Whales are closely related to hoofed mammals with an even number of toes, such as horse, because they evolved from them. Before whales were what we know them as today, they were relatively similar to horses. They used the water to flee from predators, and they evolved slowly to heighten their swimming ability, eventually becoming modern day whales. Fish have always been aquatic animals that have gills. Whales cannot breathe underwater, so they take in oxygen the same way a horse does. Also, both horses and whales are mammals that give birth to their offspring and are warm-blooded. Fish lay eggs and are cold-blooded.
Different substances such as growth factors and nutrients affect the mechanism of density-dependent inhibition of growth as cells become more and more numerous
