Humans look for personality when choosing a partner, and so do seabirds! | Nature Trumpet

Welcome to the 44th issue of the Nature Trumpet column. In the past two weeks, we have collected the following natural news and research worth reading:

1) The killer whale that died after 53 years in captivity finally returned to its homeland

2) Seabirds also look for mates with similar personalities

3) Mammals actually glow

4) An iceberg hit a penguin sanctuary, but the penguins weren’t home

5) Dead killer whale swallowed 7 whole sea otters

6) Cats purr because their vocal cords have “padded”

Tokitae returns to hometown

Tokitae, the killer whale who died after 53 years in captivity, has finally returned home.

We have written about Tokitae's story before: After being captured in the waters off Washington State in 1970, she was sold to the Miami Seaquarium, where she was forced to live in a small tank and perform shows day after day. In March of this year, the aquarium planned to release her back into the wild, where she would have the opportunity to reunite with her still-living mother. However, before she could return home, Tokitae died on August 18 of kidney disease.

Tokitae performing in 1998 | Piotr Domaradzki / Wikipedia Commons

The Lummi tribe of the Native American tribe has always regarded killer whales as their relatives living in the water. Before Tokitae's death, Lummi elder Raynell Morris, commissioned by the late chief, went to the aquarium to visit Tokitae and prepare for her release. They gradually established a friendship, and Tokitae would splash water on Morris and play with her.

Unfortunately, it was Tokitae's ashes that the Lummi finally received. His ashes were placed in a white cedar box with an artist's painting of Tokitae's tail on top. The urn was wrapped with a flag from a ship sailing in Tokitae's home waters, with his real name in the Lummi language written on it - Sk'aliCh'elh-tenaut (which means daughter of Sk'aliCh'elh, the name of the killer whale family that originally lived in these waters). The Lummi sang, played drums and held a private holy water ceremony for Tokitae's ashes. They will escort the ashes in a Lummi police boat until it is scattered in Tokitae's home waters.

Lummi elder Morris sings and plays drums for Tokitae | Raynell Morris

With Tokitae's return, all of the southern resident killer whales captured in the 1970s have passed away , but Tokitae still has a companion who has lived with him at the aquarium for 40 years - a Pacific white-sided dolphin named Li'i. Recently, Li'i also left the Miami Seaquarium and was sent to SeaWorld San Antonio to reunite with his children, former mates and other species.

Li'i | SeaWorld San Antonio

Seabirds look for mates based on personality

Humans look at personality when choosing a partner, and so do seabirds.

A Kittiwake (Rissa tridactyla) couple | Dominic Sherony / Wikimedia Commons

A new study found that whether the personality of kittiwakes matches determines whether their marriage can last. The researchers first tested the boldness of each bird with plastic penguins, and then compared the personalities of each pair of seabirds. The results showed that the more similar the personalities of the couples were, the more successful they were in raising children and the stronger their marriages were ; on the contrary, if the personalities were very different, they were more likely to lose their children and were more likely to divorce.

Seabirds have a long lifespan, usually living into their 30s, and in most cases only have one partner for their entire life. Due to the harsh environment, in order to provide enough food and care for their children, neither the husband nor the wife can be a hands-off boss, but must work closely together and work hard together so that the children can grow up safely .

Baby birds wait in their nest for their parents to bring them food | Mike Pennington / Wikimedia Commons

When raising children together, the personality of the partner is crucial - the couple spends a long time at sea looking for food separately, and often makes decisions without the partner around. If the two birds have similar personalities, they can more easily predict the reaction of their partner, and the decisions they make are often more beneficial to both parties . For example, when they forage separately, they can predict the actions of their partner, so as to adjust their foraging itinerary and time, and return home to feed at the right time, so that the birds will not be hungry at home for a long time.

Raising children is important to maintaining a seabird couple's marriage. Finding a new mate takes time and energy, so seabirds don't divorce easily; but if a child dies due to personality incompatibility, the couple's relationship is likely to break down.

Mammal luminescence

What? Mammals generally fluoresce?

The scientists found that all mammals (including humans) have fluorescent teeth , many of them also have fluorescent nails, and 86% of the 125 mammal species they studied also have fluorescent fur.

Echidna under ultraviolet light | Western Australian Museum

Fluorescence refers to the ability to glow under ultraviolet light - the skin or hair of an animal absorbs the ultraviolet light and re-emit it as visible light. Self-fluorescence is more common in nocturnal animals and is more intense; aquatic animals fluoresce less than terrestrial animals. Some animals fluoresce even though they are active during the day, such as a zebra's stripes, where the white part fluoresces but the black part does not.

Zebra fur under ultraviolet light | References [3]

Dolphins are aquatic mammals, only their teeth can fluoresce | References [3]

What is the purpose of fluorescence? Researchers do not have a definite answer yet. They speculate that fluorescence can make animals look brighter, which is helpful for identifying each other , which is very useful for animals that are active at night; some animals only glow on their abdomens, perhaps to make it easier for their own kind to recognize them, but predators just can't see it. But in some species, fluorescence may not have any practical purpose, but is just a byproduct of evolution. For example, white hair is naturally fluorescent due to its structural characteristics.

