A huge number of living beings live on our planet, surprising with their species and forms. Among them there is an interesting and unique animal - a mammal siren that lives in sea and fresh waters. It is represented by several species, different in their characteristics.
Description
Exploring the fossil remains of animals, scientists came to the conclusion that the ancestors of the sirens lived in shallow water. They had four limbs, went to land and ate grass. The number of remains of animals like sirens speaks of their large population.
During the evolution of these mammals, the hind limbs disappeared and a fin appeared instead.
Thanks to modern technology, seeing a photo of a siren is quite easy.
These amazing mammals have a very cautious nature. They never leave the expanses of water, so it is impossible to meet them on land. Move slowly and smoothly.
They live in small families or one individual at a time. Life expectancy is about 20 years.
Habitats
Siren mammals are adapted to live only in water. Mostly choose warm shallow water. Depending on the species, they live in both s alty and fresh waters. Distributed in the waters of the Amazon River, the Indian Ocean, along the Atlantic coast of America, the western coast of Africa, near the Caribbean islands, the waters of Brazil and some other countries.
Characteristic
The body of the sirens has a very interesting structure, shaped like a cylinder. The length can be from 2.5 meters to 6 meters. Body weight reaches 650 kilograms.
Sirens' animal bones are heavy and have a dense structure. In the course of evolution, fins were formed from the tail and forelimbs.
The front limbs are shaped like flippers. Very mobile in the elbow and wrist joint. Five fingers are distinguished on the skeleton of the animal, but it is impossible to detect them in appearance, since they are covered with one skin and form a fin.
Hind limbs gradually disappeared. Now they cannot be seen even in the structure of the skeleton of these mammals. Sirens also lack a dorsal fin.
The back fin has no rounded bones. Essential for locomotion and navigation.
The skin has sparse hairs resembling bristles. The skin forms folds on the body, its thickness is quite large. Under the skin is a well-developed layer of adipose tissue.
Elongated head, rounded, with small eyes,nostrils and mouth. There are whiskers on the head, which, together with a developed upper lip, perform a tactile function and help the siren to explore objects. The animal does not have auricles. Auditory openings are relatively small. The number of teeth depends on the type and age of the animal. The small and short tongue is calloused in structure.
Classification
Siren mammals are currently divided into two families.
Dugong. The only representative of the family living in our time is the dugong. The average body length is from 2 to 4 meters, weight up to 600 kilograms. The largest number of individuals inhabits the Torres Strait and the Great Barrier Reef. They live in warm shallow water, often alone. There are known cases of dugongs entering the sea and estuaries. Among the striking differences from other sirens is the presence of a tail, divided by a recess into two parts. She also has larger and more elongated lips.
Extinct representatives of the dugong family are sea cows. They differed in large sizes: the length reached 10 meters, the weight was up to 10 tons. They lived in the waters of the Pacific Ocean in shallow water, without sinking too deep. They led a herd life, had a calm character.
Manatees. Divided into four types:
- American manatee. The average body length is 3 meters, weight is from 200 to 600 kilograms, and females are usually larger than males. They live in small swampy areas of the Caribbean Sea in the region of South, Central and North America; in places rich in abundant vegetation suitable for food, without the presence of enemies among othersanimals. Since it has a small layer of fatty tissue, it prefers only warm water. It has a gray color with a blue tint. The American manatee is able to take root in both s alt and fresh water, adapt to a polluted environment.
- Amazonian manatee. Habitat is typical only for the waters of the Amazon River. Does not survive in s alt water. Prefers deep and still waters. The color is dark gray, it is distinguished by smoother skin, the presence of one or more white spots on the chest. It has small dimensions: average length is 2.5 meters, weight is 400 kilograms. The most dangerous natural enemies are crocodiles and jaguars.
Below is a photo of an Amazonian manatee siren.
- African manatee. Distributed in coastal waters, rivers and lakes along the western coast of Africa. Avoids waters with high salinity. The characteristics are very similar to the American manatee. The main difference is the black and gray color of the skin. It is most active at night.
- Pygmy manatee. Little is known about the life of this species. It lives in the rivers of the Amazon basin, choosing areas with fast water movement. Among the sirens, it has the smallest dimensions. The average body length is only 130 centimeters, weight 60 kilograms. The skin color is black with a white patch on the chest, like the Amazonian manatee.
Food
Sirens are herbivores. Since they never go to land, they feed on sea grass and algae that growat the bottom of the reservoir. The upper lip is well developed, which allows it to successfully grab and pluck plants.
Food for some species is also fruits and leaves of trees that have fallen or hanging low to the water.
In some cases, sirens can eat fish and invertebrate marine animals. This usually happens when there is a lack of plant foods. Also, with a limited amount of algae and grass, these animals migrate in search of places rich in suitable food.
Behavior
Siren mammals have a very calm and slow nature.
Individuals communicate with each other using special signals that notify of possible danger, serve as a means of communication between the female and the cub, or are a call during the breeding season.
The body of the sirens is arranged in such a way that it is easy to confuse the animals with bathing people. Perhaps this was the reason for the unusual name of mammals, taken from Greek mythology. The Song of the Sirens is also related to creatures from fairy tales. And it doesn't apply to mammals. Animals make sounds that are more like crackling than the singing of sirens from mythology.
When threatened by predators, they most often flee.
Mainly lead a solitary life. Sometimes they can gather in small groups in places rich in marine vegetation.
Do not descend to great depths, as they emerge from the water every 3-5 minutes to breathe.
Reproduction
The breeding period is not tiedto a certain time, occurs within a year. At this time, females secrete a special enzyme. They also call on males with characteristic sounds. Males may be aggressive towards each other due to the attention of the female.
The Sirens' pregnancy lasts a little over a year. Births take place in shallow waters. As a rule, one cub is born (two - very rarely) weighing from 20 to 30 kilograms and about one meter long. Feeding is quite long, from a year to a year and a half, despite the fact that the cub is able to eat plant foods at about three months.
The bond between a female and her cub is long-lasting and especially affectionate. Males do not take part in the development of offspring.
Sources of threat to life
Unfortunately, today these amazing mammals are endangered. The reason for this was the hunt for valuable meat and the skin of this animal, as well as damage received from the movement of the blades of the engines of ships and boats. It is not uncommon for sirens to fall into fishing nets.
Environmental pollution also contributes to a significant decrease in the number of these animals.
Mammals sirens have enemies in their natural environment. These are sharks, crocodiles and jaguars.
