How to measure the height of a tiger? First make a curry-flavored ruler | Natural Trumpet

Welcome to the 42nd issue of the Nature Trumpet column. In the past two weeks, we have collected the following natural news and research worth reading:

1) London Zoo weigh-in day, 14,000 animals weighed in

2) Dolphins have their own hospital, where they can recover and return to the sea

3) Sea chameleons can change color according to the environment after death

4) African wild donkeys welcome new cubs, a hope for the critically endangered species

5) A pure-colored giraffe was born, without any spots

6) Penguins with too much melanin have black front and back

Weigh-in Day at London Zoo

It’s the annual weigh-in day at London Zoo !

Meerkat: Look how much I weigh, show me now! | James Manning / PA

London Zoo has more than 14,000 animals . Over the course of several days, all animals, from giraffes to stick insects, have to be weighed in turn; some also have their height and waist measured to see if they have grown taller, gained weight, or are pregnant. These measurements are part of the health check .

Humboldt penguins: We’ve already lined up, why haven’t we given them food yet? | Kirsty Wigglesworth / AP

Getting animals to step on the scale is not an easy task , so keepers used all sorts of tricks: using snacks to trick meerkats onto the scale, or putting a scale in the area where Humboldt penguins eat breakfast, so that the little penguins can step on it to get their weight measured while waiting in line. The most difficult ones are squirrel monkeys, which are easy to trick onto the scale, but once they get on, they won't leave.

Squirrel monkey: It's fun here, I won't leave anymore | AFP

This year, the heaviest animal in the zoo is Maggie the giraffe , which weighs 750 kilograms. The smallest is a leaf-cutter ant , which weighs only 5 milligrams. Leaf-cutter ants are so small that the keepers can only weigh the entire ant colony and then calculate the weight of each small ant .

Sumatran tiger: I grew taller this year! (The measuring stick is curry-flavored) | Kirsty Wigglesworth / AP

The keepers have recorded all the data, and they will also upload the measurement results to the animal information management system and share the data with zoos around the world so that all zoos can understand the health information of endangered animals .

Dolphin Hospital

In Cape Cod, Massachusetts, USA, people built a special hospital for dolphins!

Cape Cod's unique topography makes it the most common place in the world for marine mammal strandings - in the past five years alone, more than 400 dolphins, porpoises and whales have been stranded on local beaches .

Cape Cod looks like a hook sticking out into the sea, making it difficult for dolphins to navigate and prone to getting stranded | NASA

Previously, rescuers could only take care of stranded marine animals on site and then immediately release them back into the ocean. However, for animals that are dehydrated and in shock, they need more rest to recover . With this dedicated hospital, they finally have a transit place where they can receive treatment.

A stranded dolphin with a wet cloth underneath can slow its heart rate and prevent it from going into cardiac arrest | Julia Cumes / AP

The newly built dolphin hospital is about 400 square meters, including a 170 square meter rehabilitation area, 2 treatment pools and a veterinary laboratory. There are 4 full-time staff members who take care of dolphins around the clock. This hospital is not a long-term animal rehabilitation center, but an intensive care unit for dolphins, providing temporary rest and treatment for stranded dolphins, with the goal of releasing them back to the ocean within 4 days .

The public can also see the rescued dolphins through dolphin monitors in the hospital's specially built education center, but cannot directly contact them.

Sea chameleon

The long-spined wrasse is the chameleon of the sea , fluidly changing its color to match its surroundings—even after death .

They are also called hoghead fish because they use their snouts to dig around on the seafloor when feeding, much like a pig. | Albert Kok / Wikimedia Commons

But how do they see the color changes in their environment when their brains are dead ? Recently, scientists have discovered the answer: they "see" through their skin.

Under the pigment cells in the skin of this fish are special photosensitive cells containing SWS1 opsin that is particularly sensitive to blue light (this protein is also found in the human retina). The ocean is blue, and the pigment cells are equivalent to a filter , so the opsin can not only receive changes in the light of the surrounding environment, but also sense the color of the skin - the redder the skin color, the less blue light enters the opsin. The wrasse can thus perfectly match the color of itself and the surrounding environment, and can even switch between 3 colors in one second .

