Question

1. Compare the the respiratory surfaces of a marine worm, a planarian flatworm, a ray-finned fish, an insect, a mammal, and a bird. Which is most efficient and why? Which challenges are their respiratory systems adapted for?

Answer 1

In marine worm, oxygen diffuses through the body surface and goes inward to a network of capillaries which is under the body surface. In planarian flatworms, the surface area is increased because of the flat shape, all the cells remain close to the membrane surface ensuring that they have access to oxygen. In ray-finned fish, blood capillaries of the gill filaments remain close to the gill surface, so that they can take up more oxygen and give up excess CO2 in the water. In insects, spiracles act as muscular valves, forming an internal respiratory system. In mammals, respiratory surfaces are linings of the lungs, gas exchange occurs through the air sacs or alveoli. In birds, expansion or contraction of the lungs does not take place, gas exchange occurs through air capillaries.

Respiratory surfaces of a bird is the most efficient. An efficient respiratory surface is composed of abundant capillaries. They have hundreds of tiny, branching air capillaries that transfer more oxygen with each breath. Along with this, their thin, tubular body shape also contributes to an efficient respiratory surface.

Their respiratory system is adapted for supplying a lot of oxygen, as the most amount of energy is consumed in flying, they require additional oxygen for their metabolic processes.