Iceberg hits penguin sanctuary

The iceberg hit the penguins' home and almost killed the whole family - fortunately, the penguins were not at home.

This huge iceberg is located in Antarctica, about 72 kilometers long and 20 kilometers wide, much larger than China's Zhoushan Island. It broke off from its parent iceberg in 2021 and was named D-30A. It has been drifting slowly since then until it recently hit Clarence Island violently .

Satellite image of the D-30A as it moves over the edge of Clarence Island | NASA Earth Observatory/Wanmei Liang

Clarence Island is a breeding ground for chinstrap penguins , with 100,000 breeding pairs coming here every winter to breed. Fortunately, the timing of the iceberg hitting the island was just right, and now the island is empty, and it will take a few months for the penguins to return. If the penguins were on the island, the impact would have been a major disaster for the ecosystem.

The antarctic penguin (Pygoscelis antarcticus), also known as the chinstrap penguin, is very vivid | Diego Tirira / Wikimedia Commons

However, this does not mean that the penguins have escaped. When an iceberg collides with an island, it is possible that it will get stuck on the surrounding seabed. The huge amount of ice will block the foraging passage of marine animals, change the salinity and temperature of the surrounding seawater, and destroy the ecosystem on the seabed. Fortunately, there is a deep steep slope on the east side of Clarence Island that allows the iceberg to pass directly, so NASA scientists estimate that D-30A should not be trapped here for too long .

According to satellite monitoring, D-30A is now moving towards the Drake Passage. Drake has a nickname called "Glacier Alley". When the glaciers reach here, they will be swept into the ocean currents, reach warm waters, and gradually die.

Killer whale swallows sea otter

In 2020, a killer whale was stranded on a beach in Russia. An autopsy found that its body was filled with seven complete sea otters ! Recently, scientists published a study on this bizarre killer whale.

A dead killer whale and a sea otter in its stomach | Sergey V. Fomin

The killer whale not only had six intact sea otters in its stomach, but also had one stuck between its mouth and esophagus. Researchers speculated that the sea otter stuck in its esophagus might be the direct cause of its death . The total weight of these sea otters was 117 kilograms, and there were also 256 cephalopod beaks in its stomach.

This is indeed a strange thing. On the one hand, sea otters are generally not included in the diet of killer whales; on the other hand, killer whales are notoriously picky eaters . When hunting seals, dolphins and other animals, they will tear the animals apart and only eat the parts with the best taste and nutrition (such as the liver), and usually will not swallow the whole prey in one gulp. Moreover, an adult sea otter is more than 1 meter long, so it is not easy to swallow it whole. Perhaps the killer whale was starving at the time, so it devoured it so voraciously.

Sea Otter | Marshal Hedin/Wikimedia Commons

Based on DNA, the researchers confirmed that the dead female killer whale was a transit killer whale with a wide range of activities. They believe that this group of killer whales may have learned the skills of hunting sea otters from elsewhere , which also explains why the number of sea otters between the Aleutian Islands and the Gulf of Alaska has been declining during this period - this area is the activity area of ​​transit killer whales, and the sea otters may have entered the stomachs of killer whales.

Cat vocal cord pads

Does your cat always make a purring sound , like a little engine?

Previous studies have shown that cats' purring is produced by the contraction and relaxation of the vocal cord muscles, which requires the brain to continuously control the vocal cord muscles through nerves. However, the latest research has found that the truth is completely the opposite - when cats purr, they do not need neural control at all, and do not even need repeated vocal cord muscle contraction at all .

Kittens purr when they enjoy a massage | Cat Swallow

The secret lies in a special "pad" in the cat's vocal cords - a piece of connective tissue that can be up to 4 mm in diameter. This pad can reduce the Young's modulus of the innermost part of the vocal cords (in simple terms, Young's modulus determines how much elastic material will deform when it is stressed; within limits, the smaller the Young's modulus, the greater the deformation), so that a small driving pressure can make the vocal cords vibrate at a low frequency, without the need for neural input or active muscle contraction.

Location of the meat pad | References [6]

Cats can easily produce low-frequency purring sounds of 25-30 Hz. The lowest frequency sound that humans can produce is about 80 Hz, so cats win again.

References

[1] https://phys.org/news/2023-09-ashes-orca-tokitae-home-death.html

[2] https://onlinelibrary.wiley.com/doi/10.1111/eth.13405

[3] https://royalsocietypublishing.org/doi/10.1098/rsos.230325

[4] https://www.livescience.com/planet-earth/antarctica/45-mile-long-iceberg-slams-into-penguin-refuge-in-antarctica-almost-causing-ecological-disaster

[5] https://www.aquaticmammalsjournal.org/article/sea-otters-enhydra-lutris-found-in-the-stomach-of-a-stranded-killer-whale-orcinus-orca-in-the-commander-islands-western-north-pacific/

[6] https://www.cell.com/current-biology/fulltext/S0960-9822(23)01230-7

Author: Cat Tun

Editor: Mai Mai

This article comes from GuokrNature (ID: GuokrNature)