The Number – Cypriniformes
Family – Priniv
The genus/Species – Serrasalmus nattereri
Length: average 20 cm, in some species up to 50 cm.
Mass rarely exceeding 1.5 kg.
Caviar: a few thousand eggs.
The incubation period is 10-15 days, depending on water temperature.
Habits: constant float huge flocks.
Food: primarily fish; attack mammals, floating or come to the waterhole, and birds.
18 known species of piranhas, 4 of which are dangerous to humans, although fatal cases have been identified. Continue reading
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
Sponges that are sold in stores and are used for washing dishes or cleaning the kitchen, not real. They are made from synthetic materials, although very similar to a real sponge and easy to use.
But these sponges appear in the sea, not in a chemical laboratory. For a long time many were convinced that they know all about sponges. It was believed that this plant, until in 1825 a man by the name of Robert Grant proved that sponges were animals!
It considered the sponge in water through a microscope. And saw trickles of water, which went in through one hole and out through another. Still, for many years, scientists did not know what kind of animal. Thought it was a tiny single-celled creatures that live together in one big colony.
We now know that sponges are the dried skeletons of marine animals belonging to the class of “porous”. This is a pretty significant group of animals. Although sponges are one of the lowest forms in the animal Kingdom, their structure is quite complicated. Continue reading