The weather is too hot, so sea turtles can only hatch baby girls | Nature Trumpet

Welcome to the 15th issue of the Nature Trumpet column. In the past half month, we have collected the following interesting natural news and research:

1) Because the weather is too hot, all newborn sea turtles are girls

2) 150 critically endangered white-backed vultures were poisoned to death

3) The lake sturgeon that disappeared 50 years ago has finally repopulated

4) A fish with built-in antifreeze function that emits red and green fluorescence

5) Scientists chase moths with airplanes

6) The pig died, but its organs came back to life

The turtles are all female

Because the weather is too hot, all the sea turtles born in Florida, USA in the past four years are baby girls.

A newly hatched loggerhead sea turtle makes its way to the sea. | Hila Shaked / Wikimedia Commons

The sex of sea turtles is determined by the temperature during incubation. When the temperature is below 27.7 degrees Celsius, male sea turtles are born; when the temperature is above 31 degrees Celsius, females are hatched; if the temperature fluctuates between these two levels, a nest of baby sea turtles can contain both males and females. The past four summers have been the hottest summers on record in Florida; scientists have not found any newly hatched male sea turtles in these four years - there are five species of sea turtles in Florida, but no matter which species, all the turtles hatching on the beach are females.

It is not uncommon for 90% of sea turtles to be female. Even if the gender ratio is unbalanced, as long as there are males, the eggs can still be fertilized and the population can continue. However, if there are no males at all, once sea turtles become a "daughter country", they will face the risk of local extinction .

Loggerhead sea turtle eggs | US Fish and Wildlife Service

In addition to affecting the sex of baby turtles, temperature can also cause them to die in the eggs . Scientists have found that when the incubation temperature reaches 32.3°C, the number of embryos that die is 33% higher than when it is 29.7°C. Baby turtles hatched at high temperatures are also smaller , and they are more likely to become food for crabs on their way from the beach to the ocean. Continuous high temperatures year after year will be a disaster for turtles.

A newly hatched green sea turtle in Hawaii | Mark Sullivan / NOAA

Vulture poisoned

At least 150 critically endangered white-backed vultures were recently poisoned in Africa.

Last Thursday, about 100 white-backed vultures died after feeding on a poisoned buffalo carcass in South Africa's Kruger National Park, and the next day, more than 50 died in northern Botswana from the same cause.

White-backed vulture (Gyps africanus) feeding on a giraffe carcass | Bernard DUPONT from FRANCE / Wikimedia Commons

Animal protection organizations are investigating both incidents. They found that the bodies of the poisoned white-backed vultures were incomplete, and some parts may have been removed and resold by poachers .

It is not uncommon for vultures to be poisoned in the area. On the one hand, their heads can be used in traditional medicine and have commercial value. On the other hand, vultures feed on corpses. When poachers kill animals, vultures will come after hearing the news. Rangers can track poachers through their activities, which makes poachers hate these birds. In 2019, poachers poisoned vultures. At that time, 537 vultures died after eating the corpses of elephants poisoned by poachers, of which 468 were white-backed vultures.

White-backed vulture about to land | Charles J. Sharp / Wikimedia Commons

The white-backed vulture is listed as critically endangered in the IUCN Red List. In fact, there were millions of them in the 1980s, but their numbers have dropped sharply, probably due to eating animal carcasses with some veterinary drugs left on them. It is estimated that there are less than 6,000 mature individuals left in the world. The disappearance of more than 150 vultures is a devastating blow to this species. What is even more sad is that it is the breeding season now, and the birds that were poisoned are all parents. Without their parents, the baby vultures have become orphans and are likely to not survive.

Sturgeon breeding

Lake sturgeon, which became extinct in the Coosa River 50 years ago, are finally starting to reproduce!

A small lake sturgeon caught in the Coosa River | Matt Phillips

Lake sturgeons are a prehistoric fish that can reach more than 2 meters in length and weigh more than 100 kilograms. Females can live to be over 100 years old. They were originally killed by fishermen because they damaged fishing gear. Later, people discovered that their eggs could be made into caviar and their swim bladders could be made into fish maw, so they became commercially valuable and began to be fished in large quantities. In addition, their spawning route was blocked by dam construction, and in the 1970s, they completely disappeared from the Coosa River in the United States .

In 2002, people began collecting and hatching eggs from lake sturgeon populations in other waters , and released the cultivated fish into the Coosa River every year. However, it is not easy to restore them to reproduce in the wild. Female lake sturgeons need to grow to about 20 years old to reach sexual maturity, and they only spawn once every 4 to 5 years.

