FISH DEVELOPMENT

 

The beginning of the fish life cycle begins with the egg (ova) that has been successfully fertilized. After the egg is fertilized, an embryo is formed so that this is where the life characteristics of an individual organism begin. At this stage the metabolic process takes place. Cells begin to divide.

Fish reproduce externally. In doing so, male and female fish will approach each other, then the female fish will issue eggs. Then, the male fish will release his sperm, the sperm and eggs will mix in the water (which is called oviparus).

Fish Life Cycle

1. Eggs

The beginning of the fish life cycle begins with the egg (ova) that has been successfully fertilized. After the egg is fertilized, an embryo will be formed so that this is where the life characteristics of an individual organism begin.

At this stage the metabolic process takes place. Cells begin to divide. In addition, tissues and organs begin to form until finally the eyespots and tail begin to appear inside the egg.

Next, the tail will wrap the egg around the head. And when the hatching time has finished, the embryo tail will come out of the shell. The embryo turns into a larva that swims freely in the water.

 

2. Larva

Larva is the name for hatched fish. The characteristics of the newly hatched larvae are having a yolk sac. The yolk serves as a source of nutrition for several days before they can eat live prey.

This process of eating egg yolk can last for 2-4 days, which is then known as endogenous eating. After the larva's mouth is formed and the eyes begin to develop, the larvae can eat organisms or particles in the water which is called exogenous eating.

3. Adult Fish

This is the end of the larval stage. Where the characteristics of adult fish have begun to appear. Such as body features, color, fins, full organs, and so on.

The developmental process of the phases above is influenced by internal (physiological) and external (environmental) factors. These two factors contribute to the development of the fish, from eggs to adulthood.

Either become an adult female that produces mature eggs that are ready to be fertilized or ova or male eggs that secrete spermatozoid. This spermatozoid is useful for fertilizing eggs.

Fish life cycle: Basically the life cycle conditions can be called the life cycle. Surely every living thing has a life cycle that is not the same. Usually it depends on the type of living thing itself. This also applies to fish. Fish are vertebrates that inhabit water areas.

Fish can be found in many places with different types and names. Broadly speaking, fish are divided into two types, namely freshwater fish and sea water fish. Both can be distinguished from the animal tissue they contain. Even so, broadly speaking, these two types of fish remain the same. Fish are categorized as imperfect metamorphosis.

The life cycle of a fish is fairly simple. From eggs to adult fish.

Fertilization The beginning of a development is the fusion of the ovum nucleus and sperm nucleus. The fertilization process in fish is monospermic, that is, only one spermatozoa will pass through the micropyle and fertilize the egg. In the process of fertilization, spermatozoa enter the egg through the micropyle holes found in the chorion. Each spermatozoa has the same opportunity to fertilize one egg. However, because the space where fertilization occurs, namely the meeting of the egg with spermatozoa in oviparous fish is very large, the chance for the spermatozoa to meet the egg is actually very small. Under optimum conditions, the fish spermatozoa that have just been released from the body have the power to move in water for 1-2 minutes.

Relatively, the egg layer that has been in water is hard and cannot be penetrated by spermatozoa except through the micropyle which looks like a funnel. The large funnel hole is located on the outside and the small hole is on the inside. The hole is so small that it is impossible for more than one sperm to pass through at a time. When the spermatozoa enters the funnel hole, it becomes a plug for the others and after the spermatozoa's head enters, the tail slips off. Thus, fertilization in fish is generally monosperm, where when one spermatozoa has entered the micropyle will quickly change.

 

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