authority, Townsville.
Nelson, J. S. (2006). 'Fishes of the World.' 4th edn. (John Wiley and Sons, Inc.: New York.)
Randall, J. E., Allen, G. R., and Steene, R. C. (1990). 'Fishes of the Great Barrier Reef and Coral Sea.' (Crawford House Press: Bathurst.)
Russell, B. C. (1983). 'Annotated checklist of the coral reef fishes in the Capricorn-Bunker Group Great Barrier Reef Australia.' Great Barrier Reef Marine Park Authority. Special Publication No. 1.
species of vertebrates. Moreover, the potential for discovering new species is far greater in fishes than any of the other groups of vertebrates. Even after three centuries the rate of discovery of new species remains undi-minished and fish experts estimate about 5000 marine species remain to be discovered and identified.
Although the diversity of fishes is relatively high, their distribution through the biosphere is taxonomically biased. For example the 11 952 fishes recorded from fresh water environments are strongly represented by just three groups, the carps, characins and catfishes that constitute 65% of the diverse fauna. Similar biases occur in the marine environment. Coral reefs are dominated by a single but complex group of bony fishes, the perciformes. These are perch-like fishes with spiny fin rays characterised by modifications to the feeding and locomotory apparatus that allow them to exploit a variety of food items ranging from microscopic sessile organisms to highly motile invertebrates and fishes.
The distribution of fish through the aquatic biosphere is also heavily biased. The majority of fish species occur in warm water with high local productivity, on shallow tropical marine reefs and in tropical lakes and streams. Tropical reefs make up less than 1% of the total marine habitat and freshwater species occupy less than 1% of the world's aquatic habitat. Thus, the greatest diversity of fishes occurs within a tiny fraction of the Earth's aquatic habitats, in shallow productive waters at low latitudes.
The diversity of marine reef fishes is reflected in the following figures. The total number of species is approximately 16 000 with 10 000 occurring in shallow tropical waters. The diversity of coral reef fishes has a strong geographical focus, with about 2400 species occurring in the Indonesian and Philippine archipelagos. The majority of these are perciformes that have an extended evolutionary history to the start of the Ceno-zoic. Although some lineages were present in the Cretaceous period at 80-100 million years ago (My) the great morphological variety that we see in the present day was not established until the Eocene period, approximately 50 My.
The most speciose groups of present day coral reef fishes are gobies (family Gobiidae), wrasses (Labridae), groupers (Serranidae), damselfishes (Pomacentridae), cardinalfishes (Apogonidae) and blennies (Blenniidae). In addition, many groups such as butterflyfishes (Chaetodontidae), surgeonfishes (Acanthuridae), par-rotfishes (Scaridae) and snappers (Lutjanidae) are also conspicuous and diverse in terms of species numbers, and with wrasses and damselfishes make up a majority of the individual fishes observed on coral reefs. In terms of size, coral reef fishes are highly skewed towards the lower end of the size range, with the majority of reef fishes being less than 20 cm in length. In addition, many reef fish species are locally rare, and a characteristic of fish communities on coral reefs is that they are dominated by a few very abundant species and numerous small rare species.
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