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The longhorn cowfish (''Lactoria cornuta''), also called the horned boxfish, is a species of marine
ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...
belonging to the
family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...
Ostraciidae, the boxfishes. This species is 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 vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...
region and can grow up to long. Adults are reef fish, often solitary and territorial, and live around sand or rubble bottom up to a depth of . They are
omnivorous An omnivore () is an animal that regularly consumes significant quantities of both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize ...
, feeding upon
benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from the Ancient Greek word (), meaning "the depths". ...
algae, various
microorganisms A microorganism, or microbe, is an organism of microscopic size, which may exist in its single-celled form or as a colony of cells. The possible existence of unseen microbial life was suspected from antiquity, with an early attestation in ...
, and
foraminifera Foraminifera ( ; Latin for "hole bearers"; informally called "forams") are unicellular organism, single-celled organisms, members of a phylum or class (biology), class of Rhizarian protists characterized by streaming granular Ectoplasm (cell bio ...
ns that it strains from sediments,
sponge Sponges or sea sponges are primarily marine invertebrates of the animal phylum Porifera (; meaning 'pore bearer'), a basal clade and a sister taxon of the diploblasts. They are sessile filter feeders that are bound to the seabed, and a ...
s, polychaete worms from sand flats,
mollusks Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The num ...
, small
crustaceans Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of Arthropod, arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquat ...
, and small fish, able to feed on benthic
invertebrates Invertebrates are animals that neither develop nor retain a vertebral column (commonly known as a ''spine'' or ''backbone''), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordate subphylum ...
by blowing jets of water into the sandy substrate. Longhorn cowfish protect the coral reefs they live in by being predators of the invertebrates that destroy the reefs. They are also important in the growth and creation of coral reefs for this same reason.


Taxonomy

The longhorn cowfish was first formally described as ''Ostracion cornutus'' in the 10th edition of ''Systema Naturae'' published in 1758 by
Carl Linnaeus Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...
with its type locality given as India. In 1902
David Starr Jordan David Starr Jordan (January 19, 1851 – September 19, 1931) was the founding president of Stanford University, serving from 1891 to 1913. He was an ichthyologist during his research career. Prior to serving as president of Stanford Universi ...
and
Henry Weed Fowler Henry Weed Fowler (March 23, 1878 – June 21, 1965) was an American zoologist born in Holmesburg, Philadelphia, Holmesburg, Pennsylvania. He studied at Stanford University under David Starr Jordan. He joined the Academy of Natural Sciences in Ph ...
proposed the
subgenus In biology, a subgenus ( subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the ge ...
'' Lactoria'' within '' Ostracion'' and designated ''O. cornutus'' as its
type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...
. The 5th edition of ''
Fishes of the World ''Fishes of the World'' is a standard reference for the systematics of fishes. It was first written in 1976 by the American ichthyologist Joseph S. Nelson (1937–2011). Now in its fifth edition (2016), the work is a comprehensive overview of t ...
'' classifies this genus within the family Ostraciidae in the
suborder Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized ...
Ostracioidea within the
order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...
Tetraodontiformes Tetraodontiformes (), also known as the Plectognathi, is an order of ray-finned fishes which includes the pufferfishes and related taxa. This order has been classified as a suborder of the order Perciformes, although recent studies have found ...
.


Etymology

The genus name ''Lactoria'' means "milkcow", a reference to the large spines above the eyes resembling the horns of a cow. The fishes in this genus are known as cowfishes, as are some related species. The specific name ''cornutus'' means "horned", alluding to the large spines in front of the eyes.


Habitat

Its primary habitat is
coral reef A 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 group ...
s in
lagoons A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into '' coastal lagoons'' (or ''barrier lagoons'') a ...
, on reef flats, estuaries, bays, and on protected seaward reefs.Tresnati, J., Dolo, R., Aprianto, R., & Tuwo, A. (2020, September). Some population parameters of Longhorn Cowfish ''Lactoria cornuta'' (Linnaeus, 1758) in Laikang Bay, Takalar District, South Sulawesi, Indonesia (preliminary study). In IOP Conference Series: Earth and Environmental Science (Vol. 564, No. 1, p. 012014). IOP Publishing. Juveniles associate with '' Acropora'' corals. Depth range is , perhaps up to .


