In winter, the temperature gradually drops, and rivers and lakes in the north begin to freeze; in the early morning in the south, a layer of hoarfrost forms on the leaves. People have long put on cotton clothes to keep out the cold, and the animals on the land have also used various skills to resist the cold-some have replaced them with finer fur; some have simply hid and hibernated and “slept over the whole winter”; Some even cross half of the earth and migrate to warm places for the winter. So, do animals in the ocean also need to resist the cold? How do they spend the winter? Now, let’s go to the sea to find the answer.
Before going to sea, let’s answer two more common questions:
Is the sea cold in winter?
As the temperature of the atmosphere drops, the temperature of the sea water also drops accordingly. Although the temperature change of sea water is slower than that of land due to the difference in specific heat capacity, the sea water is still colder in winter compared with warm season. However, the sea temperature of different latitudes is of course different, and the difference is quite big. For example, the South my country Sea in the southern tip of China has a surface sea temperature of about 25 degrees Celsius in winter, while the surface water temperature of the Bohai Sea in the north is only 1 degrees Celsius.
Are marine animals afraid of cold?
The distribution of marine animals is extremely wide, from the hot near the equator to the cold polar waters, from the shallow ocean to the deep ocean where no sunlight can be seen. Marine animals living in different environments have their adaptability, so marine animals living in the Arctic and Antarctic can be said to be cold-resistant. For example, Antarctic krill can live at around 0 degrees Celsius for life. But if some marine animals that live in the tropics are moved to cold waters, there is only a dead end.
We all know that under standard atmospheric pressure, pure water freezes at 0 degrees Celsius, but because seawater contains salt, the temperature required for freezing is lower. Therefore, seawater at 0 degrees Celsius will not freeze, but also Fish live here. Scientists conducted research on these frigid fish and discovered an “antifreeze protein” from flounder and sculptor. It is the presence of this protein that reduces the freezing point of fish body fluids to minus 2.2 degrees Celsius, allowing them to adapt to extremes. Ability for severe cold.
Different types of marine animals have different adaptability to temperature. Today we are going to discuss how marine animals adapt to winter, so we want to focus on those marine animals that live in temperate waters. The temperate zone has four distinct seasons, and the temperature difference between winter and summer is large. Therefore, animals will show different living conditions in different seasons.
After understanding these two issues, our exploration officially began. Sea animals spend the winter, it can be said that they have their own unique tricks——
Move to a warm place
The oceans on the earth are quite vast. For those marine animals with strong swimming ability, winter is coming. “Moving” to a warm place and “living” can be said to be the simplest and most direct way to spend the winter. Therefore, many marine animals migrate on a large scale in winter, and this behavior is called winter migration in zoology.
Hairtails that search for food in the southern part of the Yellow Sea in July and August each year will migrate in groups to the Yangtze Estuary waters after October, and then partly go to the open sea, and partly go south to the central and southern East China Sea. We call the area where the fish spend the winter concentratedly, which is called the overwintering ground for certain fish. For the overwintering fish, it is very important to ensure the smooth migration route. After spending the winter in the wintering grounds, the hairtail school will start to migrate northward in March and April each year, and wait until October to continue the journey to the south.
In addition to fish, shrimp and crabs also have the ability to migrate through the winter. The swimming crab is a kind of crab family with strong swimming ability. If you carefully observe the feet of the swimming crab, you will find that its last pair of feet is flat, like a boat oar, called “swimming feet”, this pair of feet is big Improve the swimming ability of swimming crabs. Take Portunus occidentalis living in the waters of Zhoushan, Zhejiang Province as an example. After October, when the water temperature drops, they begin to migrate from north to south. From November to February of the next year, they will migrate to Yushan Island, Wenzhou and other southern Zhejiang fishing grounds. During the winter in the sea area, part of it will reach Xiamen sea area.
The last pair of feet of the swimming crab is oar-shaped, which can help it swim in the ocean
Reduce consumption and preserve strength
Fish living in the sea can spend the winter by migrating long distances, but animals such as snails and shellfish living in tidal flats do not have this condition. So how do these animals spend the winter?
Unlike humans, which are warm-blooded animals, snails and shellfish are thermophilic animals. Their body temperature changes with changes in the outside temperature. They can survive even if they are in a low temperature state for a long time. So compared to the cold, the greater threat these animals face in winter is the shortage of food.
In this case, they figure out a way to deal with hunger. Before the cold winter comes, these snails and shellfish start to eat in large quantities to accumulate their own energy. When the external temperature decreases, they will reduce their food intake, reduce metabolism, and inhibit body growth. This reduces the body’s energy consumption and helps them to pass the winter smoothly.
Some oysters stop growing and enter a “dormant” state below 10 degrees Celsius
do you know
The characteristic of temperature-changing animals that adapt to temperature by reducing their metabolism provides a new way for people to transport seafood over long distances. For example, constrictor clams can still survive after a few days of storage under low temperature and mud conditions. Nowadays, some universities have also developed the technology of “freezing live fish”-the fresh fish are frozen and stored in a special way, and the fish can still swim after being thawed again! Isn’t it amazing? This technology has not yet been put into practical use due to restrictions on energy consumption, success rate, and external conditions. However, with the further development of research, it is believed that this technology will soon be used in a variety of industries.
Change form to continue life
There are still many types of animals in the ocean that cannot survive the winter, so how do these animals keep going?
There is such an animal, although its structure is simple, its status is very important. It has appeared 650 million years ago. It is the first animal to have nerves. This is the jellyfish. Today, let’s not talk about the classification and status of jellyfish, just talk about how jellyfish spend the winter.
Jellyfish is a kind of marine animal that everyone is familiar with. Those who have been to the aquarium will surely be impressed by the colorful and dreamlike jellyfish exhibition tanks. There is a category of members in the jellyfish family, which is well-known to every household, which is the jellyfish. Upon hearing this name, was your first reaction “delicious”? As an annual animal, jellyfish cannot survive the cold winter, but they also have their own tricks. At the end of summer, the jellyfish will give birth to their own offspring. The newly born baby jellyfish look completely different from their parents. They have another name—hydra. Unlike the swimming jellyfish, the hydrops are very small, about the size of a pencil tip. They have very weak mobility and live by attaching to other surfaces. But the vitality of the polyp is quite tenacious, and it can survive even in low temperature environments. When the winter is over and the good time comes when the temperature is suitable and the food is abundant, the polyps will continue to reproduce themselves to form a large area of polyps. At the same time, each polyid will form dozens of jellyfish through growth and morphological changes.
Except for jellyfish, most large temperate jellyfish, such as sea moon jellyfish and white cloud jellyfish, have this characteristic. Not only jellyfish, but some squids, small plankton arthropods, etc. can also leave offspring in the form of eggs and spend the winter, thus ensuring the continuation of their race.
Sea moon jellyfish
When there is a special way
The coldness of Antarctica is self-evident, and the emperor penguins living here, as a kind of “alternative” marine animals, have their own set of special methods to keep out the cold, that is, everyone gathers together and hugs each other to reduce heat. Lost, use collective strength to resist the severe cold, and spend the cold winter together.
When you come to the beach and hold up a glass of sea water, the sea seems clear and transparent, but it actually carries life; when you squat on the beach and lift a rock, you may see a small crab escaping quickly; when you Coming to the wide sea by boat, you may encounter giants such as whales and sharks… These marine animals seem to be very different, but they all have unique skills. Regardless of whether they are strong or weak, facing the severe test of the cold winter, although they are unwell, they are striving to survive, forming a huge and colorful ocean world together.