Adult lake sturgeon caught in Lake Coosa | University of Georgia

Surprisingly, just this year, three female lake sturgeons with black eggs were found in the Coosa River. This is the first time that sexually mature females have appeared since the release program began, indicating that the lake sturgeons are growing healthily in the river and may begin to reproduce.

Green antifreeze fish

Near Greenland, scientists discovered a fish with green fluorescent material flowing through its veins.

A juvenile finess-lined lionfish imaged under white light (top) and fluorescent light (bottom) | John Sparks and David Gruber

The fish, called the fine-striped lionfish (Liparis gibbus), is the first polar marine fish ever discovered to fluoresce. Its larvae even fluoresce both green and red, which is even more unusual for a single species.

Many marine fish have evolved bioluminescence, which means they can emit light to hide themselves or attract prey. However, the fluorescent protein of the lionfish needs to absorb external light of a specific wavelength to emit light , which does not seem to be useful in the long-term darkness of the Arctic. Researchers speculate that when there is light in the Arctic summer, bioluminescence may help them see their peers in the deep ocean.

A fine-striped lionfish in a Greenland glacier habitat | Peter Kragh

The researchers also found that the lionfish has two different types of antifreeze proteins , which have a similar effect to the antifreeze in car engines. These fish live in polar regions. Once their body fluids freeze, ice particles will form in their cells and they will not be able to survive. Antifreeze proteins will adhere to the surface of small ice particles and prevent them from growing into larger ice crystals. This is the life-saving secret of polar fish.

The level of antifreeze protein expression in the fine-striped lionfish is the highest among all known organisms . They produce large amounts of antifreeze proteins and release them into the blood, which circulates throughout the body.

Chasing moths in a plane

Scientists studying moths have come up with an alternative research method: chasing moths with airplanes!

Acherontia atropos | Dr. F. Nemos / Wikimedia Commons

They studied the Hercules-banded hawkmoth, a species known for its face-like patterns on its body. They attached radio transmitters weighing less than 0.3 grams to 14 hawkmoths and released them from Konstanz, Germany - and then the scientists flew behind the hawkmoths in a light aircraft to receive the radio signals .

Chasing moths with a plane | Max Planck Institute of Animal Behaviour

What is the migration journey of hawk moths like? Scientists were surprised to find that their flight path is straight , and they can even fly nearly 90 kilometers in a straight line in 4 hours, all the way to the Alps. Such straight flight is very rare among long-distance migratory animals.

What is even more surprising is that hawk moths can flexibly respond to different wind conditions . If the wind is in the same direction as their route, they will take advantage of the wind and fly forward; if they encounter headwinds or crosswinds, they will fly low to the ground and adjust their speed and trajectory to avoid deviating from their route.

Hawk moths were tracked from Konstanz, Germany, to the Alps in an almost straight flight path | Max Planck Institute of Animal Behaviour

In the past, people thought that insects migrated by following the wind. This study proves that insects have extraordinary navigation abilities, almost on par with birds. But what mechanism do they rely on to maintain their paths? This will be the next question scientists face.

Resurrection Organ

Once a person is declared dead, their organs and cells usually begin to decay rapidly - but researchers at Yale University have managed to stop this process by resurrecting organs from dead pigs and restoring their cell function.

Pexels/pixabay

Their secret is an artificial system called "OrganEx", which can recirculate the blood in the dead pigs and inject a specially formulated artificial solution into the blood to promote oxygen supply, anticoagulation, and inhibit cell death. One hour after the experimental pigs' hearts stopped beating, the researchers connected them to the OrganEx system for a six-hour perfusion treatment. The results showed that this treatment method successfully restored oxygen supply to tissues throughout the body, reduced tissue damage, and partially restored the cellular metabolic function of important organs such as the heart and liver. Under a microscope, the organ tissues that were processed after death also looked similar to healthy organs .

This technology is still far from truly reversing death, and the researchers have not restored the brain function of dead pigs. However, it may be applied to human organ donors in the future, allowing the organs to be transplanted to recover health after the donor's death.

References

[1] https://www.livescience.com/almost-all-florida-sea-turtles-female

[2] https://phys.org/news/2022-08-endangered-vultures-poisoned-death-southern.html

[3] https://phys.org/news/2022-08-prehistoric-fish-poised-comeback.html

[4]https://journals.sagepub.com/doi/10.1177/11769343221118347

[5] https://phys.org/news/2022-08-unusual-moths-migrate-thousands-kilometers.html

[6] https://www.nature.com/articles/d41586-022-02112-0

Author: Cat Tun, Window Knocking Rain

Editor: Mai Mai

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