Running away after mating, is it to survive? | Nature Trumpet

Welcome to the seventh issue of the Nature Trumpet column. In the past half month, we have collected the following interesting natural research and news:

1) The tardigrade that uses a snail as a car

2) The little bat migrated 2,486 kilometers

3) Southern raccoons flashing in the city

4) The male spider ejects after mating

5) Extremely rare white humpback whale

6) Saltwater crocodile changes menu

Tardigrades hitchhike

The extremely small and super slow water bears (also known as tardigrades) have a unique way of moving around - riding on snails.

Tardigrades under a microscope | Philippe Garcelon / Wikimedia Commons

Scientists let snails crawl over water drops or moss sheets containing tardigrades, and found that when the snails passed by water drops, 28 tardigrades took the opportunity to attach themselves to the snails and hitch a ride; when they passed by moss, only 12 tardigrades got on the "snail car". Scientists also surrounded the tardigrades' living area with a silicone barrier, and found that only the tardigrades that got on the "snail car" could cross the barrier.

The wind can carry tardigrades to a distance of 1,000 kilometers, but this long-distance journey is very risky - they cannot predict whether the environment at the destination is suitable for survival. The "snail car" is different - snails and tardigrades both like to survive in humid environments. Riding on a snail, they are likely to reach a relatively friendly environment.

Milnesium inceptum, a snail that often lives in humid environments with tardigrades | References [1]

However, the "snail car" also has disadvantages. The snail's mucus is mainly water, but it dries very quickly. After drying, it will form a hard shell on the tardigrades, causing them to enter a "frozen" state, which takes a long time to recover and may even cause death.

Tardigrades in dried snail slime | References [1]

Bat migration

A small bat weighing less than 10 grams set a new record for bat migration distance - it flew 3,000 kilometers in 2 months.

This little guy | Viktor Stepanov

The female bat belongs to the Pipistrellus nathusii, which is only the size of a human finger and weighs only a few grams. At first, Russian researchers put a tracking ring on the female bat and released it back into the wild. 63 days later, people in a village near the French Alps recognized it based on the tracking ring. In the two months or so, it flew across Europe. The straight-line distance between the release site and the Alps is 2,486 kilometers, and the actual distance it has flown is likely to be more than 3,000 kilometers.

The shortest distance it spans is 2,486 kilometers. References [2]

Bats in Europe generally do not travel more than 1,000 kilometers during migration; even in tropical areas, bats only fly about 2,000 kilometers at most. Why did this bat fly so far? Researchers believe that it may have simply lost its way on its regular migration route, and took a long detour to arrive in France. If it did not get lost and flew along a planned route, it would mean that long-distance migration of bats is more common than people think.

There are more and more wind farms in Europe, and wind farms cause the death of hundreds of bats every year. Next, scientists will track more bats so that wind farms can avoid their migration routes and allow bats to reach their destination safely.

South American coati

In a densely populated city in Brazil, researchers photographed a southern coati (Nasua nasua) passing by.

That's it | References [3]

The southern raccoon is distributed in the forests of the southwestern United States and South America. It usually lives in trees and feeds on small invertebrates and fruits. Some of them also catch mice to eat. Due to the reduction of forest habitat, the population of southern raccoons has been declining in southern Brazil and the population is threatened.

Southern raccoon crossing the road | Bernard DUPONT / Wikimedia Commons

The southern raccoon that flashed by in the camera this time lives in the only green space left in this urban area. Before this, people had also found them rummaging through human garbage cans for food - southern raccoons are very adaptable. When they lost their original habitat, they began to learn to use the environment where humans live. The scientist who photographed this southern raccoon believes that urban green space is also important for wildlife protection. Maybe someday, those animals that can't find a home will regard this place as their only harbor.

Spider escape

After mating with a female, a male spider will eject itself from her body at a speed too fast for the human eye to detect - in order to escape!

The entire ejection process captured by a camera at 1500 frames per second | Zhang Shichang

The male of the spider, Philoponella prominens, is about 3 millimeters long, half the size of the female. Scientists noticed in the wild that after mating, the male always ejected so quickly that ordinary cameras could not record the details.

