It started as a small fish fry, but after being released into the wild, it grew into a prehistoric behemoth | How scary is the alligator gar?

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Science Academy (ID:kexuedayuan)

In the past two days, every move of the "strange fish in the lake" has touched the hearts of millions of netizens.

Image source: Henan Metropolitan Channel

According to media reports, recently, a citizen of Pingdingshan City, Henan Province, found a large fish about 80 centimeters long with a pointed mouth and long teeth in Yunchan Lake in Central Park. The number of small fish in the lake began to decrease. The relevant departments identified this mysterious fish as an alligator gar, an invasive alien species.

Alligator gar, Image source: wikipedia

The appearance of the strange fish attracted great attention from local people. At first, a salvage team was organized to capture it but returned empty-handed. In desperation, they had to use water pumps to drain the water of Yunchan Lake and capture the "strange fish in the lake" . The live broadcast of the pumping attracted more than 30 million netizens to watch online.

On the evening of August 26, after a full month of capture, two cunning alligator gar were finally caught. The park management disposed of them harmlessly and arranged for personnel to carry out professional disinfection of the lake area.

Two fish caught in the net

Image source: CCTV News

What kind of strange fish is this that requires such a high price to catch?

Part 1

A prehistoric monster

Alligator Gar , scientifically known as Atractosteus spatula, belongs to the genus Atractosteus in the family Atractosteus of the order Agamidae. This ferocious fish has been roaming in the rivers of North America for tens of millions of years. Its history can be traced back to the early Cretaceous period more than 100 million years ago, making it a standard prehistoric "living fossil" .

Image source: Reference 1

This prehistoric fish is a real giant. Adults can usually reach 1.8 meters in length and weigh more than 45 kilograms. It is the largest of the seven existing gar species and one of the largest freshwater fish in North America. In 2011, an alligator gar caught in Mississippi, USA, is the largest individual on record. It is 2.572 meters long, weighs 148 kilograms, and has a girth of 120 centimeters . It is so big that it cannot be stewed in one pot.

On February 14, 2011, the largest alligator gar ever recorded was caught by fishermen.

Image source: fieldandstream.com

The most notable feature of the alligator gar is its protruding snout that looks like an alligator , with two rows of dagger-like teeth densely packed on its upper and lower jaws, which is where its name comes from. These sharp teeth are the alligator gar's weapon for hunting, and can easily pierce its prey, with explosive attack power.

Let’s test your eyesight and see if you can tell the difference between an alligator gar and an American alligator.

In addition to its impressive attack power, the alligator gar also has amazing defense . It is covered with a layer of diamond-shaped blue-gray enamel scales, which are basically the same as the hardest part of human bone - tooth enamel, with a Mohs hardness of 5, which is harder than ordinary steel . This layer of armor-like scales is difficult to penetrate in nature, making the alligator gar a "high-attack and high-blood" berserker, and it has almost no natural enemies in the rivers of North America.

The structure of the alligator gar scales. The green part in Figure b is the enamel.

Image source: Reference 3

Those whose names contain the word "crocodile" are not good people.

It is worth mentioning that the hard and crystal clear scales of the alligator gar have also attracted human attention. Early Native Americans used the scales of the alligator gar to make arrows or breastplates, and now a novel jewelry made of alligator gar scales is very popular in the southern United States.

Image source: wikipedia

Part 2

What does the killer in the water rely on to do whatever he wants?

Like most prehistoric fish, alligator gar have excellent adaptability , which is also their greatest asset for survival. Although alligator gar are freshwater fish, they live in tropical and subtropical rivers and lakes all year round, but they are not picky about salinity. They can be found from freshwater lakes to salty swamps, from river estuaries to bays .

Distribution of Alligator Gar in the United States

Image source: nas.er.usgs.gov

Another manifestation of the alligator gar's strong adaptability is its extremely special respiratory system. Unlike most of its close relatives, the alligator gar has evolved a thick, spongy and highly vascularized swim bladder that not only provides buoyancy, but also helps breathe air like a lung. This ensures that the alligator gar can not only inhabit water bodies that would suffocate most other fish, but can even survive out of water for a period of time !

The alligator gar's highly vascularized swim bladder has features similar to those of an amphibian lung.

Image source: Reference 4

Such a huge and adaptable creature has no natural enemies in its homeland of North America. Once it enters the natural waters of other countries, it will do whatever it wants, posing a great threat to fish, humans and the ecosystem.

The huge alligator gar may seem slow in action, but it is actually a very good hunter . When it ambushes its prey, its huge body floats quietly in the water, casting a shadow that covers the small fish below like a dark cloud. At the last moment, it will attack with its sharp teeth, and its torpedo-like body will quickly appear behind the prey and take it in one bite. Faced with such a powerful predator, our native fish can only take a beating .

Feel the lightning strike of the alligator gar as it hunts

Video source: wikipedia

This greedy carnivorous fish is not picky about food. It eats almost all living things in the water, including various fish, crustaceans, amphibians, reptiles, birds, small and medium-sized mammals and even carrion . A few alligator gar can easily eat up all the fish in a lake. In 2018, a fish farmer in Guangdong released 200,000 fish fry in a 60-acre fish pond, but only caught a few alligator gar and very few grass carp and silver carp. Each alligator gar was no less than 1.5 meters long.

In addition, although the alligator gar's sharp teeth can pierce prey, they have no chewing function . When eating, they can only rely on the movement of their head and jaw bones to generate strong suction to swallow prey . This has led to many researchers finding fishing gear and boat engine parts in their stomachs... This shows how greedy this fish is.

