Hundreds of thousands of years ago, long before the appearance on Earth of man, the oceans already swam fish. At that time they were the most highly developed creatures.
Since then, they began to develop a variety of ways so that now only some species only vaguely resemble the first primitive ocean fishes.
As a rule, fish has an elongated and tapering shape. People have copied it in the construction of ships and submarines, as it is the best adapted to movement in water.
Most fish use their tail as a motor. With the help of fins and they control their movements. Except for one species of fish, all the others breathe by means of gills. Fish swallows mouth water that passes through the gills and out through the hole. Water also contains oxygen, and it through the gills into the blood of fish, as the air through the lungs in the blood of man. Continue reading
Watching fish in an aquarium, you’d think they never rest or sleep. In the understanding of man, they are in constant motion. However, like all animals, fish periods of active behavior alternate with phases of slowing of physical functions – this is the dream fish.
Dream fish is different from our understanding of sleep. Structural features and habitat not allow the fish to fall into a state in which they would be completely disconnected from reality. In such a state is immersed most mammals during sleep. The fish also during sleep, the brain activity remains unchanged, – they are not able to fall into a state of deep sleep.
This feature and may cause the issue: how do aquarium fish sleep?
Studying the behavior of aquarium fish, you will notice that at certain times the fish are almost motionless, transfixed in the water. This is the sleeping fish. During sleep, the fish usually drift without active movement. But the slightest influence of external factors leads fish into an active state. Continue reading
Floating jellyfish in the sea often struck by its beauty. Such a wealth of shapes, colors, as among the jellyfish, not to meet many animals! Jellyfish inhabit all seas, and some of these sea animals prefer warm waters of the tropics and subtropics, while others liked the cool Northern parts of the oceans.
Some jellyfish can be found at a depth of 10km, and there are jellyfish that do not leave the coastal strip. It is noteworthy that each type of jellyfish is found only on the territory of the area is an animal does not apply to pandemic, that is common everywhere.
The largest jellyfish is Cyanea arctica – chosen by a cool North sea. The age of lanei can be identified by its colour – older individuals are covered with brown and red spots; the young specimens are painted in an intense orange color. Continue reading