Snakes are creatures that many people fear, and fear of snakes is rooted in our genes. According to research, in the prehistoric period of wind and food, primitive people realized that this creature was very deadly, and when encountered, they would quickly avoid it, and this sense of self-protection was passed down from generation to generation with genes, and modern people would not provoke it even if they were not afraid of snakes. Animals also know how to seek advantages and avoid harm, and will also avoid snakes when encountered, except for some animals that have anti-poison ability or eat snakes.
Nuwa makes up the heavens
The strong survival and reproduction ability of snakes was also worshipped by early humans, and the ancient myths of our country were Nüwa, Fuxi, Gonggong, Candle Dragon, etc. were all human-headed snake bodies, which were considered to be the most perfect forms at that time. In Western mythology, there is also medusa, a powerful snake-haired banshee.
At present, there are nearly 3,500 species of snakes in the world, including more than 650 species of venomous snakes, more than 200 species of venomous properties that cause human deaths, conservative estimates of the distribution of venomous snakes in the living area of about 3 billion people, even in the rapid development of anti-venom drugs, more than 100,000 people still die of snake venom every year. One of the phrases often heard in documentaries about snakes is that snakes are one of the most evolutionarily successful species, and they are all over the world. But this statement is clearly exaggerated.
<h1>Overview of the distribution of snakes</h1>
Snakes, as cold-blooded reptiles, are unable to regulate their body temperature on their own, so they are greatly affected by the environment. The most suitable temperature for snakes is 20-30 ° C, the suitable humidity is 50-70%, and the temperature and humidity are too high or too low will limit the survival of snakes. Tropical subtropical regions are the main distribution areas of snakes, such as South Asia, Southeast Asia, Africa and South America, China's southern snakes are more than the north, Liu Zongyuan's "Snake Catchers" was written in Yongzhou, Hunan.
The snake with the highest known distribution latitude is the Polar Northern Viper, which can live in the Arctic Circle. The highest distribution is the hot spring snake, which can live in the river valleys and hot springs of the Qinghai-Tibet Plateau, and a milk snake in South America can also live in the mountains at an altitude of about 3500 meters. But there are still large areas of the world without snakes.
The global distribution of snakes, dark red is a land snake, light red is a sea snake
As can be seen from the figure, there are three main types of snake-free areas:
Category I: high latitude areas - northern Eurasia, about 50° north of North America and islands including Greenland, the southernmost tip of South America, the Antarctic continent, Iceland, the Pacific and Indian Oceans at high latitudes, the Arctic Ocean, the Southern Ocean.
The second category: snake-free islands in low and middle latitudes - the two islands of New Zealand, the Hawaiian Islands, the Irish Islands, the islands.
Category III: Special Areas - Atlantic Ocean
The three types of regional reasons are different, and we will talk about them separately. The first type of high latitude area is because the temperature is too low to live for snakes, except for extremely hardy snakes like the Polar Viper, there are very few other cold-blooded reptiles. Let's talk about the second and third categories.
<h1>Why are there no snakes on the two islands of New Zealand and Hawaii? </h1>
As we all know, New Zealand is a famous snake-free country, because there has never been a snake in history, so there are many flightless ground-dwelling birds here, like the New Zealand national bird kiwi, the cute owl parrot. Next door to Australia is the "viper paradise", why is there no snake in New Zealand? Hawaii is tropical, why are there no snakes?
Kiwi birds with owl parrots
At present, the most mainstream theory is that the volcanic earthquakes on the islands of New Zealand and Hawaii are frequent, and the volcanic ash soil is rich in sulfur, which is not suitable for snakes. But I don't think this is the main reason, because the Malay Archipelago and the Japanese Archipelago are equally volcanic and earthquake-prone, and the soil is also rich in sulfur, why are there so many snakes in the Malay Archipelago and the Japanese Archipelago? I think the most important reason is the following.
