If you are friends, go to the toilet together! Chimpanzees do the same | Nature Trumpet

Welcome to the 75th issue of the Nature Trumpet column. In the past half month, we have collected the following natural news and research worth reading:

1) Alien algae invade, shrimps change into new clothes

2) Dolphins appear in California

3) Plants can deceive their neighbors by claiming to be dangerous

4) Due to ocean acidification, there are more female oysters

5) Like humans, chimps go to the bathroom together

6) As sea ice decreases, polar bears face a birth crisis

Shrimp's New Clothes

With the arrival of invasive species, the chameleon shrimp also put on new clothes.

Color-changing algae shrimp change color to blend in with the surrounding algae and avoid being discovered by predators. They can change into many colors to adapt to different algae, but it takes about a month for each color change.

Hippolyte varians can change colour to blend in with the algae around them | Martin Stevens

In a new study, scientists wanted to know how color-changing algae shrimp would respond to foreign algae. They placed color-changing algae shrimp in a Y-shaped tank and placed green or red native algae, as well as brown or pink foreign algae in the tank, allowing the shrimp to freely choose where to hide.

The results showed that the color-changing algae shrimp would quickly choose a type of algae and hide in it until the end of the experiment; but they would not tend to choose the local algae, but the one that was more conducive to their hiding . For example, the local green algae had flat leaves, while the foreign brown Sargassum had a complex shape, which was more conducive to their hiding from predators, so they would choose the latter - even if the latter did not match their color, they would not hesitate to spend energy and time to change into new clothes and become the same color as the foreign algae.

The Y-shaped experiment box (from this perspective, it looks like an inverted Y) has all the introduced algae on the left and the native algae on the right | Rafael Duarte

In the past 10 years, alien algae species from Asia and Australia have become increasingly numerous in European oceans and have gradually occupied the habitats of native algae, which is likely to directly affect the animals that rely on algae for survival. Fortunately, the color-changing algae shrimp has a strong ability to adapt and can still camouflage itself in the alien algae.

Dolphin Army

A large group of dolphins suddenly appeared near the coast of California, USA, with a total of more than 1,500 dolphins !

The dolphin army was discovered by a whale observation organization. They were looking for the whereabouts of gray whale migration, but unexpectedly found that their ship was almost surrounded by dolphins . Marine biologists flew drones into the air and saw a shocking scene: more than 1,500 Richter's dolphins gathered in the bay. They swam and jumped in the water, played beside the boat, and even hitched a ride on the bow, letting the waves created by the boat push them forward.

Dolphins appear in large numbers | Evan Brodsky / AP

This is not a common sight - dolphins are highly social animals and like to travel in groups, but the size of a group of dolphins is usually between 10 and 50. When food is plentiful, Richter's dolphins occasionally form large groups of several thousand, but they are mostly same-sex groups of similar age. In this dolphin gathering, adult dolphins and young dolphins mixed together, so scientists speculate that this is a group of several dolphins swimming south together , and humans happened to be lucky enough to witness their gathering.

Riess' dolphin (Grampus griseus) | Mike Baird / Wikimedia Commons

Richter's dolphins, also known as gray dolphins, are large dolphins that are mainly found in tropical to temperate waters around the world. They look "top-heavy" in appearance, with a relatively large front body and dorsal fin, while the back body gradually becomes thinner and narrower. They like to live in relatively deep waters, and the Monterey Bay where the large group of dolphins was discovered this time has submarine canyons, which is their ideal activity area.

Plants lie

Plants also eavesdrop, and use this to deceive each other.

Plants growing together are not as harmonious as they seem on the surface. There are undercurrents beneath the calm. They eavesdrop on each other - if their neighbors are attacked by herbivores or get sick, they will detect the chemical signals unconsciously emitted by the other party and predict the coming of danger. The closely connected underground fungal network can also provide information to plants: when a plant is attacked, the fungi will pass the information to other plants in the network. They have a symbiotic relationship with the plants. Only when the plants are safe can they have a long-term meal ticket.

Plants also have defenses against herbivores | Raul654. / Wikimedia Commons

When plants receive warnings of danger, they will prepare chemicals that are toxic to herbivores or make themselves unpalatable, but this requires a lot of energy, so plants will not enter defense mode unless necessary. Some plants will take advantage of this and set traps for their neighbors - they know that their neighbors are eavesdropping, but they deliberately lie about military intelligence, create false news that they are under attack, and induce their neighbors to waste precious resources to make defensive substances .

Fungal “intelligence network” allows plants to communicate with each other | References [3]

The intrigues between plants are also the result of evolution. They and their neighbors may need to compete for sunlight and nutrients in the soil. If competitors do useless work and waste more energy in vain, they can gain greater advantages and grab more resources.

