The developmental stages that a fish undergoes to reach adulthood are divided into embryonic and postembryonic periods. You can designate them as stages of eggs and fry. These two processes are interconnected, and the structure of the fish larva naturally depends on the structure of the embryo. Thus, it will be logical to start from the moment of fertilization of the egg with sperm - with which the development of living organisms begins.
Ikrinka is a fry in the future
The stage preceding the development of the larva is the caviar stage. In fish, most often external fertilization, that is, the female lays (spawns), and the male fertilizes it with milk. However, in some species, for example, cyprinids: pecilia, guppy, internal fertilization, and the female, after reaching the development of eggs, sweeps already formed fry. The first time the larva develops depends on what the egg is. If at the initial stages the fish will exist in an environment poor in nutrients, caviar, as a rule, will be increased in size. This gives the fry an advantage in the form of a supply of nutrients in the yolk sac (located on its abdominal part).
It happens that fish spawn in quiet backwaters, away from strong currents and predators, in order to preserve future offspring. But in standing and warm reservoirs oxygen dissolves worse. In order to avoid oxygen starvation, a pigment (usually a carotenoid type) develops in the calf, it allows you to save and accumulate oxygen to the larva. If caviar does not have breathing problems, it is more often transparent - so it is less noticeable in the water column. As a protection for offspring, eggs have many solutions. Caviar can be sticky, cling to plants and natural shelters. It can be small and inconspicuous or vice versa, large, flooded, easily floating in streams of water.
Fish fry are fish larvae . Their structure.
In the normal development of a living organism, a male emerges from the fertilized fish roe. So, what is this anatomical malek, what are its structural features? It is a larva of fish. On its ventral side you can see the yolk sac. Fins are not yet divided into paired and unpaired. The development of the digestive system has not fully occurred. Of course, the gonads, the gonads, are not developed. In the juvenile period, a characteristic body covering develops: scales. Subsequently, there is a gradual development of all organs and systems in the image of an adult.
Development features
This period is characterized by the greatest linear and weight growth of the body. The development rate even within one species can vary significantly and depends on temperature, light, nutrition. For example, if the illumination and temperature are greater and there is enough food, then reaching puberty and developing fish will go much faster due to the acceleration of metabolic processes.
At first, the fry is fed by the material of the yolk sac. Then he becomes able to eat crustaceans from plankton: daphnia, cyclops, etc. To pass to the nutrition characteristic of adult fish, some time must pass.
During development, the larva may change. Malek is a transitional form to an adult. For example, in a flounder it has first two-sided symmetry, and then the body is divided into two sides: the upper and lower. The eye goes to the upper side. In European snake-shaped eel, the larva initially has a shortened body. And then it becomes like an adult body.
Fish offspring care
The survival strategies for each species are different. There is only one common goal: to leave as many offspring as possible, but you can go to it in different ways. There is a strategy - to lay as much eggs as possible: for example, Atlantic herring can sweep 100,000 eggs. More likely, out of this number of eggs, at least some individuals will survive.
You can lay a small number of eggs, but all of them are courted. For example, tilapia carries eggs first, and then the cubs in its mouth. It has already been said above about viviparous fish that toss a small number of already formed larvae. Seahorses hide their offspring on the body. These are fry that are more likely to survive, which means the amount of spawned eggs can be reduced.