Perfect camouflage | Bernard DUPONT / Wikimedia Commons

The long-spined wrasse is a master of transformation - not only can they change colour, but they can also change sex . They are born female and transform into males at a certain age.

African wild donkey baby

One of the world's most endangered animals, the African wild ass , has welcomed a new calf.

Newborn African wild donkey | Marwell Zoo

The African wild ass looks like a donkey with zebra legs and is considered the ancestor of the donkeys that humans domesticate today . They originally lived in the deserts of Eritrea, Ethiopia and Somalia, and there are only a few hundred of them left in the wild. They have been listed as critically endangered on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species.

The cub is a male and was born at Marwell Zoo in the UK. It is the result of several generations of breeding in the zoo . Its mother Nadifa was also born in the zoo 16 years ago, and its grandparents have lived here for 30 years.

After the cub was born, the staff temporarily removed its father from the enclosure to give it enough time to build a relationship with its mother. The zoo hopes that careful breeding and feeding can bring new hope to this species .

Solid color giraffe

A reticulated giraffe was born in a zoo in Tennessee, USA, but it does not have reticulations, but is solid color !

The last time a pure-colored giraffe appeared was in Tokyo's Ueno Zoo in 1972. Therefore, this rare baby giraffe immediately became an Internet celebrity after its birth , not only tripling the zoo's visitor flow, but also many people participating in the zoo's online vote to name it.

Solid-colored baby giraffe and its patterned mother | Brights Zoo

The baby giraffe's mother, Shenna, is a 9-year-old reticulated giraffe. Her three previous baby giraffes were all spotted. Veterinarians believe that a mutation in one or more genes may have caused the baby giraffe's special color . It weighed 86 kilograms when it was born and grew to 1.8 meters in just a few weeks. Except for the lack of spots, it is currently healthy and normal.

Giraffe in the wild | Axel Tschentscher / Wikimedia Commons

The spots on a giraffe have two functions. One is to camouflage itself in the wild and avoid attacks from predators . Fortunately, the baby giraffe is in the zoo and is not in danger of being hunted. The second is to help dissipate heat . There is a complex network of blood vessels under the spots. When the weather is too hot, more blood will be transported under the skin, thereby achieving the effect of heat dissipation and cooling. Veterinarians have not yet concluded whether this solid-colored giraffe will have trouble dissipating heat. They think they can take a picture of it with a thermal imager. Maybe the subcutaneous blood vessels are still distributed in spots, but we can't see them with the naked eye .

Melanin Penguin

In addition to solid-colored giraffes, scientists recently discovered a penguin that is almost completely black - its front is almost as black as its back.

This is the one on the left | Reference [6]

This is a Gentoo penguin . Its chest and abdomen should have been pure white, but due to excessive melanin , some feathers turned black, and finally became a "spotted sweater". The coloring of feathers is achieved through two pigments, carotenoids and melanin. Scientists speculate that it may be a pigment imbalance caused by genetic mutations , which ultimately resulted in such a one-in-a-million appearance.

Generally, the back of a Gentoo penguin is black , and the front is white except for the head. Studies have shown that the black and white color of penguins can confuse predators in the water and reduce the possibility of them being eaten - if you look down from above, the black back of the penguin can blend into the dark ocean; when you look up from below, predators cannot distinguish their white bellies from the sky above.

Emperor penguins have been spotted all black before | BBC

Fortunately, scientists have not found that the black front makes penguins more vulnerable to predators , and the little penguin gets along well with other penguins in the group and is not excluded. However, because its gender is uncertain, scientists cannot be sure whether this unique appearance will affect its search for a partner .

References

[1] https://phys.org/news/2023-08-london-zoo-animals-tarantulas-tigers.html

[2]https://www.bostonherald.com/2023/08/27/as-cape-cod-sees-the-most-dolphin-strandings-a-new-rescue-center-opens-in-orleans/

[3] https://www.nature.com/articles/s41467-023-40166-4

[4]https://www.livescience.com/animals/land-mammals/critically-endangered-donkey-with-stripy-zebra-legs-born-in-uk-zoo

[5]https://www.nationalgeographic.com/animals/article/rare-spotless-giraffe-born-us-zoo

[6]https://link.springer.com/article/10.1007/s00300-023-03190-0

Author: Cat Tun

Editor: Mai Mai

Kirsty Wigglesworth/AP