Most animals in nature differ in terms of nutrition, reproduction, growth characteristics and offspring care. All animals have different life cycles. The birth, growth, development, reproduction and death of living things in nature are called life. The life cycle begins with mating and reproduction. Reproduction in animals, like humans, occurs when the sperm fertilizes the egg. In animals, the union of the nuclei of male and female reproductive cells is called fertilization, and the egg that emerges as a result of fertilization is called fertilized egg. After the zygote is formed, the embryo is the first stage of the living thing. The embryo forms a new animal by completing its development. In order for the embryo to grow and develop, it must be well fed and well protected. For this, a good and suitable environment must be provided for the embryo.
Fertilization Types in Animals:
- External Fertilization
- It is formed by the union of sperm and egg outside the body, in water. In order to increase the chance of fertilization, these creatures also lay large numbers of eggs in the same place. The development of the embryo resulting from fertilization occurs in a lake or other water source. It occurs in fish, frogs and aquatic invertebrates.
- Internal Fertilization
- It is the union of sperm and egg cells in the mother’s body. In the event of internal fertilization, male individuals produce more sperm and female individuals produce a small number of egg cells. Internal fertilization has a greater chance of external fertilization. It is seen in reptiles, aquatic and terrestrial mammals, humans and many living things.
Animals and spesifications :
According to whether the animalshave a skeletal system or not; They are examined in two groups as vertebrate and invertebrate animals.
Animals with a skeletal system are called vertebrates. Vertebrates in their own group; They are divided into five groups as fish, frogs, reptiles, birdsand other mammals.
Vertebrates of all kinds;
- There are skeletal systems
- They reproduce by fertilization.
- They reproduce by laying eggs or giving birth as a result of fertilization.
- closed circulation is seen in the blood systems. (Blood circulating in veins only).