The world's longest-lived crocodile has tens of thousands of offspring! | Natural Trumpet

Welcome to the 72nd issue of the Nature Trumpet column. In the past half month, we have collected some natural news and research worth reading:

1) Humpback whales swim across three oceans, possibly looking for mates

2) The oldest crocodile celebrates its 124th birthday

3) Corals only reproduce with their neighbors

4) At what age do dogs start to age?

5) Sea otters make a difference by eating crabs

6) The most mysterious shovel-toothed beaked whale died of head injuries

The farthest distance a humpback whale has traveled

A male humpback whale has crossed three oceans in search of a mate, breaking the longest journey in the history of his species.

This humpback whale swam from the coast of Colombia in the eastern Pacific Ocean to the coast of Zanzibar in the southwestern Indian Ocean, spanning 13,000 kilometers. It was first discovered in the eastern Pacific Ocean in 2013, and nine years later, it was recognized in the Indian Ocean by the unique indentation on its tail. Coincidentally, when it was witnessed, it was in another humpback whale population, competing with a group of male whales for the opportunity to mate with females .

Researchers identified this humpback whale by its tail | References [1]

Researchers speculate that this male humpback whale traveled a long distance to find a mating partner - it swam across three oceans, and once it encountered other humpback whale populations, it would try to mate with the females in them. Another guess is that changes in climate and environment have led to changes in food distribution, which has also affected the humpback whale's route of action.

Generally speaking, humpback whales have a very uniform migration pattern. They move between feeding areas near the poles and breeding areas in the tropics, mainly in a north-south direction, which can be as long as 8,000 kilometers; but they rarely travel long distances in an east-west direction, and rarely mix with other groups . However, the actions of this male humpback whale show that the movement trajectories of humpback whales may be much more flexible than people previously thought.

The longest-lived crocodile

Let's wish this crocodile a happy 124th birthday!

Henry the Nile crocodile | Wild Charles / Facebook

His name is Henry, a Nile crocodile. He was captured in Botswana in 1903 and has lived in a conservation center in South Africa for nearly 40 years. It is currently believed that Nile crocodiles can live to about 70 years old in the wild, and even longer in captivity. Henry's exact birthday is unknown, but according to estimates by conservation center staff, he was probably born around 1900. He is the oldest crocodile known in the world , and everyone celebrates his birthday on December 16 every year.

Henry now weighs about 700 kilograms and is 5 meters long, making him a very powerful animal of his kind. Even at the age of 124, he is still going strong and showing no signs of physical decline. His emotional life is also very rich - in the past 40 years, he has given birth to more than 10,000 offspring with many partners .

Henry, a long-lived man with a happy heart and a plump body | Crocworld Conservation Centre / Facebook

Why can Henry live so long? Scientists speculate that the intestinal microbial flora of Nile crocodiles may have created a strong immune system, or the proteins in their blood may have strong antibacterial ability, which helps fight infection; captive life also allows Henry to not worry about eating and drinking, and reduces the risk of disease and accidents, which can also extend his life. However, it is not easy to study the reasons for the longevity of reptiles . Scientists have to tag them when they are young and then track them throughout their lives - but it is not certain who will live longer, them or the scientists who study them!

Corals only reproduce with their neighbors

As the saying goes, "a rabbit doesn't eat grass near its burrow," but corals can only eat grass near their burrows when they reproduce.

In a new study, scientists measured the distance between successfully fertilized coral individuals. They placed containers above 26 coral colonies, and the coral eggs would enter the containers, and once they entered, they could not escape; the containers moved with the water flow, and the coral sperm would drift into them to fertilize the eggs. After the containers drifted for an hour, scientists recorded the proportion of fertilized eggs of each type of coral in them and measured the distance between the corals.

Coral Spawning | Peter Mumby

The results showed that corals only reproduce with their neighbors . When the distance between corals is less than half a meter, their spawning is very synchronized, and the proportion of fertilized eggs can reach an average of 30%. However, when the distance between corals is about 10 meters, the proportion of fertilized eggs quickly drops below 10%; when the distance reaches 15-20 meters, fertilization is almost impossible. The weather will also affect the success rate of fertilization. If the wind speed is too fast, even if the corals are very close, the proportion of fertilized eggs is not high - the eggs will float away quickly, and the sperm can't catch up at all.

Reproducing only with neighbors is not good news for coral populations. Coral bleaching caused by global warming is killing corals one after another, and their density is also decreasing. Even if they want to reproduce, they may fail because they are too far away from other corals. Fortunately, this study provides a clear goal for coral restoration measures - to detect the density of corals and strive to restore the density to a critical value so that every coral has neighbors within reach.

Dog aging age

At what age is a dog considered old?