Oyster sex

As oceans acidify, oyster sex ratios could face a major crisis.

Unlike mammals, which have sex chromosomes at fertilization, oysters rely on environmental factors to decide whether they grow into females or males. In a new study, scientists studied the effects of ocean acidification on the sex of oysters: they placed wild-collected oysters in tanks with neutral and slightly acidic pH values, and found that the proportion of female oyster offspring in tanks that simulated acidic oceans was significantly higher .

Ocean acidification affects sex ratios in oysters | References [4]

The effect of environmental pH on gender will continue to the next generation. Scientists moved the second generation of oysters in acidic water tanks to neutral water tanks, but the third generation of oysters born in neutral water tanks still had a higher proportion of females than in normal environments. This shows that even if the environmental pH returns to normal, the effects of ocean acidification will not disappear immediately.

Further research also found that in an acidic environment, genes involved in the development of female characteristics are activated, while genes involved in the development of male characteristics are turned off. As carbon dioxide levels continue to rise, the seawater absorbs carbon dioxide and becomes more acidic, and there will be more and more females in the offspring of oysters. Gender imbalance will lead to reproductive problems and ultimately affect the survival of the species.

Chimpanzees go to the toilet together

Like humans, chimpanzees like to go to the bathroom together.

Recently, scientists noticed that chimpanzees in zoos always urinate together, and they couldn't help but wonder: Could urination be contagious like yawning? To study this question, they observed 20 chimpanzees in the Kumamoto Nature Reserve in Japan and recorded more than 600 hours of data. The analysis found that when one chimpanzee in the group starts to urinate, the other chimpanzees are more likely to urinate together . Moreover, the closer the chimpanzees are, the more likely they are to be "infected" and urinate together; the lower the social status of the chimpanzees, the more likely they are to imitate their peers' urination.

Chimpanzees' behavior is influenced by their peers | Kumamoto Sanctuary

What are the benefits of peeing together? Scientists believe that on the one hand, contagious urination may strengthen social ties and make chimpanzees closer. On the other hand, urinating together can synchronize everyone's state and improve the cohesion of the social group, just like we march together during military training. Another possibility is that many chimpanzees peeing together can disperse the smell of urine, confuse predators, and reduce the risk of being discovered and tracked.

Humans, like chimpanzees, are influenced by the behavior of other companions in the group, such as yawning, shouting slogans, etc. Scientists believe that studying the contagious urination behavior of chimpanzees can help us understand the behavior of human ancestors and explore the origin and development of human society.

Peeing is as contagious as yawning | H. Zell / Wikimedia Commons

Polar bear birth rate declines

Polar bears are also experiencing a "declining birth rate crisis."

In a recent study, scientists built a model based on bioenergy calculations to predict changes in polar bear populations based on the energy polar bears get from prey and the energy they need to grow and reproduce. The model found that the decline in polar bear populations is directly related to the decline in sea ice caused by climate change . With the reduction in sea ice, polar bears find it difficult to hunt seals, so they can only starve on land, which reduces reproduction, and the survival rate of cubs will also be reduced due to lack of sufficient food. The polar bear population will inevitably shrink in the era of low birth rates.

Reduced sea ice makes seal hunting more difficult | Lysogeny / Wikimedia Commons

Scientists compared the model results with more than 40 years of monitoring data on polar bears and found a surprising consistency. Between 1979 and 2021, the polar bear population in western Hudson Bay decreased by nearly 50% , and the remaining polar bears have been losing weight, with adult females losing an average of 39 kilograms and one-year-old cubs losing 26 kilograms.

The birth rate also dropped significantly, and the number of cubs decreased by 11% ; at the same time, the cost of childbirth for polar bear mothers also increased - the cubs could not get enough food to grow and found it difficult to live independently, so mothers had to extend the time they took care of their children.

Polar bear mother with her cub | AWeith / Wikimedia Commons

Polar bears in western Hudson Bay are the southernmost polar bears and the first to face the loss of sea ice. They are like a weather vane for polar bears, and a sharp decline in their numbers means that other polar bears will also be unable to escape the disaster.

References

[1] https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2656.14217

[2] https://phys.org/news/2025-01-super-pod-dolphins-captured-drone.html

[3] https://www.pnas.org/doi/10.1073/pnas.2420701122

[4] https://pubs.acs.org/doi/10.1021/acs.est.4c07808

[5] https://www.cell.com/current-biology/abstract/S0960-9822(24)01594-X

[6] https://www.science.org/doi/10.1126/science.adp3752

Author: Cat Tun

Editor: Mai Mai

Title image source: Kumamoto Sanctuary

This article comes from GuokrNature (ID: GuokrNature)

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