How does the Yangtze River dolphin, known as the "smiling angel", give birth to babies?

When it comes to whales and dolphins, many people think that they live in the ocean and are hard to see. But in fact, there are also many whales and dolphins living in rivers, lakes and ponds.

The Yangtze River dolphin is the only freshwater cetacean that can be seen in the wild in my country. It is small and round with a "smiling face". When it smiles at you, you should smile back at it.

Hi~~

Image source see watermark

But behind their cute "smiles" is a precarious fate - there are only about a thousand Yangtze finless porpoises left, which is even fewer than the number of giant pandas.

To visit these endangered Yangtze River elves, the "Bowu" editorial team came to the Institute of Hydrobiology, Chinese Academy of Sciences in Hubei Province.

Image source: Yangtze River Daily

01

Smiling angel, can also kill with tilted head

The "Baji Dolphin Hall" (hereinafter referred to as the "Dolphin Hall") of the Chinese Academy of Sciences is located in a secluded corner of the East Lake in Wuhan. This dolphin hall is the only place in the world dedicated to the breeding, reproduction and protection of freshwater cetaceans. On the one hand, it conducts scientific research, and on the other hand, it is open to the public for a limited time as the "Wuhan Science Education Base".

The dolphin house consists of two buildings: the main breeding hall and the breeding hall. From a distance, they look like two large round tents.

The main breeding hall and breeding hall of the dolphin house

Although it is called the "Baiji Dolphin Hall", the hall actually houses Yangtze River dolphins. Walking into the main hall, you will see a large pool in front of you. Occasionally, Yangtze River dolphins will emerge from the water with their heads and backs, and make a "puff" breathing sound. They have discovered that there are strange visitors, and they frequently raise their heads above the water to look around, and they seem to be very curious.

The Baiji Dolphin House of the Institute of Aquatic Biology was built in 1980. A rescued Baiji dolphin named Qiqi moved in right after the house was built and lived there for 22 years. After Qiqi died in 2002, no Baiji dolphins were found in the wild. At this time, the Yangtze River dolphins, which were once numerous, were also endangered, so the dolphin house was changed to study Yangtze River dolphins.

The keeper, Mr. Shu Guilin, received us. He took us to the underground floor, which was equivalent to the "exhibition hall" with several huge observation windows on the wall like an aquarium. As soon as we stood in front of the observation window, four finless porpoises swam over and looked at us face to face through the glass.

Compared to the dolphins I've seen before, they are much smaller, with a grayish-blue body and no patterns, a round head, and no pointed mouth like a dolphin. The most impressive thing is that the corners of their mouths are slightly upturned, as if they are smiling! No wonder some people call the Yangtze River dolphin the "smiling angel" in the water.

The Yangtze River porpoise has its mouth corners raised, making it look like it is smiling, so it is called the "smiling angel".

In fact, the Yangtze River dolphin, like other cetaceans, has no expression. This is just humans judging dolphins by their own standards.

Wow!

Image source: Internet

"Most of the time, the finless porpoises can only see the five people working in the dolphin house, so they are a little excited to see strangers." They hovered in front of the observation window repeatedly, swimming from left to right, and then from right to left, and sometimes even head down and tail up, "performing" underwater free fall upside down in front of the window - but from beginning to end, their eyes were always looking at us outside the window.

The neck of the Yangtze River dolphin is obviously more flexible than that of ordinary dolphins, and it can make a slight head-twisting movement. Faced with the "head-tilting killing" attack, everyone had to surrender and exclaimed "too cute!"

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02

A newbie in holding breath, but quite good at it

We watched the finless porpoises swimming around in front of the observation window and found that their breathing frequency was quite high. They had to float to the surface to breathe after swimming underwater for only a short time.

Teacher Shu told us that although the finless porpoise is an aquatic animal, its diving ability is not very strong. It often comes to the surface to breathe every ten seconds. After taking a few high-frequency breaths, it will dive for tens of seconds. On average, the finless porpoise will surface to breathe 2 to 3 times per minute, which means that the time they hold their breath in the water is not as long as that of trained divers. If a finless porpoise accidentally enters a fishing net in the wild, it will drown and die after more than 3 minutes.

Sometimes the porpoises come to the surface and spit water for fun.

Image source: Internet

The porpoises also blow bubbles in the water.

Image source: Internet

In order to prevent the finless porpoises from getting too bored, the dolphin house prepared small balls for them to play with.

Next, Mr. Shu introduced the four finless porpoises in the pool. Two adult female porpoises: Fukui and Yangyang, and two juvenile porpoises: YYC and Ebo. Yangyang is the mother of YYC, and YYC is just a temporary code name, which means "Yang Yang's calf", that is, Yangyang's cub.

"The most active one is E-Bo, and the one that always follows its mother is YYC." The finless porpoises are blue-gray in color with no patterns, and can only be distinguished by their body shape and some subtle differences. We found that although YYC is slightly shorter in length, it still seems to have "baby fat" and is more robust than the two adult female porpoises.