To find out, scientists recently analyzed the medical records of 832 older dogs. They found that, on average, dogs are described as senior by veterinarians at 12.5 years old . However, this time varies for different breeds: Small dogs (such as Jack Russell Terriers) do not begin to age until around 14 years old, but large dogs (such as Labradors) start to age around 12 years old.

A 15 and a half year old dog | Tsaag Valren / Wikimedia Commons

The study also looked at medical records to identify the top five health issues in older dogs :

1) Weight problems (35%): being overweight, underweight, or experiencing significant weight gain or loss.

2) Musculoskeletal system problems (33%): muscle stiffness, difficulty in movement, etc.

3) Dental problems (31%): ranging from common tartar accumulation to periodontal disease.

4) Skin problems (28%): swollen and painful skin, infection or severe hair loss.

5) Digestive system problems (22%): including vomiting, diarrhea, etc.

The aging rate of dogs varies from dog to dog, and health problems that gradually appear with age also require more attention from owners. Scientists will use this research result to develop an " Aging Dog Tool Kit ", which includes a self-checklist for owners to use: owners can refer to the self-checklist and seek medical attention in time if they find that their dogs have health problems related to aging, so that their dogs can live happier and longer.

Sea otters make great contributions again

Sea otters have been shown to help maintain the kelp forest ecosystem in the North Pacific by eating sea urchins, and now they are doing it again - this time by eating!

Common shore crabs, originally distributed in Europe, arrived on the West Coast of the United States in the 1980s and have since become one of the most destructive invasive species there . They eat young fish and crabs, severely hitting the fishing industry, affecting the entire coastline ecosystem and accelerating marsh erosion. In order to eliminate shore crabs and reduce the impact on the ecosystem, U.S. states have invested millions or even tens of millions of dollars and encouraged fishermen to catch more, but with little success.

Sea otters chew on a female shore crab full of crab eggs | Michael Yang

However, in the Elkhorn Slough, the only estuary in California with sea otters, something amazing has happened. Without human intervention, the sea otters' appetite has completely controlled the number of crabs . Sea otters have no blubber (the fat under the skin of marine mammals) to keep them warm, and they need to eat 25% of their body weight every day to support their energy consumption - and crabs are one of their favorite foods. Researchers at the sanctuary estimate that the sea otters here can eat 50,000 to 120,000 common shore crabs every year.

In decades of close monitoring, researchers have found that as the number of sea otters recovers, even as pollution increases, the rate of coastal erosion in the marshland has decreased by 80% to 90%, and some marshes are even expanding. This shows that when we protect key species in an ecosystem, they will make the entire ecosystem more stable and reduce a lot of economic losses to humans - and all this is free, all they do is happily chew crabs.

Let's say: Thank you sea otters! | Michael Yang

The most mysterious whale

We're finally learning a little more about the world's rarest and most mysterious whales.

This whale, Mesoplodon traversii, is the most mysterious and least understood of the large mammals in existence. In 1872, a jawbone of a shovel-toothed beaked whale was discovered and reported; since then, no one has ever seen a living shovel-toothed beaked whale in the sea, and only a few carcasses have been stranded on the beach, but most of them have rotted.

A male shovel-toothed beaked whale washed up on the beach in July | NZ Dept. of Conservation

In July this year, a 5-meter-long male shovel-toothed beaked whale washed up on a New Zealand beach. This is the first complete specimen ever . Recently, scientists dissected the specimen and found that it had a broken jaw and bruises on its head and neck, which may be the cause of its death.

Scientists also discovered that this shovel-toothed beaked whale actually has 9 stomach chambers (normal whales only have 4), which contain undigested squid and some parasites. Its upper jaw has degenerated teeth embedded in the gums, which allows us to glimpse the evolution of shovel-toothed beaked whales. Scientists also studied their structures related to feeding and vocalization, and measured and described their various organs. This can help us understand this mysterious whale and guess their behavioral habits and lifestyle when they were alive.

A specimen of a shovel-toothed beaked whale is being documented and analysed | NZ Dept. of Conservation

After the dissection, scientists will use 3D printing technology to replicate the bones and teeth of the shovel-toothed beaked whale and exhibit them in a museum so that more people can witness this rare specimen.

References

[1] https://royalsocietypublishing.org/doi/10.1098/rsos.241361

[2] https://www.livescience.com/animals/alligators-crocodiles/henry-the-giant-crocodile-who-has-sired-10-000-babies-celebrates-124th-birthday

[3] https://www.pnas.org/doi/10.1073/pnas.2418314121

[4] https://onlinelibrary.wiley.com/doi/10.1111/jsap.13809

[5] https://phys.org/news/2024-12-california-sea-otter-population-invasion.html

[6] https://phys.org/news/2024-12-zealand-scientists-specimen-world-rarest.html

Author: Cat Tun

Editor: Mai Mai