As an important module of knowledge, the evolutionary tree is contained in a variety of organisms. Among them, mammals have added marine animals - sperm whales! Compared to elephants and leopards, this new member is somewhat unfamiliar. Next, let Xiaobian briefly introduce it for everyone.
I believe that many students may have questions, elephants, leopards and sperm whales are far from the size and living environment, why are they all mammals? First, let's review the knowledge point: What are the main characteristics of mammals?
Body surface coat
With the exception of a few aquatic species such as whales, which have degenerated body hair, mammals have coated surfaces. Body hair has a good thermal insulation effect. Mammals can maintain a constant body temperature and are thermostatic animals.
Prenatal birth, breastfeeding
Mammals reproduce differently from other animals: the vast majority of mammalian embryos develop in the female, obtain nutrition from the mother through the placenta, and produce from the mother after developing to a certain stage, this mode of reproduction is called viviparous birth. Females feed their offspring with their own milk, allowing them to grow up in superior nutritional conditions. Viviparation and breastfeeding improve the survival rate of offspring.
Teeth have incisors, canine teeth and molars
Unlike birds, which peck at food with their beaks, mammals use their teeth to bite, cut and chew food. Their teeth have incisors, canine teeth and molars. Tooth differentiation improves both the mammal's ability to ingest food and the ability to digest food.
Sperm whales are 11–20 m long for males and 8.2–18 m for females with an adult weight of 25–45 tonnes; juveniles are 4 m long at birth and weigh up to 500 kg. Compared to the body, the sperm whale's head appears disproportionately heavy and large, with the largest brain in the animal kingdom, while the tail appears both light and small, which makes the sperm whale's body resemble a large tadpole. Its nostrils are located on either side of the front left of the top of this huge box. Unusually, although the sperm whale has two nostrils, only the left nostril is unblocked for breathing, while the right nostril is naturally blocked, which causes the sperm whale to always be on the right side of the body when it surfaces to breathe, and the water mist column is sprayed at an angle of about 45 ° to the left front.
Its head is full of whale brain oil, also known as cetacean. It is a type of fat that has a melting point close to the body temperature of a sperm whale. In 1971, a British scientist proposed that brain oil is the key to the deep diving ability of sperm whales - they use seawater to cool brain oil into solids, or warm brain oil with blood into liquid, so as to change the proportion of the head, to achieve diving or floating. With the help of brain oil, sperm whales are crowned mammalian diving champions. Tracked by sonar, sperm whales were found to dive to depths of up to 2250 meters. Extrapolating from the food in their stomachs, they can even dive into the deep sea at a depth of more than 3,000 meters.
The mention of sperm whales reminds you of ambergris. Ambergris is a waxy substance that occasionally forms in the intestines of sperm whales and is mainly used as a fixative for perfumes. Ambergris has a dark brown appearance and a pale yellow to grey interior, weighing from 0.1 to 10 kg.
So how exactly is ambergris formed? It turns out that the squid in the deep sea is the main food of sperm whales. The flesh of the squid is soft, but the bird's beak-like jaw pieces and endoskeleton are difficult to digest, usually remaining in the stomach and occasionally entering the intestine, mixing with feces to form fecal stones. This fecal stone is like a small dam, intercepting the new solids brought by the fecal liquid, which is wrapped larger and larger, and after a complex process of bacteria and various enzymes, it finally forms - ambergris. Freshly discharged ambergris is dark and soft, with a bad smell, but after years of washing in sunlight, air and seawater, it hardens, fades and emits aroma, which can be used to make perfumes.
Because of its treasure, the sperm whale was once indiscriminately killed and used by people to make valuable handicrafts, and the sperm whale has been listed as an endangered species in the world.
Sperm whales, like bats on land, look for direction underwater by discerning echoes. Seismic studies, naval exercises, and noise from ships can mislead them, sometimes causing entire groups of whales to run aground and die.
Not only is it harmful to marine life such as sperm whales, but the oceans in which they live are also under threat. It was once thought that the ocean was so vast that whatever we do with it would have no impact. But much of the marine habitat has been destroyed by a combination of pollution, overfishing and coastal development, and in some parts of the world, large seabeds near large cities have been turned into toxic underwater deserts.
Our future depends on healthy oceans and the fish they provide. The ocean is an important part of the food chain, not only sustaining humans, but also feeding on the flora and fauna on land. It is reassuring that many people are doing their utmost to protect the oceans and marine life. All of us can get involved, such as cleaning up the litter that could end up in the oceans; buying only large supplies of fish; burning less fossil fuels that can cause global warming, and so on.