It is far from the mainland, or it is too early to isolate from the mainland
The island of New Zealand separated from mainland Australia 85 million years ago and has had little contact since then, while the Japanese and Malay archipelagos have been connected to Eurasia many times in history, and various continental snakes have spread through a series of islands connected by land bridges. The Hawaiian Islands and New Zealand Islands are too far from the mainland, snakes can not enter, New Zealand lizards have not evolved into snakes, modern shipping has been prohibited after the development of snakes, natural factors and human control, to prevent the entry of snakes.
Hook blind snake
Originally, many isolated islands in Oceania were also snake-free, and later many snakes hid in boats to come to these islands, such as Guam, and the invading palm tree snakes almost ate the birds on the island. Hawaii is also a hundred dense, an earthworm-shaped hook blind snake hidden in a flower pot successfully landed in the Hawaiian Islands and gained a foothold. However, the blind snake is too small, non-toxic and harmless, and can be ignored. There are currently two snake-free states recognized in the United States – Hawaii and Alaska, strictly speaking, one because there are sea snakes in Hawaiian waters. Although there are no snakes in New Zealand, more terrible rats have been flooded.
<h1>Why aren't there snakes on the island of Ireland? </h1>
The island of Ireland is very close to the British Isle, the climate is warm and suitable, and there are several kinds of snakes living in the United Kingdom, why doesn't Ireland have it?
The current credible claim is that the island of Ireland only ended its ice age ten thousand years ago, and has been very cold before, and after the end of the ice age, it is blocked by the Irish Strait, and the snakes have not been able to enter the island of Ireland, and the grass snakes on the British Island seem to be foreign. Since there are no snakes on the island of Ireland, it is even less likely that iceland and Greenland will have snakes.
PS: The story about the Irish Ice Snake online is pure fiction.
<h1>There is no reason for the atlantic ocean snake</h1>
After talking about the snakes on land, let's talk about the sea snakes. Sea snakes evolved from snakes on land that returned to the ocean. Most are poisonous, with hook-billed sea snakes 80 times more toxic than sodium cyanide.
Sea snakes are mainly distributed in the Malay Archipelago and near Australia, where coral is overgrown, the water temperature is suitable, the rainfall is abundant, and the sea snake's drinking water comes from a layer of fresh water that stays on the surface of the sea after rain. But the Caribbean Sea in the Atlantic Ocean also meets these conditions, so why aren't there sea snakes?
Because sea snakes are native to the Indian and Pacific Oceans, only one of the four routes into the Atlantic Ocean can be done.
Article 1: From the Pacific Ocean through the Drake Channel in South America into the Atlantic Ocean – the latitude is too high, the water is too cold.
Article 2: From the Indian Ocean through south Africa's Cape of Good Hope into the Atlantic Ocean - the Benguela Cold Current is blocked, and the water temperature drops sharply, which does not work.
Article 3: From the Indian Ocean through the Red Sea-Suez Canal (opened in 1869) into the Mediterranean Sea - the Red Sea is too salinity, low precipitation, will dehydrate and die.
Article 4: From the central Pacific Ocean to the Caribbean Sea via the Panama Canal. This is the newest channel and the only one that works.
Divers kill lionfish
Since the opening of the Panama Canal in 1914, sea snakes have begun to appear in the Caribbean, but the number is small, it is difficult to stand firm, until now, the Caribbean Sea still has no stable sea snake population, with the increase of marine pollution, the future is even less likely. But another Pacific creature that has successfully invaded the Caribbean is the lionfish (scorpionfish).
Thus, the factors preventing snakes from occupying the globe are mainly climate and topography, as well as the shortcomings of cold-blooded reptiles themselves. Nature can really play with all living things at will, snakes that have existed for more than 100 million years can not escape the palm of nature's hands, how can we modern people with tens of thousands of years of history be arrogant?
I am Encyclopedia Qianxunjun, pay attention to nature, love nature, more wonderful content, please pay attention!