Discuss the evolutionary advantages for terrestrial animals

Solution

The ocean provided a nutrient rich environment free from terrestrial predators. Chasing prey into the waters is what allowed them to slowly develop longer snouts and sharper teeth for capturing fish. The earliest whales gained a huge benefit from adapting to marine life, they were entering an environment closed off to other mammals. The evolutionary forces that drove this change must have involved extreme selection pressures, due to the fact that newly semi aquatic animals could not swim efficiently and would have faced high energy demands related to necessary thermoregulation in an aquatic environment. One possible reason for transition of land mammals into water could be that water, free from large crocodiles, represented an unexploited resource. Therefore, land mammals may have begun to feed in water and then slowly adapted to better suit aquatic conditions over time. The changes in land mammals during this transition likely occurred as slow morphological changes across subsequent generations. The shift to the aquatic habitat allowed these species to exploit resources that were not available to land-based mammals, thereby reducing competition for the resources. Reduced competition allows more individuals to survive and reproduce.

There are many organisms that originate in terrestrial habitats, which have recolonized the marine environment. These organisms are called secondary marine organisms. The degree to which they become independent of the terrestrial environment varies between organisms. Some, such as mangrove trees, are restricted to the littoral fringe. Other organisms such as sea birds, sea turtles, and seals are mainly marine, but they come on shore during the reproductive season. There are also organisms that are completely land independent, including sea snakes, whales, and dolphins. Little is known about the ecological factors that caused marine organisms to invade land. However, potential reason for this transition could include biotic factors. It is known that present-day marine organisms in the upper littoral level of the rocky shores are forced into this harsh habitat by competition and/or predation.

The transition could be due to competition, terrestrial organisms are left with inadequate amounts of food. Therefore, these organisms might result to the oceans for feeding purposes. For instance, we see animals such penguins that rely on marine organism such as fish for their primary source of food and also because of the anatomical structures of these organisms. Evolution is a gradual change and not a change that happens abruptly overnight. Thus, organisms such as fish that use their gills for oxygen exchange underwater, cannot survive long on land due to the way their bodies are structured. Additionally, marine creatures do not have to worry about supporting their own weights, whereas terrestrial organisms expand approximately 40% of their energy in their movements. So if these marine creatures wanted to evolve to live on land, they would have to develop new and extensive muscles that would enable them to support their weights on land or new methods allowing them to breathe on land. Some evolutionists do say though that organisms such as the coelacanth and other similar fish are ancestors of terrestrial animals because of the “bony nature” of their fins suggesting that these bones developed into weight-bearing feet.