| Snakehead | |
|---|---|
| Northern snakehead, Channa argus | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Perciformes |
| Suborder: | Channoidei |
| Family: | Channidae |
| Genera | |
The snakeheads are members of the freshwater perciform fish family Channidae, native to Africa and Asia. These elongated, predatory fish are distinguished by a long dorsal fin, large mouth and shiny teeth. They breathe air with a suprabranchial organ, a primitive form of a labyrinth organ. The two extant genera are Channa in Asia and Parachanna in Africa, consisting of 30-35 species.
They have become notorious as invasive species, to the extent of becoming a byword for monster in popular culture.
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The size of the snakehead species differs greatly. "Dwarf snakeheads", such as Channa gachua, grow to 10 inches (25 cm). Most snakeheads grow up to 2 or 3 feet (60–90 cm). Two species (Channa marulius and Channa micropeltes) can reach a length of more than 1 meter and a weight of more than 6 kg.
Snakeheads are thrust-feeders which consume plankton, aquatic insects, and mollusks when small. As adults, they mostly feed on other fish, such as carp, or on frogs. In rare cases, small mammals such as rats are taken.
The giant snakehead (Channa micropeltes) is native throughout Asia, and is the most aggressive snakehead. It can grow to around 1 meter in length.
Channidae are well-represented in the fossil record and known from numerous specimens. Research indicates snakeheads likely originated in the south Himalayan region of Indian subcontinent (modern-day northern India and eastern Pakistan) at least 50 million years ago (Ma), during the Early Eocene epoch. By 17 Ma, during the Early Miocene, Channidae had spread into western and central Eurasia, and by 8 Ma, during the late Tortonian, they could be found throughout Africa and East Asia.[1] As Channidae are adapted to climates of high precipitation with mean temperatures of 20°C (68°F), their migrations into Europe and Asia correspond to the development of the Intertropical Convergence Zone, which increased air humidity, and the intensification of the East Asian monsoon, respectively. Both weather patterns emerged due to greater vertical growth of the Alps, Pyrenees, and Himalayas, which affected Eurasian climactic patterns.[1]
Snakeheads can become invasive species and cause ecological damage because they are top-level predators, meaning they have no natural enemies outside of their native environment. Not only can they breathe atmospheric air, but they can also survive on land for up to four days, provided they are wet, and are known to migrate up to 1/4 mile on wet land to other bodies of water by wriggling with their body and fins. National Geographic has referred to snakeheads as "Fishzilla"[2][3][4] and the National Geographic Channel reports that the "northern snakehead reaches sexual maturity by age 2 or 3. Each spawning-age female can release up to 15,000 eggs at once. Snakeheads can mate as often as five times a year. This means in just two years, a single female can release up to 150,000 eggs." [2]
It is illegal to keep snakeheads as pets in many countries, as they have become an invasive species.
Humans have been introducing snakeheads to nonindigenous waters for over 100 years. In parts of Asia and Africa, the snakehead is considered a valuable food fish, and is produced in aquacultures (fisheries motivation) or by ignorance (as was the case in Crofton, Maryland). Some examples of the introduction of snakeheads to nonindigenous waters include:
Snakeheads became a national news topic in the US because of the appearance of northern snakeheads spawning in a Crofton, Maryland pond in 2002.[5][6] Northern snakeheads became permanently established in the Potomac River around 2004,[7] and possibly established in Florida.[5] Apparently unestablished specimens have been found in Wawayanda, New York,[8] two ponds in Philadelphia, Pennsylvania[7] and reservoirs in North Carolina.[5]
From 2002 to 2003, one Los Angeles supermarket was found to have illegally sold approximately $25,000 worth of live snakeheads, which caused breakouts in local ecosystems. [9]
In what was determined by the Army Corps of Engineers to be an isolated incident, a fisherman caught a single snakehead on October, 2004 while fishing from Lake Michigan at Burnham Harbor in Chicago, Illinois.[10][11][12] According to the United States Environmental Protection Agency, snakeheads have also been spotted in California, Florida, Hawaii, Maine, Maryland, Massachusetts, Arkansas and Rhode Island.[13]
On April 25, 2011, a northern snakehead was found above Virginia's Great Falls near Whites Ferry. Great Falls was supposedly a natural barrier that the fish was unable to cross. It is apparently the first time a northern snakehead was found above the falls. [14]
In May 2011, a Brooklyn fish importer was arrested for importing 350 live snakeheads into New York. He had tried to pass the fish off as Chinese black sleepers (Bostrychus sinensis) in an effort to mislead customs. He also admitted to importing six more shipments in 2010. It is unknown if any of the fish had been released into local waterways.[15]
On August 10, 2011, a teenager was bitten by a northern snakehead while kayaking on Beck's Pond in Bear, Delaware. He had attempted to capture the snakehead's young.
On August 16, 2011, Delaware Department of Natural Resources and Environmental Control fisheries biologists captured a 25-inch snakehead in Beck's Pond which they asserted had been illegally introduced. Officials warned that the snakeheads are known for aggressively protecting their young, and people should not try to catch the smaller fish.[16]
A report from Lincolnshire in the United Kingdom turned out to be a hoax.[17]
A reported catch from the Welland Canal in Canada turned out to be a misidentified specimen of Amia calva, the primitive North American bowfin.[18]
Snakeheads are considered valuable food fish. Called ca loc, ca qua, or ca chuoi in Vietnamese, it is prized in clay pot dishes and pickled preparations. Larger species, such as Channa striata, Channa maculata, and Parachanna obscura, are farmed in aquaculture.
In CSI: NY, snakeheads are placed in tequila bottles which are found by the team at the crime scenes in Season 7 Episode 4 ("Sangre Por Sangre").
In TV mockumentary series The Office webisode, "Blackmail", the character Creed Bratton is blamed for introducing the snakehead fish into the North American ecosystem.
In The Penguins of Madagascar episode "Snakehead!", a northern snakehead (wrongly identified by Kowalski as "the snakehead trout") invades a pond in Central Park and threatens to devour anything in its path. A mother duck and her ducklings seek the aid of the penguins from the Central Park Zoo (Skipper, Kowalski, Rico, and Private) to assess the situation. The penguins build a submarine to scour the pond, where they find the snakehead and destroy it by throwing a bottle of heavily-shaken-up soda down its throat (in a parody of Jaws), turning it into a large supply of sushi when the bottle explodes.
In the Animal Planet TV series River Monsters, Jeremy Wade shows a dramatization of a snakehead, "the fish from hell", stalking an unsuspecting baby and Chihuahua. With the help of a snakehead researcher, however, Wade shows that although it is capable of living outside of water and is able move on land, its weak pectoral muscles make movement difficult and render the snakehead an unlikely "stalker" on land. [19]
The snakehead was featured in three Sci-fi Channel original pictures entitled Snakehead Terror, Frankenfish, and Swarm of the Snakehead.
In the "Soprano Home Movies" episode of the HBO series The Sopranos, Bobby and Tony discuss snakeheads being found in the Adirondack area of New York when visiting Bobby's cottage. The fish had originally been mistaken as bowfins.