Whale falls, the most gentle death in the world
If the seabed is a desert without sunlight, then “Whale Fall” is an oasis in the deep sea. The whale falls with its gentle and powerful power to nourish the creatures that struggle to survive in the dark. So there is this sentence: “When a whale falls, everything is born.”
What is a whale fall? Whale landing is a process in which a whale dies and sinks into the deep sea more than 1,000 meters. It is an ecological community formed by whale carcasses in the deep sea, and it is also an important nourishment for countless lives in the ocean.
In 1987, a team of scientists led by oceanographer Craig Smith at the University of Hawaii discovered the first whale fall ecosystem. Since then, with the continuous development of deep-sea exploration technology, mankind has gradually gained a deeper understanding of the ecological succession model of the deep seabed. According to reports, on April 3, 2020, Chinese scientists discovered a whale landing about 3 meters long in the South China Sea for the first time. Such complete whale landings are actually very rare. So far, fewer than 50 natural whale landings have been discovered.
From giant whales (such as sperm whales and most types of baleen whales) naturally dying in the deep sea area and beginning to sink, to the gradual disappearance of huge whale carcasses on the bottom of the sea, the whole process can be divided into four stages. Due to the difference in the individual size of whales, the depth of sea water and other environmental variables (such as tidal currents), the duration of each stage is different. Of course, not all whales can form a whale fall after death. Smaller cetaceans such as dolphins, due to their small size and low lipid content, will not go through the same ecological succession stage.
When the whale carcass starts to fall, the initial stage of the whale fall begins. This stage is called the “moving scavenger”. Because at this time, thousands of marine creatures “heard the news” and began to eat and decompose whale carcasses. In this “gluttonous feast”, eight-headed eels and sharks are the most active. They feed on the soft tissues of whale carcasses and consume up to 40 kg to 60 kg per day. They are the main “clearing” in the process of whale landing. Astoria”. Due to the different sizes of whales, this stage usually lasts from several months to one and a half years, during which 90% of the whale carcasses will be decomposed.
When the first “feast” was over, the whale carcass was almost left with a skeleton. The whale bones that sink into the seabed will form a new ecological environment on the seabed, providing suitable living conditions for invertebrates, especially polychaetes such as worms, and crustaceans such as shrimps and crabs. These animals live in whale bones and the surrounding sediments, while gnawing on the remaining skin and flesh of whale bones, while providing species diversity to the deep sea. Therefore, the second stage is also called the “get rich opportunist stage.”
After the second stage, which lasted 4 to 5 years, the whale carcass was left with a naked skeleton. When the whale falls into the third stage, it will usher in a new batch of “immigrants”-anaerobic bacteria. Anaerobic bacteria are sulphur-loving and can decompose lipids in bones, reduce sulfates and discharge a large amount of hydrogen sulfide. Although hydrogen sulfide is harmful to the human body, it can form an environment suitable for the survival of autotrophic bacteria in the deep sea. These bacteria, which can grow and reproduce normally without relying on any organic nutrients, can grow rapidly in this environment and nourish marine life such as mussels, clams, limpets, and sea snails. Whale bones are rich in lipids, which account for 4% to 6% of their body weight, so this “chemoautotrophic stage” can last for 50 to 100 years.
After the third stage, although the “life nutrients” in the whale bones disappeared, the gift that the whale fell to the ocean did not disappear. Once the organic compounds in the whale fall are exhausted, it will enter the fourth stage of ecological succession, which scientists call the “reef stage.” Only bones with mineral deposits will become habitats for seabed organisms and provide them with a solid substrate.
Scientists discovered when exploring whale falls that this unique ecosystem has created a complex living environment on the seafloor and promoted the production of new species in the ocean (such as the new worm species discovered by scientists-bone-eating worms). Thousands of lives in China provide energy.
However, not all whale lives have a perfect curtain call. If the whale dies and strands on the coast, it will become a time bomb and a whale burst. This is because once it leaves the sea, the body temperature of the whale will rise, and a big explosion will be brewing in the huge body. After the whale dies, the food and organs left in the body begin to decay, and bacteria begin to multiply rapidly. The large amount of gas produced in this process gradually increases the pressure in the corpse. Once the pressure exceeds the critical value, an explosion will occur-the corrupted gas and internal organs in the body will burst out, methane, hydrogen sulfide, ammonia and other gases. The stench will not dissipate for a long time.
The whale used the whale to fall such a hundred-year-long curtain call to repay the vast ocean that gave it life. Under the influence of human activities and environmental changes, the number of whales today is embarrassing. If the whale falls no longer appear, the rich deep ocean may gradually become a barren desert.