A huge number of living creatures 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 on land and ate grass. The number of animal remains like sirens indicates their large population.
During evolution, the hind limbs disappeared in these mammals and a fin appeared in their place.
Thanks to modern technology, seeing a photo of a siren is quite simple.
These amazing mammals are very cautious. Water spaces never leave, therefore it is impossible to meet them on land. They move slowly and smoothly.
They live in small families or one at a time. Life expectancy is about 20 years.
Habitat
Mammal sirens are adapted for life only in water. Mostly choose warm shallow water. Depending on the species, they live in both salt and fresh water bodies. Distributed in the waters of the Amazon River, Indian Ocean, along the Atlantic coast of America, the western coast of Africa, near the islands of the Caribbean, the waters of Brazil and some other countries.
Characteristic
The body of sirens has a very interesting structure, resembling a cylinder in shape. The length can be from 2.5 meters to 6 meters. Body weight reaches 650 kilograms.
The bones of animal sirens are heavy, have a dense structure. During evolution, fins formed from the tail and forelimbs.
The forelimbs are in the form of fins. Very mobile in the elbow and wrist joint. Five fingers are distinguished on the skeleton of an animal, but it is impossible to detect them in appearance, since they are covered by one skin and form a fin.
The hind limbs gradually disappeared. Now they cannot be seen even in the structure of the skeleton of these mammals. Sirens also do not have a dorsal fin.
The posterior fin is rounded in shape with no bones. It is necessary for the implementation of motor function 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 fatty tissue.
The head is elongated, rounded, with small eyes, nostrils and mouth. A mustache is located on the head, which, together with the developed upper lip, performs a tactile function and helps the siren to examine objects. The animal does not have auricles. The auditory openings are relatively small. The number of teeth depends on the type and age of the animal. The small and short tongue is callous in structure.
Classification
Mammal sirens today are divided into two families.
Dugongs. The only representative of the family living in our time is a dugong. The average body length 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 singly. 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. And also has larger and more elongated lips.
Extinct members of the dugong family are sea cows. They differed in large sizes: the length reached 10 meters, weight up to 10 tons. Inhabited the waters of the Pacific Ocean in shallow water, not sinking too deeply. They led a herd lifestyle, had a calm character.
Manatees. They are 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 shallow marshy areas of the Caribbean Sea in the region of South, Central and North America; in places rich in plentiful vegetation suitable for food, without the presence of enemies among other animals. Since it has a small layer of fatty tissue, it prefers only warm water. It has a gray color with a blue tint. American manatee is able to take root in both salt and fresh water, adapt to a polluted ecology.
- Amazon manatee. Habitat is characteristic only of the Amazon river. It does not take root in salt water. Prefers deep and quiet waters. The color is dark gray, has a smoother skin, the presence of one or more white spots on the chest. It has small dimensions: average length 2.5 meters, weight 400 kilograms. The most dangerous natural enemies are crocodiles and jaguars.
Below is a photo of a siren of the Amazonian manatee species.
- African manatee. Distributed in coastal waters, rivers and lakes along the west coast of Africa. Avoid waters with high salinity. The characteristics are very similar to the American manatee. The main difference is the black-gray skin color. It is most active in the dark.
- Dwarf manatee. Little is known about the activity of this species. It lives in the rivers of the Amazonian basin, choosing sites with the rapid movement of water. Among the sirens it has the smallest sizes. The average body length is only 130 centimeters, weight 60 kilograms. The color of the skin is black with a white spot on the chest, as in the Amazonian manatee.
Nutrition
Sirens are herbivores. Since they never go to land, the food for them is sea grass and algae growing at the bottom of the reservoir. The upper lip is well developed, which allows you to successfully grab and pluck plants.
Fruits or leaves of trees that have fallen or low-hanging to the water also serve as a food source for some species.
In some cases, sirens can consume fish and invertebrate marine animals. This usually occurs with 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
Mammals sirens are very calm and slow.
Individuals communicate with each other with the help of special signals that indicate a possible danger, serve as a means of communication between the female and the cub, or are an appeal during the breeding season.
The body of the sirens is designed so that animals are easily confused with swimming people. Perhaps this was the reason for the unusual name of mammals, taken from Greek mythology. The siren song also relates to creatures from fairy tales. And does not apply to mammals. Animals make sounds, more like crackling than singing sirens from mythology.
When threatened by predators, they most often flee.
Mostly lead a solitary lifestyle. Sometimes they can gather in small groups in places rich in marine vegetation.
Do not sink to great depths, as they emerge from the water every 3-5 minutes to breathe.
Breeding
The breeding season is not tied to a specific time, occurs throughout the year. At this time, females secrete a special enzyme. And also call males with characteristic sounds. Males can be aggressive towards each other due to female attention.
Pregnancy sirens lasts a little over a year. Childbirth occurs in shallow places. As a rule, one cub is born (two very rarely) weighing from 20 to 30 kilograms and about one meter long. Feeding is quite lengthy, from a year to a year and a half, despite the fact that the cub is able to eat plant food for about three months.
The bond between the female and her cub is distinguished by its duration and special affection. 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 skin of this animal, as well as damage caused by the movement of the blades of the motors of ships and boats. There are frequent cases of sirens getting into fishing nets.
Environmental pollution also contributes to a significant reduction in the number of these animals.
Mammal sirens have enemies in their natural environment. These are sharks, crocodiles and jaguars.