They have become notorious as invasive species, to the extent of becoming a byword for monster in popular culture.
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[edit]Description
The size of the snakehead species differs greatly. "Dwarf snakeheads" like 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. When adult, 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. They can grow to around 1 meter in length.
[edit]History
Channidae are well-represented in the fossil record and known from numerous specimens. Research indicates that snakeheads likely originated in the south Himalayan region of Indian subcontinent (modern-day Northern India and Eastern Pakistan) at least 50 million years ago, 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]
[edit]Ecological concerns
Snakeheads can become invasive species and cause ecological damage because they are top-level predators, meaning that 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[citation needed] as they have become an invasive species.
[edit]Intentional introductions
Humans have been introducing snakeheads to non-indigenous waters for over 100 years. In parts of Asia and Africa, the snakehead is considered a valuable food fish and is produced in aquacultures. Due to this fact it was introduced either on purpose (fisheries motivation) or by ignorance (as was the case in Crofton). Some examples of the introduction of snakeheads to non-indigeneous waters include:
- Channa maculata was introduced to Madagascar and to Hawaii around the end of the 19th century. It can still be found there today.
- Channa striata was introduced to islands east of the Wallace line by governmental programs in the later half of the 20th century. In Fiji, the introduction failed.
- Channa asiatica, which is native to southern China, was introduced to Taiwan and to southern Japan; the origin and reason of the introduction is unknown.
- Channa argus, which is native to northern China (Amur River), was introduced to Central Asia (Kazakhstan, Turkmenistan, Uzbekistan). It was introduced to Japan about 100 years ago due to fisheries motivations. Its introduction to Czechoslovakia by the government in the 1960s failed due to cold winters.
[edit]Reported sightings
[edit]In the US
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 non-established specimens have been found in Wawayanda, New York,[8] two ponds outside 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 dollars 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 9, 2004 while fishing from Lake Michigan at Burnham Harbor in Chicago, Illinois. According to the United States Environmental Protection Agency, snakeheads have also been spotted in California, Florida, Hawaii, Maine,Maryland, Massachusetts and Rhode Island.[10]
[edit]Elsewhere
A reported catch from the Welland Canal in Canada turned out to be a misidentified specimen of Amia calva, the primitive North Americanbowfin.[12]
[edit]As food
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 like Channa striata, Channa maculata, and Parachanna obscura are farmed in aquaculture.
[edit]In popular culture
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In TV mockumentary series The Office webisode Blackmail, the character of Creed Bratton is blamed for introducing the Snakehead fish into the North American ecosystem.
On the TV series River Monsters,[13] Jeremy Wade shows a dramatization of a snakehead stalking an unsuspecting baby and chihuahua. All hell breaks loose.
In The Penguins of Madagascar episode "Snakehead!", a species of snakehead 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, turning it into a large supply of sushi when the bottle explodes.
The snakehead was featured in a Sci-fi Channel original picture entitled Snakehead Terror
In the HBO series The Sopranos, Bobby and Tony discuss Snakeheads being found in the Adirondack area of New York when visiting Bobby's cottage.
In CSI: New York, snakeheads are placed in tequila bottles which are found by the team at the crime scenes in Season 7 Episode 4 (Sangre Por Sangre).
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