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External fertilization is a mode of reproduction in which a male organism's sperm fertilizes a female organism's egg outside of the female's body. [1] It is contrasted with internal fertilization , in which sperm are introduced via insemination and then combine with an egg inside the body of a female organism.
Depending on the animal species, the process can occur within the body of the female in internal fertilization, or outside in the case of external fertilization. The fertilized egg cell is known as the zygote. [2] [5] To prevent more than one sperm fertilizing the egg , fast block and slow block to polyspermy are used. Fast block, the membrane ...
Male giant water bug Abedus indentatus with eggs on his back. Outside the Hymenoptera, parental care is found among the burying beetles and the magnificent salt beetle. [35] Many species of Hemiptera take care of their young, for instance in the Belostomatidae genus Abedus. [citation needed] Among arachnids, several groups exhibit parental care.
In all cases, the eggs are protected until they hatch and the fry become free swimming. Only in some cases does the parent extend protection to mobile juveniles. Among the cichlids and arowanas, extension of brood care to the fry is common, and they have behavioural cues to tell fry swimming and feeding away from the parent that danger is ...
First, external fertilization protects against paternity loss; however, sneaker tactics and strong sperm competition have evolved many times. Second, the earlier release of eggs than sperm gives females an opportunity to flee; however, in many paternal care species, eggs and sperm are released simultaneously.
A new study says it may have been because of their eggs and a long incubation period. ... finds that some dinosaur eggs may have taken six months or more to hatch–much longer than the eggs of ...
If, in this transit, it meets with sperm, the egg selects sperm with which to merge; this is termed fertilization. The fertilization usually occurs in the oviducts, but can happen in the uterus itself. The zygote then implants itself in the wall of the uterus, where it begins the processes of embryogenesis and morphogenesis. When developed ...
Using the Water Test to Determine an Egg's Freshness. When you’re dealing with an older egg that looks fine on the outside, and you want to avoid a big stink, try this: Place your egg in a glass ...