So they collected about 600 spiders, conducted 155 mating experiments, and filmed videos at 1,500 frames per second. They found that the spiders' ejection speed was quite amazing, up to 88 centimeters per second - equivalent to an adult jumping up and landing 530 meters away in 1 second, which is simply instant movement.

If you don't run fast enough, you will be eaten | Zhang Shichang

The huge explosive power of male spiders is due to the energy stored in their legs. They bounce so hard to survive. In the 155 mating experiments recorded, 97% of the males ejected after mating and survived; the only three males that failed to eject were all caught and eaten by the females.

This may be a way for females to select males. Males with healthier and stronger bodies can survive mating and have a chance to live to the next mating, and thus have more offspring.

White humpback whale

A rare white humpback whale was recently spotted off the Australian coastline.

This beluga whale is playing with dolphins | theguardian

At that time, a 16-year-old boy who was surfing noticed the whale's singing underwater. He quickly went home to get a drone with a camera and took pictures of the humpback whale and a group of dolphins playing. He found that ordinary humpback whales are black or dark gray, but when this humpback whale surfaced to breathe, its figure was white! After 20 minutes, the humpback whale disappeared, but it left the boy with an unforgettable experience of a lifetime.

Less than one in 10,000 humpback whales have albinism or the gene for albinism, and only one white humpback whale has been seen before. In 1991, the first male albino humpback whale was discovered in Queensland, Australia. It was called "Migaloo", which means "white guy" in the local Aboriginal language. Migaloo was all white, and the new humpback whale discovered this time is smaller than Migaloo and has gray spots on its body.

Migaloo the Whale / Twitter

Scientists believe that this white humpback whale is likely the son of Migaloo, who inherited his albinism and became the second white humpback whale in the same population. However, some scientists believe that this young humpback whale is not related to Migaloo, and that it is the leucism gene, not albinism, that causes its white skin. Migaloo, who suffers from albinism, cannot produce melanin, so his whole body is white, while the gray spots on this young humpback whale are consistent with the characteristics of the albinism gene - it affects the ability of each cell to produce melanin, but does not completely prevent the production of melanin.

To determine whether they are related, scientists still need to collect and compare their genetic information.

Saltwater crocodile changes menu

Over the past 50 years, the saltwater crocodiles' diet has changed dramatically - they have gone from eating fish to eating wild boars!

The saltwater crocodile (Crocodylus porosus) is the largest crocodile and the largest reptile in the world. Adult males can reach 7 meters in length. Due to extensive hunting, there were only a few thousand saltwater crocodiles left in the 1970s. Fortunately, their numbers are gradually recovering in northern Australia.

Crocodile crocodile | Bernard DUPONT / Wikimedia Commons

Researchers found 50-year-old saltwater crocodile skeleton specimens in the museum, and the isotopes in their bodies showed that the saltwater crocodiles at that time mainly fed on aquatic animals, such as fish and turtles. However, in the bones of modern saltwater crocodiles, scientists found that they lacked isotopes commonly found in marine predators because they had long since changed their menu to terrestrial animals, including wild boars and buffaloes.

This is a shocking result. Scientists speculate that when crocodiles entered the floodplain from the river mouth, the prey they could catch also changed - the floodplain was full of wild boars, and the fish became less, so they simply hunted wild boars to feed themselves.

Eurasian wild boar (Sus scrofa) | division, CSIRO / Wikimedia Commons

This change in menu can be regarded as a "self-rescue" for the saltwater crocodiles. The saltwater crocodile population, which was in danger at the time, was able to recover its population so quickly within 50 years precisely because of the change in food; and the increasing number of saltwater crocodiles can also inhibit the growth of pigs and bring a new balance to the ecosystem. This also inspired animal protectors that sufficient prey plays an indispensable role in the recovery of large carnivore populations.

References

[1]https://www.nature.com/articles/s41598-022-08265-2

[2]https://www.degruyter.com/document/doi/10.1515/mammalia-2021-0139/html

[3]https://neotropical.pensoft.net/article/81824/

[4]https://www.cell.com/current-biology/fulltext/S0960-9822(22)00485-7

[5]https://www.livescience.com/white-humpback-whale-spotted-in-australia

[6]https://royalsocietypublishing.org/doi/10.1098/rsbl.2021.0676

Author: Cat Tun

Editor: Mai Mai

This article comes from the Species Calendar, welcome to forward

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