Distribution

Red Sea and East Africa eastward through Indonesia to
Marquesas The Marquesas Islands ( ; or ' or ' ; Marquesan: ' ( North Marquesan) and ' ( South Marquesan), both meaning "the land of men") are a group of volcanic islands in French Polynesia, an overseas collectivity of France in the southern Pacific ...
, northward to southern Japan. Including
Tuamotus The Tuamotu Archipelago or the Tuamotu Islands (, officially ) are a French Polynesian chain of just under 80 islands and atolls in the southern Pacific Ocean. They constitute the largest chain of atolls in the world, extending (from northwest to ...
, southern Korea, north to the
Ryukyu Islands The , also known as the or the , are a chain of Japanese islands that stretch southwest from Kyushu to Geography of Taiwan, Taiwan: the Ryukyu Islands are divided into the Satsunan Islands (Ōsumi Islands, Ōsumi, Tokara Islands, Tokara and A ...
of southern Japan, south to Australia and
Lord Howe Island Lord Howe Island (; formerly Lord Howe's Island) is an irregularly crescent-shaped volcanic remnant in the Tasman Sea between Australia and New Zealand, part of the Australian state of New South Wales. It lies directly east of mainland Port ...
. Tropical and subtropical waters. The specimens found in India are a new development in the last couple years, and it is speculated that cyclones or typhoons brought ''Lactoria cornuta'' to a new environment.


Description

There is no known
sexual dimorphism Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...
, 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 ichthyoplankton are
pelagic The pelagic zone consists of the water column of the open ocean and can be further divided into regions by depth. The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or water column between the sur ...
. Females generally are larger than males. Males grow to be 65–155 mm with an average of 103 mm, while females grow to be 83–250 mm with an average of 121 mm. Female longhorn cowfish also weigh more than males with a weight range of 17–156 g with an average of 33 g while males have a weight range of 12–116 g with an average of 26 g. 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 A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the unde ...
, from which the fins and tail protrude. They have large eyes immediately behind the horns. Their unique method of swimming, called ostraciiform swimming, causes them to look as if they are hovering. They have no pelvic skeleton, so they lack pelvic fins. The tail fin of the longhorn cowfish can be the same length as its body, as it relies on its fins for movement. They are slow swimmers and are easily caught by hand, making a grunting noise when captured. The cowfish are also able to produce two kinds of sounds using muscles connected to their swim bladder, hums and clicks. This species of cowfish is the most well-known cowfish species in the aquarium trade.


Defense

If severely stressed, this species may be able to exude deadly toxin, pahutoxin, 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 the boxfish and mimics
sea cucumber Sea cucumbers are echinoderms from the class (biology), class Holothuroidea ( ). They are benthic marine animals found on the sea floor worldwide, and the number of known holothuroid species worldwide is about 1,786, with the greatest number be ...
toxins in general properties. The horns of the Longhorn cowfish may have evolved to make it more difficult to swallow for predators. The horns of the boxfish can be used to ward off predators through charging at the predator. If damaged, these horns can grow back within a few months. These horns are mostly hollow and composed of mineralized
collagen Collagen () is the main structural protein in the extracellular matrix of the connective tissues of many animals. It is the most abundant protein in mammals, making up 25% to 35% of protein content. Amino acids are bound together to form a trip ...
fibers. Both the hard armor exoskeleton and the use of the toxic secretion are solid defenses against predators. There are also egg predators like
wrasse The wrasses are a family, Labridae, of marine ray-finned fish, many of which are brightly colored. The family is large and diverse, with over 600 species in 81 genera, which are divided into nine subgroups or tribes. They are typically small, ...
s and damselfishes. Larger species in the family are able to ward off the egg predators, but the Longhorn Cowfish spawn close to the substrate in order to hide themselves and their eggs from the predators.Moyer, J. T. (1979). Mating Strategies and Reproductive Behavior of Ostraciid Fishes at Miyake-jima, Japan. Japanese Journal of Ichthyology, 26(2).


Reproduction and development

This fish forms harems with 3–4 females in each one. The females spawn shortly after sunset, or during the day when there is a large amount of cloud cover. The spawning season lasts from February to early October. The oval eggs of species in the genus ''Lactoria'' hatch into the juvenile larvae. These larvae are distinct because they form the box carapace armor that is present on the longhorn cowfish. On
Pamban Island Pamban Island (, ''pāmpaṉ tīvu''), also known as Rameswaram Island, is an island located between peninsular India and Sri Lanka. It forms part of the Rameswaram taluk in the Ramanathapuram district of the Indian state of Tamil Nadu. It is ...
, the local belief was that when the land got separated, the cows on the island metamorphosed into these fish and fed on seaweed.


References


External links

* * * {{Taxonbar, from=Q664165 Lactoria Fish described in 1758 Taxa named by Carl Linnaeus