The Short-nosed Unicornfish

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Pesci Unicorno intotheblue.it

Unicornfishes Pesce unicorno Acanthuridae - intotheblue.it

Unicornfishes Pesce unicorno Acanthuridae – intotheblue.it

The short-nosed unicornfish or spotted unicornfish (Naso brevirostris) is a species of unicornfish in the family Acanthuridae.

Naso brevirostris is widespread throughout the Indian and Pacific Oceans.  Another species, Naso maculatus , may also be called the spotted unicornfish.

This species is listed as “least concern” on the IUCN Red List of Threatened Species, and there are no observed declines as a result of commercial or recreational fishing.

The short-nosed unicornfish dwells in mid-waters along steep outer lagoon, in rocky shore and seaward reef drop-offs, and prefers water temperatures ranging from 22.4 to 29° Celsius,

Naso brevirostris can reach a maximum length of 35 centimetres. These fishes have an elongate, oval body, with a short snout and a small, protrusible mouth. They are olivaceous brown to bluish grey in color, with a prominent horn, many small dark spots on head and short irregular lines on sides of body. The anterior par of the body is rather pale. The tail is whitish with dark blotch. The caudal knives are relatively larger in males (sexual dimorphism). Pesci Unicorno intotheblue.it

(extract from Wikipedia)

 

Unicornfishes Pesce unicorno Acanthuridae - intotheblue.it

Unicornfishes Pesce unicorno Acanthuridae – intotheblue.it

Unicornfishes Pesce unicorno Acanthuridae - intotheblue.it

Unicornfishes Pesce unicorno Acanthuridae – intotheblue.it

The coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups.

Coral belongs to the class Anthozoa the animal phylum Cnidaria, which includes sea anemones and jellyfish. Unlike sea anemones, corals secrete hard carbonate exoskeletons that support and protect the coral. Most reefs grow best in warm, shallow, clear, sunny and agitated water. Coral reefs first appeared 485 million years ago, at the dawn of the Early Ordovician, displacing the microbial and sponge reefs of the Cambrian.

Sometimes called rainforests of the sea, shallow coral reefs form some of Earth’s most diverse ecosystems. They occupy less than 0.1% of the world’s ocean area, about half the area of France, yet they provide a home for at least 25% of all marine species, including fish, mollusks, worms,echinoderms, sponges, tunicates and other cnidarians.

Coral reefs flourish in ocean waters that provide few nutrients. They are most commonly found at shallow depths in tropical waters, but deep water and cold water coral reefs exist on smaller scales in other areas.

Coral reefs deliver ecosystem services for tourism, fisheries and shoreline protection. Coral reefs are fragile, partly because they are sensitive to water conditions. They are under threat from excess nutrients (nitrogen and phosphorus), rising temperatures, oceanic acidification, overfishing (e.g., from blast, fishing, cyanide fishing, spearfishing on), sunscreen use, and harmful land-use practices, including runoff and seeps (e.g., from injection wells and cesspools).

Over 4,000 species of fish inhabit coral reefs. The reasons for this diversity remain unclear. Hypotheses include the “lottery”, in which the first (lucky winner) recruit to a territory is typically able to defend it against latecomers, “competition”, in which adults compete for territory, and less-competitive species must be able to survive in poorer habitat, and “predation”, in which population size is a function of postsettlement piscivore mortality. Healthy reefs can produce up to 35 tons of fish per square kilometer each year, but damaged reefs produce much less.

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Questo articolo è stato scritto il / This article was written on 08/06/2018