When the alligator gar eats, it can generate a strong suction force in about 42 milliseconds through the movement of its skull and jaw.

Image source: Reference 6

In fact, alligator gar is not only harmful to fish, shrimp, snails and clams in the water, but also to humans . On August 17, according to The Paper, a boy in Taizhou, Jiangsu was bitten on three fingers by a "strange fish" while playing by a community pool. The culprit was an alligator gar, and it was just a "little guy" with a body length of 70 cm and a weight of more than 10 kg . It is hard to imagine how aggressive an alligator gar that grows to 2 meters long would be if left alone...

Image source: The Paper

Alligator gar also plays a very harmful role in the ecosystem. Alligator gar not only has a very strong reproductive capacity, laying up to 150,000 eggs each time, but also has a lifespan of 26 to 50 years . If we are not careful enough to let them establish a stable population in China, it will undoubtedly be a disaster for the local ecological environment. What's more, the eggs of alligator gar are highly toxic, and animals or humans may be killed if they accidentally eat them. Once they rot, they are likely to pollute the water .

There is one point that everyone is concerned about that needs to be pointed out. Alligator gar: No! Good! Eat! Although their meat is edible, it is very woody and has a very rough taste . Americans simply call it a "junk" fish. Moreover, this fish is difficult to process and needs to be split with an axe. It is really not a qualified edible fish.

Alligator gar meat sold in American supermarkets

Image source: wikipedia

Part 3

Blindly releasing alien species = letting the tiger return to the mountains

Alligator gar have been found in China's southernmost Pearl River system, the Yangtze River Basin, and the northern water systems. How come this fish, a native North American fish, appears so frequently in our waters?

Image source: Cover News

The main reason is the indiscriminate release of animals .

The alligator gar, native to North America , was introduced as an ornamental fish because of its unique appearance and ferocious habits. A simple search on e-commerce platforms will reveal a lot of them, with prices as low as 10 yuan per fish. However, as the alligator gar grows in size and eats a lot, many fish lovers cannot afford to keep them at home, so they quietly "release" them into nearby rivers or lakes . The surrounding ecosystem suffers because the alligator gar will eat almost anything that lives in the water!

In fact, in addition to the alligator gar, there are many such alien aquatic species.

Since 2003, China has published four batches of "Lists of Alien Invasive Species in China" , which include alien aquatic organisms such as golden apple snails, bullfrogs, Procambarus clarkii, red-eared turtles, leopard catfish, red-bellied characins, Nile tilapia, mosquito fish, etc. There are even more alien aquatic organisms that are not included in the list , such as short-capped giant characins, undermouth catfish, rohu, Su's round-bellied fish, rainbow trout, largemouth bass, eye-spotted drum, channel catfish, and spoonbill sturgeon... They have all entered China's aquatic ecosystem due to their random release, bringing potential harm to local aquatic biodiversity and water ecological security.

At present, the country is promoting the governance and restoration of alien invasive species, and the list of alien invasive species is also being further updated . It is hoped that alien aquatic organisms that are extremely harmful, such as the alligator gar, will be included in the list as soon as possible.

This time, Henan spent a lot of manpower and resources to drain the water from the entire lake for a fish. The high cost is really frustrating. So, how can we prevent such incidents from happening again?

The best way to deal with alien species is to control them at the source and prevent them from entering . For example, legislation can be enacted as soon as possible to control the introduction and trading of alien invasive species; the census of alien invasive species can be accelerated to clarify the number, distribution range, and degree of harm of alien species in China; prevention and control guidelines can be formulated "by category and species" to clarify the key periods, key areas, and main measures for prevention and control.

Everyone who loves nature should raise their awareness of preventing biological invasions. If you are not sure whether your pets or plants are alien species, you should contact the relevant department for assessment and never release them blindly or dispose of them at will .

References:

[1] "Genome Compositional Organization in Gars Shows More Similarities to Mammals than to Other Ray-Finned Fish". Journal of Experimental Zoology Part B: Molecular and Developmental Evolution. Wiley. 328 (7): 607–619.

[2] "World Record Alligator Gar Pulled From Mississippi Lake Tangled in Fisherman's Net". Field & Stream. Retrieved April 19, 2014.

[3] Sherman, Vincent & Quan, Haocheng & Yang, Wen & Ritchie, Robert. (2016). A comparative study of piscine defense: The scales of Arapaima gigas, Latimeria chalumnae and Atractosteus spatula. Journal of the Mechanical Behavior of Biomedical Materials. 73. 10.1016/j.jmbbm.2016.10.001.

[4] Omar Ali, Ahmad & Baumgartner, Wes & Allen, Peter & Petrie-Hanson, Lora. (2017). Fine Structure of the Gas Bladder of Alligator Gar, Atractosteus spatula. International Journal of Toxicology and Environmental Science. 1. 10.15226/2572-3162/1/1/00105.

[5] http://environment.nationalgeographic.com/environment/freshwater/alligator-gar/

[6] Justin B. Lemberg, Neil H. Shubin, Mark W. Westneat. Feeding kinematics and morphology of the alligator gar (Atractosteus spatula, Lacépède, 1803). Journal of Morphology

[7] “The ferocious invasive species Alligator gar is suspected to have appeared in Guangzhou Baiyun Lake, posing a huge threat to native fishes”, Science and Technology Daily, 2019-02-15

[8] “Henan Ruzhou drains lake water to search for “strange fish”: how to prevent the invasion of alien species?”, Kankan News, 2022-08-24

Source: Science Institute

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