Explain how certain physical laws constrain an animal's size and shape. Explain how these laws illustrate convergent evolution in organ systems (ex/ epithelia, digestion, nervous, muscle). Give an example.

Explain the laws and how they link to size and shape. Link this to an example of convergent evolution.

 

• Explain how certain physical laws constrain an animal's size and shape. Explain how these laws illustrate convergent evolution in organ systems (ex/ epithelia, digestion, nervous, muscle). Give an example.

Animals vary in their form and function as each animal has their own unique body plan. This body plan dictates the limitations in size and shape of various animals. The physical laws determine the strength, diffusion, movement and heat exchange. Locomotion also depends on shape. For instance, animals with bilateral symmetry and lives in water tends to have a fusiform shape. This shape allows them to swim at high speeds in the water by decreasing the drag on the body as it moves. Since the properties of water affects the movement of swimming animals, they must be able to adapt by limiting possible shapes.

In relation to the organ systems, every cell require an aqueous environment to be able to exchange nutrients and wastes. Thus, membrane structure depends on aqueous solution inside and out and the process of diffusion across membranes between aqueous solutions. The animal's body shape and structure are formed to allow exchange with the environment across wet membranes by different mechanisms.

For instance, in Hydra cells, exchange occurs directly inside and out while for flat planaria, they have enough surface close to its cells to allow exchange. Other organisms have gills/lungs for gas exchange, have digestive system for breakdown, absorption, and elimination, as well as excretory system to eliminate nitrogen waste.

Diffusion also is effective over a specific distance and limits the size that an individual cell can attain. With a small cell like an amoeba, exchange of waste and nutrients through diffusion occur effectively unlike those larged-size cells.

As animals increase in size, thicker skeletons are required for support. Meanwhile, animals with smaller body size have higher metabolic rate. Hence, smaller animals lose more heat and therefore need to eat more to obtain lost energy. The convergent evolution results in similar adaptions of diverse organisms facing the same challenge to be able to function optimally and survive.