Define homologous structures and explain how these structures support evidence of common ancestry

Homologous structures are framework where the parts of the body is similar in structure to different species of common ancestry. The way structures develop in embryos and the pattern in which they appeared over evolutionary history. In addition, the evidence of this common ancestry can be seen in the structure and development of these homologous structures, even if the existence of these structures adapted to different function as the result from a collective ancestry.

Pancreassalivary glandsliverlachrymal glandssweat glandoil glandsgoblet cells

In some developing nations the percentage of the animal protein from fish in the diet can be as high as 25 percent.  about 85% of fish caught is used for human consumption.  the remainder is converted into fishmeal and fish oil.