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Longhorn cowfish

Longhorn cowfish

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The longhorn cowfish, Lactoria cornuta, is a variety of boxfish
Ostraciidae is a family of squared, bony fish belonging to the order Tetraodontiformes, closely related to the pufferfishes and filefishes. Fish in the family are known variously as boxfishes, cofferfishes, cowfishes and trunkfishes...

 from the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Ostraciidae, recognizable by its long horns that protrude from the front of its head, rather like those of a cow or bull. They are a resident of the Indo-Pacific
The Indo-Pacific is a biogeographic region of the Earth's seas, comprising the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the seas connecting the two in the general area of Indonesia...

 region and can grow up to 20 inches long. Whilst badly suited to the home aquarium, the cowfish is becoming increasingly popular as a pet.

Adults are reef fish
Reef fish
Coral reef fish are fish which live amongst or in close relation to coral reefs. Coral reefs form complex ecosystems with tremendous biodiversity. Among the myriad inhabitants, the fish stand out as particularly colourful and interesting to watch. Hundreds of species can exist in a small area of a...

, often solitary and territorial, live around sand or rubble bottom up to a depth of 50 m. They are omnivorous, feeding upon benthic
Benthic zone
The benthic zone is the ecological region at the lowest level of a body of water such as an ocean or a lake, including the sediment surface and some sub-surface layers. Organisms living in this zone are called benthos. They generally live in close relationship with the substrate bottom; many such...

 algae, various microorganisms, and foraminiferan
The Foraminifera , or forams for short, are a large group of amoeboid protists which are among the commonest plankton species. They have reticulating pseudopods, fine strands of cytoplasm that branch and merge to form a dynamic net...

s that it strains from sediments, sponges, polychaete worms
The Polychaeta or polychaetes are a class of annelid worms, generally marine. Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made of chitin. Indeed, polychaetes are sometimes referred to as bristle worms. More than 10,000...

 from sand flats, mollusks, small crustaceans, and small fishes, able to feed on benthic invertebrates by blowing jets of water into the sandy substrate.


Its primary habitat is coral reef
Coral reef
Coral reefs are underwater structures made from calcium carbonate secreted by corals. Coral reefs are colonies of tiny living animals found in marine waters that contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups. The polyps...

s in lagoons, on reef flats, and on protected seaward reefs. Juveniles associate with Acropora
Acropora is a genus of scleractinian coral in the Phylum Cnidaria. Some of its species are known as table coral, elkhorn coral and staghorn coral. There are currently 149 described species...

 corals. Depth range is 3.3–148 ft (1–45 m, perhaps up to 100 m).


Red Sea and East Africa eastward through Indonesia to Marquesas, northward to southern Japan. Including Tuamotus
The Tuamotus or the Tuamotu Archipelago are a chain of islands and atolls in French Polynesia. They form the largest chain of atolls in the world, spanning an area of the Pacific Ocean roughly the size of Western Europe...

, southern Korea, north to the Ryukyu Islands
Ryukyu Islands
The , also known as the , is a chain of islands in the western Pacific, on the eastern limit of the East China Sea and to the southwest of the island of Kyushu in Japan. From about 1829 until the mid 20th century, they were alternately called Luchu, Loochoo, or Lewchew, akin to the Mandarin...

 of southern Japan, south to Australia and Lord Howe Island
Lord Howe Island
Lord Howe Island is an irregularly crescent-shaped volcanic remnant in the Tasman Sea between Australia and New Zealand, directly east of mainland Port Macquarie, and about from Norfolk Island. The island is about 11 km long and between 2.8 km and 0.6 km wide with an area of...

, and off southern Africa in the Atlantic. Tropical and subtropical waters.


Appendage Number (total)
Dorsal spines 1
Dorsal soft rays 8 - 9
Anal spines 0
Anal soft rays 8 – 9
Caudal fin rays 9 - 10

There is no known sexual dimorphism
Sexual dimorphism
Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...

, so both male and female display a yellow to olive base color, which is decorated with white or bluish spots. Paired courtship just before or after sunset. Eggs and larvae are pelagic.

One distinction from other fish is the lack of a gill cover, which is replaced by a small slit or hole.
The hexagonal plate-like scales of these fish are fused together into a solid, triangular, box-like carapace, from which the fins and tail protrude.
Their unique method of swimming, called ostraciform swimming, causes them to look as if they are hovering.
They have no pelvic skeleton, so they lack pelvic fins.
They are such slow swimmers cowfish are easily caught by hand, making a grunting noise when captured.
This is the most well-known cowfish species in the aquarium trade.


If severely stressed, this species may be able to exude deadly toxin, ostracitoxin
When under stress, a boxfish will release the Ostracitoxin toxin . It is an ichthyotoxic, hemolytic, nonprotein poison in the mucous secretions of their skin...

, an ichthyotoxic, hemolytic, heat-stable, non-dialyzable, non-protein poison in the mucous secretions of their skin. It is apparently unique among known fish poisons; it is toxic to boxfish and resembles red tide
Red tide
Red tide is a common name for a phenomenon also known as an algal bloom , an event in which estuarine, marine, or fresh water algae accumulate rapidly in the water column and results in discoloration of the surface water. It is usually found in coastal areas...

 and sea cucumber toxins in general properties.