These curious species have incredible peculiarities that allow them to adapt to the marine ecosystem, there are even some with the ability to establish themselves in both environments, all this despite being mammals and that shows us how special they are. Sea mammals, we invite you to meet them right here.
What are Marine Mammals?
They are species that have a bony structure with a backbone, they are also warm-blooded (homeothermic) and conserve mammary glands that produce milk. They usually have hair on different areas of the body and these animals spend most of their time submerged in the Seas and oceans.
There is great diversity among sea mammals, it is estimated that there are approximately 120.000 species.
It is said that the marine fauna evolved after land animals returned to the water more than 66 million years ago and managed to obtain various adaptations, which allows them to live aquatic life and all this occurred as a result of the different environmental conditions .
What are the Marine Mammals?
In marine mammals the following can be found:
- otters: Sea otters and sea cat.
- pinnipeds: Seals, seals and walruses.
- Cetaceans: Whales, dolphins and porpoises.
- Sirenians: Manatees and dugongs.
- Polar Bear: The polar bear is an animal that is not aquatic, but it is named as a marine animal because it spends most of the year on sea ice and is completely adapted to life in the sea.
Within all these groups are the cetaceans and sirenians that live their entire lives in the water, on the other hand the pinnipeds and otters spend part of their lives on land and as a result it is the sirenians and cetaceans that are more adapted to the life in the sea
The aquatic mammal animals are part of a Marine biodiversity of great magnitude and have a long history of commercial exploitation by human beings, all this to obtain meat, fats, oils, skins or ivory, which makes them very defenseless creatures and in danger of disappearing.
It is for this reason that a large part of the marine fauna is under the protection of environmentalists and strongly supported by large groups of protectors of the environment and animal rights, all in order to keep hunters away from them.
In the early years of this era, it was normal to observe marine mammals and appreciate them as sacred creatures with incarnated human souls that symbolized the power and great strength of the sea, for example the whales and dolphins of the ocean.
It is easy to see that these species have colonized a wide range of habitats and can be found in coastal areas and deep oceans.
Origin of these species
Scientific investigations and discoveries of various Types of fossils, let us know that the most archaic ancestors of the mammalian fauna of the ocean inhabited the old ocean of Tethys (in the past tense of the planet), approximately 70 million years ago.
Although it is not known how the evolutionary transformations that gave way to adaptation to the aquatic environment took place, what we know about these is that they belong to the monophyletic group, which means that the different groups of fauna appeared from different ancestors on land. .
That is, they are based on research that has been carried out on ergonomic models of their fossils and their similar molecules. It is for this reason that in cetaceans, dolphins and whales, it is believed that it was an artiodactyl, like pigs or cows, which was a distant relative of the hippos.
We can also find the sirenians, which in their case was a proboscidean linked to the pachyderms, and the pinnipeds have a common ancestor of mustelids and bears.
Later, these three groups welcomed the physical qualities of their peers, which were adequate to their demands to adapt to marine life, which is known as the convergence of evolution.
Many of these marine animals have a restricted distribution in circumpolar areas, such as; whales, pygmies, narwhals, beluga, among others and some of wide distribution, that is, they can be found anywhere on the planet.
Adaptation to the Aquatic Environment
In the evolutionary process, aquatic mammals they had different physiological and functional transformations, which allowed them to adapt to life in the new aquatic environment.
If we want to understand the adaptation phase, we have to know that different physical qualities are needed in the marine environment than those of surface animals and therefore, the animals that wish to inhabit the aquatic environment must first adapt to it.
However, in order to understand the adaptation phase, we must take into account some issues that have to do with the characteristics of the aquatic environment. We are first forced to understand that the consistency of water is three times that of wind and that the viscosity is about sixty times that when they are in similar tempers.
It happens that these two affect friction, because they are energies contrary to the activity of water. In addition, another significant factor in the marine environment is pressure, that is, the force that is exerted on a body and tends to oppress it, is stronger than on the surface.
As well as the thermal conductivity, which is greater in water than in the wind and it can be said that the transmission of heat from a body to the outside and the light force is reduced further. After these conditions are given, marine mammals must adapt to them, and some of these are the following:
- Thermoregulatory Adaptations: For example, we observe in otters the hair as an insulator of water, endothermic or hypothermic, generating internal heat, or the thickness of the layer of fat under the dermis.
- Hydrodynamic Adaptations: Their trunks are pisciform, that is, they are similar to those of fish, their extremities and tails are turned into fins, their hair disappears or decreases, which reduces resistance when swimming and shrinkage along their necks.
- respiratory adaptations: These have huge respiratory cavities, which allows them to perform a more efficient gas exchange, they have an increase in pulmonary insufficiencies and this is due to the location of the diaphragm in their body or the expulsion of air into the environment, instead of inhaling it to prevent an embolism in very high temperatures.
- Reproductive Adaptations: In this aspect they have spacious mouths, which help them to avoid the loss of breast milk during the lactation process, or very thick and abundant milk to avoid loss to the environment.