Question

The similarities in early structures in developing fish,birds,and humans

Answer 1

While fish, birds, and humans are vastly different in many ways, there are some similarities in their early embryonic structures.

In all three groups, the early embryo goes through a process called gastrulation, where the single-layered ball of cells that formed after fertilization transforms into a three-layered structure. These three layers are called the endoderm, mesoderm, and ectoderm, and they give rise to different organs and tissues in the body.

During gastrulation, a primitive streak forms along the dorsal (back) side of the embryo, which establishes the axis of symmetry and determines the orientation of the body. This primitive streak is a key feature in all three groups, and the formation of it is similar in all of them.

Additionally, all three groups initially develop structures called pharyngeal arches, which are a series of pouches that form on either side of the embryo's developing head. These structures give rise to various structures in the face and neck region, such as the jaw and ear in humans, and the gills in fish and some amphibians.

While these similarities are present in the early stages of development, each group eventually diverges and develops their own unique features and adaptations that allow them to survive and thrive in their respective environments.

Answer 2

Thay look very similar and it is often difficult to tell them apart.

Many traits of one type of animal appear in the embryo of another type of animal.

For example, fish embryos and human embryos both have gill slits. In fish they develop into gills, but in humans they disappear before birth.