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Marine mammals, large or small, aggressive or peaceful. There are various types but few are the ones we really know. It is a shame because our planet is home to wonderful creatures even under the sea or near it, some of them are also endangered by climate change and water pollution. Knowing them better, perhaps, is the way to become more sensitive to environmental problems that always seem too far away to us to want to commit ourselves and do our part.
THE marine mammals, alone, they constitute a large family that includes other subfamilies whose members are very different from each other. They have evolved over the millennia independently and today they would not even be called relatives.
Marine mammals: characteristics
IS' difficult to define the characteristics of marine mammals that they are valid "in general", it is better to divide them first into three large families: cetaceans, sirenii and carnivores. Even within these, it is necessary to specify that there are animals that live 24 hours a day in the sea, like cetaceans and sirenii, others who instead moved to dry land to survive, changing not only their appearance but also their habits.
Carnivores have done it, and an example known to all is that of polar bears, marine mammals that today we find on the Arctic Circle, almost confined there. Other subspecies of sirenidii, on the other hand, such as seals, sea lions and walruses, are more widespread and scattered around the planet as well as some mustelids such as sea otters.
Marine mammals: representative species
Among the cetaceans we find some marine mammals Representatives that even non-experts may certainly have already heard. In the suborder of Odontocetes, we find dolphins and killer whales while in that of Misticeti, humpback whales, sperm whales and fin whales.
THE cetaceans are perhaps the first that come to mind if we think of marine mammals and they deserve this glory since they have been able to adapt during evolution, staging a great mutation: from full of hair they have become almost "naked". Today in fact if you look at it a humpback whale, there are protuberances on the head that recall the evolution of the species.
In carnivores, divided into Fissipeds and Pinnipeds, we find representative species that are very different from each other. In fact, both the polar bears and sea otters but also seals, sea otters, sea lions, and walruses.
Moving on to the family of the Sirenii, composed by Dugongids and Trichechids, in marine mammals we also discover animals such as manatees.
Marine mammals: list
Those who do not want to forget even a marine mammal can purchase and study the volume "Whales, dolphins, seals. Field guide to the marine mammals of the world " by Hadoram Shirihai.
Marine mammals: weight
The cetaceans, but not only them, have a considerable weight, a rather widespread characteristic in marine mammals of all known families so far. There Blue whaleHowever, it has been called the largest living animal in the world with its over 33 and a half meters in length and its sweet weight equal to 190 tons.
To imagine it correctly, it should be compared to a ten-story building that weighs as much as 280 people. We find it among the marine mammals, in the suborder of the Mysticetes, it is a whale with baleen, horny lamellar formations present in its mouth instead of teeth. They are used to filter the expelled water and retain crustaceans, molluscs, jellyfish, krill and plankton for food.
Marine mammals: seals and sea lions
Among the marine mammals there are often species that are difficult to distinguish especially in the eyes of those who are not experts in the genus. An example is that of seals and sea lions. There are differences between the two species, of course, but you can only see them by carefully observing the physical conformation and the way of swimming. They are both belonging to the group of Pinnipeds, the seals are known only and only as seals, the sea lions can also be heard called sea lions, from the Greek otos which means ear. This already gives us a clue as to what is a difference between the two animals. The sea lions they are equipped with auricles, the seals do not.
We continue by saying that sea lions and seals can also be distinguished by how they swim and how they move on land. The former move with greater agility, they only use their forelimbs to swim and do nothing but rhythmically alternate front and hind legs to advance on land. The seals? They use their hind limbs to swim and drag on land awkwardly on the belly dragging itself with the front limbs.
The posture of the two animals is also different, the seals are unable to turn them forward rear fins, the sea lions yes and in fact they are able to assume a semi-upright position
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