Lively and cute little fat boy

Photographed by: Wu Haifeng

The baby finless porpoise is weaned at about 6 months old, starts to live independently at 2 years old, and becomes sexually mature at 5 years old. Perhaps because of the stable life in the dolphin house, the 1-year-old YYC seems to be a bit "childish". Although he has been weaned for a long time, he still touches his mother's belly with his head from time to time. This is the standard action of the finless porpoise cubs to ask for milk. When swimming, YYC is almost inseparable from his mother, always hiding behind his mother's side, and is a clingy baby.

When the baby dolphin touches the mother dolphin's breast cleft, it will stimulate the mother dolphin to secrete milk. The baby dolphin rolls its tongue into a cone shape and uses the vacuum to suck the milk. Image source: Internet

There are two adult male dolphins in the dolphin house. Because it is not the breeding season, they are kept in a pool in the breeding hall next to it. The "parent-child dormitory" is separated from the "male dormitory" to simulate their natural state.

In the wild, finless porpoises usually form small groups of 2 to 5, but sometimes there are dozens or even hundreds of them. Males leave their birth group at around 2 years old, and either form a "bachelor group" with other young males or live with another male. Females generally stay with their mothers throughout their lives.

In June this year, several porpoises were found playing in the Nanjing section of the Yangtze River.

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03

Birth Horror

In order not to disturb the finless porpoises, we stayed in the dolphin house for only 30 minutes before Teacher Shu "asked" us to leave. Although the finless porpoises are very curious, they are very timid and easily frightened. Previously, a finless porpoise choked on water when being fed because it was frightened by the sound of a camera shutter. Later, during an interview at the Tian'ezhou Nature Reserve, we learned that an adult finless porpoise was frightened to death by lightning.

Keepers usually conduct "behavioral training" on the finless porpoises. This is not for performance, but to build enough trust with them to facilitate daily feeding and physical examinations.

When the finless porpoise opens its mouth to eat fish, it reveals a mouthful of small teeth - not the conical fangs of dolphins (bottlenose dolphins), but flat shovel-shaped ones that look a bit like human teeth. The finless porpoise's food is mainly small fish such as mullet and crucian carp. It is fed four times a day at about 8 am, 11 am, 4 pm and 8 pm. Each porpoise eats about 4 kilograms of food per day.

In the meeting room of the Dolphin House, we met Dr. Hao Yujiang, who specializes in studying finless porpoises. He said that over the years, the finless porpoises in the Dolphin House have provided a lot of valuable information, which has greatly deepened our understanding of this animal.

Now we know that the finless porpoise is not a "high-yield" animal. The pregnancy period is as long as 12 months, and only one baby is born each time. Even if a mother porpoise occasionally conceives twins, it will abort halfway. This may be related to the large size of the finless porpoise fetus - the adult body length of the finless porpoise is only about 1.5 meters, while the newborn is 70 centimeters long.

If any finless porpoises are found to be behaving abnormally or are pregnant, the keepers will perform ultrasound examinations on them.

The two we just saw, e-bo and YYC, were both born in the aquarium. When e-bo was born, he almost died. Unlike human babies, which usually come out head first, dolphins are usually born with their tails first. After the dolphin's head is exposed, the mother dolphin swims hard, breaks the umbilical cord, and lets the baby swim to the surface of the water to breathe its first breath of air.

When a finless porpoise is born, its tail lobe emerges first, and the entire birth process can last up to one or two hours.

But sometimes accidents happen. When E-Bo was born, her mother Fu Qi didn't know why she didn't swim quickly to cut the umbilical cord, but just stared at E-Bo, at a loss. Time passed by, and if the umbilical cord couldn't be cut quickly, E-Bo couldn't swim to the surface to breathe and might drown.

The dolphin farm immediately decided to let the keeper go into the water to assist Fuqi. The moment the person went into the water, Fuqi was frightened and fled in a hurry. The umbilical cord was successfully cut off, and Ebo was able to float to the surface.

Fortunately, Fu Qi performed well afterwards. E-Bo, who had just been born, was like a toddler, stumbling when swimming and accidentally bumping into the pool wall. Fu Qi would always escort E-Bo and swim on the outside to prevent it from getting hurt. Fortunately, E-Bo's swimming skills improved rapidly, and he was able to control the direction and speed after half an hour.

After the calf is born, the mother dolphin will lift it out of the water and help it breathe.

At present, the breeding technology of dolphin farms is very mature, but raising young dolphins is still a problem. Although the finless porpoise can be brought to the shore and fed with a bottle, it is an aquatic animal after all and cannot leave the water for a long time. The most important thing is that the milk for artificial feeding of finless porpoises can only be replaced by mixed milk from other animals such as goat milk, which is far inferior to finless porpoise breast milk in terms of ingredients and nutritional effects.

Therefore, the finless porpoise cubs are very dependent on their mothers’ care. If the mother porpoise is inexperienced, they can hardly survive with artificial feeding alone. The staff of the porpoise aquarium have also been working hard to overcome the difficulties.

Written by He Changhuan

Photo courtesy of Gao Baoyan, Tang Zhiyuan, Wuhan Baiji Conservation Foundation

WeChat Editor | Ah She Shuang

Source: Museum