The best eater! When a whale opens its mouth, fish will "dive" into its mouth!

Audit expert: Chen Yu

Paleontological restoration artist

Not long ago, CCTV released a video of a Bryde's whale feeding, which attracted the attention of many netizens on Weibo. The scene of the whale opening its "bloody mouth" and swallowing a school of fish was quite shocking, and some people joked that this was a real big stomach "eating show".

Source: CCTV News Weibo

From ancient times to the present, humans have been full of curiosity about whales. People have written their imaginations about whales into books and music. What kind of creature is a whale? What are its living habits? Today, let us get closer to the familiar yet unfamiliar "whale".

Is a whale a fish?

First of all, we need to make it clear that "whales" are not fish . In fact, they are marine mammals that look like fish. It is more accurate to call them whales. As mammals, whales have characteristics such as constant body temperature, breathing with lungs, and viviparous reproduction. At the same time, they have evolved characteristics that adapt to aquatic life, such as a spindle-shaped body in order to swim quickly.

There are about 90 species of whales in the world, and they are widely distributed, from warm equatorial waters to cold polar regions and freshwater areas. The size of whales varies greatly, with the smallest being about 1 meter long and the largest being up to 30 meters long. Based on the presence or absence of teeth, whales can be divided into two categories: toothed whales , which have sharp teeth and number about 75 species, including killer whales and sperm whales; and baleen whales , which have no teeth and number about 15 species, including the blue whale and humpback whale.

The blue whale is the largest animal on Earth Source | Wikipedia

Dolphins look a lot like whales. Do they belong to the cetacean family? Yes. Usually, the cetaceans we refer to are a general term for whales, dolphins, and porpoises, so they are also called cetaceans. Among them, whales are the largest (usually more than 4-5 meters), including all baleen whales and large toothed whale species. The species of the Delphinidae family are generally less than 3 meters long, and porpoises are the smallest, generally only about 1.5 meters. The Yangtze River dolphin that we are familiar with belongs to the porpoise family.

Killer whales actually belong to the dolphin family Source | Wikipedia

Source of Yangtze River Porpoise from Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan｜Wikipedia

In some videos, whales are often seen swimming while spraying water. Why do they spray water? This is because whales need to surface to breathe every once in a while, and exhale carbon dioxide. When the temperature of the exhaled gas is higher than the cold air outside, it will condense to form a water column or air column, just like the white air we exhale in winter. Some larger whales have large lung capacity and can spray water columns up to several meters high, which is quite spectacular. If the blowhole of a whale is on the right or left side of the top of its head, then the water column or air column they spray is tilted, such as sperm whales and killer whales. For scientists and enthusiasts who are familiar with whales, they can identify whale species by the shape and size characteristics of the water column or air column.

The origin of whale blowholes｜unsplash

What does a Bryde's whale look like?

The whale in the video is a Bryde's whale (Balaenoptera brydei), belonging to the Balaenopteridae family and the Balaenoptera genus. Globally, Bryde's whales are mainly distributed in warm waters between 40° north and south latitude. In China, Bryde's whales are distributed in the Yellow Sea, the East China Sea, and the South China Sea. According to past records, Bryde's whales appear more frequently in the Beibu Gulf. Currently, Bryde's whales are listed as a national first-class protected animal.

Bryde's whale source | Guangxi News Channel

The Bryde's whale is dark gray in color, with a black-gray or blue-black back and a yellow-white or white belly. A few individuals have white spots on their bodies. The reason why the Bryde's whale is called the "most unique" whale is first of all its ridgeline. Generally, baleen whales have a raised ridgeline from the blowhole to the tip of the snout, which is 1-2 cm high. In addition to this main ridge, the Bryde's whale also has an obvious secondary ridgeline on each side. Therefore, the Bryde's whale has a total of 3 longitudinal ridges, which is its unique appearance feature.

Dorsal view of the head of a Bryde's whale, showing three distinct ridges Source | He Ruilin et al., "Preliminary Study on Species Identification of Bryde's Whale Populations inhabiting the waters of Weizhou Island in the Beibu Gulf"

Secondly, the shape of the bones of Bryde's whale is unique. Usually, the first rib of baleen whales is shaped like a curved slingshot thin bone plate, but the first rib of Bryde's whale is split into two layers of bone plates at the head where it is connected to the vertebrae, forming a groove in the middle, which is also one of the identification characteristics of Bryde's whale.

The origin of the first rib of Bryde's whale | Wang Pilie, Tang Ruirong, "Anchovy found on the southeast coast of China"

In addition, the swimming style of Bryde's whale is more like that of dolphins. It can dive to a depth of 300 meters underwater. It usually dives for about 2 minutes and no more than 8 minutes at most. Then it jumps out of the water and sprays 4 to 7 times before diving again.

The special way whales eat

Cetaceans are large in size and must consume a lot of food to replenish their energy in order to maintain normal body temperature and metabolic activity in the ocean. Baleen whales have no teeth and feed by filtering , mainly on plankton, crustaceans, schools of small fish, krill, etc.

Source: "In Search of the Mysterious Bryde's Whale"

How much do whales eat? For example, the Bryde's whale (about 8 meters long and weighing about 6 tons) that appeared in Dapeng Bay, Shenzhen last summer can eat about 180 kilograms of food a day . In addition, the way whales hunt has always been talked about.

Whales have a variety of feeding behaviors, including charge feeding, bubble net feeding, suction feeding, slapping feeding, filter feeding, trap feeding, and cooperative feeding.

Here we will talk about the hunting methods of Bryde's whales. Generally speaking, Bryde's whales mainly use the sprint to hunt, which can be divided into forward sprint, right sprint, left sprint, vertical sprint, belly sprint, and treading water.

Here are two of the most spectacular hunting methods: treading water and vertical thrust. When treading water , Bryde's whales will choose the place where the fish are most densely populated, and emerge vertically from underwater, with their lower jaws open nearly 90 degrees, so that the surrounding seawater forms a funnel, and thousands of prey enter the predator's "big mouth trap" along with the seawater. Bryde's whales keep their upper jaws vertically upward for a few seconds to tens of seconds, then slowly enter the water while closing their upper and lower jaws, stay on the water surface for a while, close their mouths and go underwater, and finally expel the water to swallow the food.

Source: CCTV-9 Documentary Channel

When a Bryde's whale is hunting by vertical thrust , it will open its mouth wide and float to the surface of the sea in a nearly upright position, then the lower jaw and upper jaw will fall into the water one by one. During the vertical ascent, the mouth will usually close quickly, which is a significant difference from treading water. When the whale is hunting, there are often seagulls surrounding it. In fact, they are also hunters. After the whale has eaten and drunk enough, these seabirds will snatch the leftovers.

Comparison of treading and vertical thrusting predation behaviors Source: Wu Caiwen, "Study on Population Dynamics and Predation Strategies of Bryde's Whales in Guangxi"

Source: Shenzhen Special Zone Daily

Whales are truly “sea elves”; however, the deterioration of the marine ecology and large-scale commercial whaling have caused their numbers to decrease dramatically. Let each of us start with ourselves to reduce damage to the marine environment. I hope that in the future we can take a “whale watching trip” in the ocean and feel their beauty and shock.