Silver crucian carp is a type of crucian carp that lives in cold temperate waters. The way it reproduces is unique. The number of chromosomes in silver crucian carp is triploid, that is, each somatic cell contains 162 chromosomes. The number of chromosomes in the eggs they produce does not decrease by half and is still 162. While each chromosome of ordinary crucian carp contains 100 chromosomes, the chromosomes in their eggs and sperm are halved to 50. During fertilization, after the sperm enters the egg, a diploid fertilized egg containing 100 chromosomes is formed.
When silver crucian carp reproduces, the egg must have sperm from other male fish to stimulate its development. However, the sperm definitely does not participate in the actual fertilization process. It only acts as a catalyst and does not impart any genetic information to the egg. The egg is activated by the sperm and further divides itself to develop into offspring identical to the mother. Therefore, the offspring of silver crucian carp are all female individuals that are exactly the same as their mothers from external morphology to internal structure, thus forming a "female family" in the fish kingdom.
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