Oviparity is a form of reproduction in animals, where the female lays eggs, which are then fertilized externally by the male. The eggs are typically laid in a nest or on the ground, and most species of animals, including amphibians, reptiles, birds, and fish, use this method of reproduction. Though oviparity is the most common form of reproduction, some species of animals, such as mammals, do not oviparous.
The development of an egg into a live animal is a complex process that involves the fertilization of the egg, the formation of an embryo, the formation of a protective shell, and the hatching of the egg. Once an egg is laid, the female’s role in the process is complete, and it is up to the male to fertilize the egg. This is usually done by releasing sperm into the water near the egg, or by depositing sperm directly onto the egg.
If the egg is not fertilized, the egg will not develop into an embryo, and will eventually die. If the egg is fertilized, then the embryo begins to develop. This process varies depending on the species, but typically involves cell division and cell differentiation. This is the process by which the cells of the embryo become specialized and form the various tissues and organs of the organism.
Once the embryo has developed, it must be protected until it hatches. This is done by forming a protective shell around the egg. The shell is made of a material called chorion, which is secreted by the female. The shell helps to protect the embryo from predation and other environmental hazards, and also helps to regulate the temperature of the egg, as well as the amount of water and oxygen that can pass through it.
Finally, the egg hatches. This is usually done by the embryo absorbing the water contained within the egg, which causes it to swell and eventually break free from the shell. Once the embryo has hatched, it is considered a mature animal and is capable of surviving and reproducing on its own.
In conclusion, oviparity is the most common form of reproduction in animals, and involves the female laying eggs, which are then fertilized by the male. The egg then undergoes a complex process of development, and is protected by a hard shell until it hatches. Once the egg has hatched, the embryo is considered a mature animal and is capable of surviving and reproducing on its own.
References
Cummins, J. (2015). Animal Reproduction. Britannica. https://www.britannica.com/science/animal-reproduction
Mader, D. (2011). Biology. McGraw Hill Education.
Schuster, G. (2013). Oviparity and Viviparity. Merck Veterinary Manual. https://www.merckvetmanual.com/reproduction-and-development/reproduction-in-vertebrates/oviparity-and-viviparity