Lovers of aquarium fish are familiar with many of their breeds, but not all. But all aquarists are well aware of a small crayfish that goes to their pets for food — gammarus .
The appearance of gammarus
The gammaride family belongs to the genus of higher crayfish. Gammarus enters the detachment of bokoplavov and has more than 200 species. The common name of the poplar in the people is mormysh, and it unites more than 4,500 species.
These are small creatures, about 1 cm long. Their body is bent in an arc, protected by a chitinous cover, which consists of 14 components. The color of gammarus depends on the food he eats.
The crustaceans that feed on plants have a greenish color, there are brown and yellowish, variegated live in the Baikal, and deep-water species are mostly colorless. There are organs of vision — two complex eyes, and organs of touch — two pairs of antennae on the head. One pair of mustaches pointing forward and longer, the second looking back.
Gammarus has 9 pairs of legs, and each pair has its own function. The chest legs have gills that serve for breathing. They are protected by thin but durable plates. The limbs themselves are constantly in motion to ensure the flow of fresh water and oxygen. Also on the two front pairs there are claws that are needed to capture prey and help to cling to the female stronger during reproduction.
Three pairs of legs on the abdomen are used for swimming and are provided with bristles. The last three pairs are directed backwards and have a leaf-like shape; by them and by the tail the crustaceans repel each other and make sharp translational movements.
They are also covered with bristles. These tools gammarus sets a direction. The body of the female is also equipped with a special brood chamber, which is located on the chest.
The habitat of Gammarus is very wide — it lives in most of the Northern Hemisphere, it also includes China, Japan, and many islands. On the territory of our country a large variety of species is found in Lake Baikal. Different species are found almost throughout the world.
Gammarus lives in freshwater bodies, but many species also live in brackish waters. They are suitable rivers, lakes, ponds. Chooses clean water, by the presence of gammarus in the water, you can determine the degree of oxygen in the pond.
He likes the cold season, but can live at temperatures up to +25 С⁰. In the heat, it is often at the bottom, under cool stones, among algae, snags, where there is little light. Keeps in the coastal zone, in shallow water, prefers shaded places.
In the winter time it rises from the bottom and clings to the ice, this happens because there is not enough oxygen at the bottom. For feeding, however, it sinks to the bottom and is among the thickets.
Gammarus is very active, constantly in motion. The rowing legs are designed for swimming, but the walking ones are also connected. In shallow reservoirs, near the shores, the crustaceans swim on their side, but at great depth they even out and swim backwards. The movements are sharp, the body is constantly bent and unbent. If there is a solid support under the feet, then the gammarus can jump out of the water.
The constant need for fresh oxygen causes the gammarus to move quickly with its front legs to create water inflow to the gills. In females, during gestation of larvae, the clutch in the brood chamber is also washed in this way.
All its life the crayfish gammarus grows, changing the chitin crust which has become small to a new one. In the winter, molting occurs 1.5-2 times a month, and in the summer once a week.
After the seventh molt, the females acquire plates on the chest, which form the brood chamber. This chamber has the shape of a boat, the lattice surface is adjacent to the abdomen, and from the outside the gap between the plates is covered with thin bristles. Thus, there are many holes in the chamber, thanks to which fresh water always flows to the eggs.
Food gammarus is vegetable and animal food. These are mainly soft parts of plants, most often decaying fallen leaves, grass. The same applies to animal food — prefers dead remnants.
This brings some benefit to the reservoir — gammarus cleans it from harmful toxic residues. They feed on plankton. They can eat small worms, but at the same time attack them with a flock.
To feed together, if you find a large object that you can dine tightly. If the crustaceans found dead fish in a fishing net, they will easily gnaw through the tackle, along with the prey.
Reproduction and life expectancy of gammarus
Active reproduction of Gammarus occurs in spring and autumn. In the south, crustaceans have time to grow several clutches, in the north only one in the middle of summer. During this period, the male finds the female, clings to her back and helps the beloved to get rid of the old «clothes.»
As soon as the female shed, the male releases the sperm, which it smears with its paws in the brood chamber. After that, he fulfilled the functions of his father and leaves the future mother. The female lays eggs in her cell. They are quite large, dark.
The quantity reaches 30 pieces. If the water is warm, then the eggs are enough for 2-3 weeks to hatch. If the reservoir is cool, then the “pregnancy” lasts 1.5 months. The hatched larvae do not rush out, they live in the brood chamber until the first molt, and only then they leave.
With each subsequent molt in the fry the antennae are extended. Hammarus hatched in the spring by the fall are able to acquire their own offspring. And crustaceans live for about one year.
The price of gammarus as feed
Most often the crustacean of Gammarus is used as feed for aquarium fish . They also feed gammarus and turtles, snails . This is a very nutritious food, half consisting of protein. It has a lot of carotene, which provides bright colors for aquarium fish .
Of course, you can buy it at any pet store, the price of Gammarus is acceptable and depends on the manufacturer of the feed and volume. So, bags with 15 gram packages cost about 25 rubles, and when buying dried gammarus for weight, you can find a price and 400 rubles per kilogram.
Catching gammarus is not difficult, therefore, if there are suitable reservoirs in your area, you can independently provide your aquarium pet with food. It is enough to place a bundle of straw or dry grass at the bottom of the reservoir, and in a few hours to get it with mormysh stuck there, who was going to have lunch.
You can also build a net on a long stick, and get them from the bottom bundles of algae, of which then you just have to choose the crustaceans. You can save the catch in the water from which it was caught, you can wrap it in a damp cloth and put it in a cool place. But if a lot of fish and fish do not have time to eat it, it is better to dry or freeze the Gammarus for future use.