Question

compare and contrast gas transportation systems of cnidarians, flatworms, mollusks, annelids and arthropods.

Answer 1

Gas transportation system of Cnidarians: They exchange gases using the process of diffusion. They have a cavity which is known as a gastrovascular cavity. In Cnidarians, this gastrovascular cavity is called the coelenteron. So, during diffusion, oxygen in the outside surrounding environment diffuses through the skin of the Cnidarian into the inside of the Cnidarian.This happens when the water is pumped in and out of gastrovascular cavity. And this absorbed gas is transported to other cells via a special structure knoiwn as mesoglea because there is no circulatory system in Cnidarians.

Gas transportation system of flatworms: Flatworms also use the process of diffusion to absorb oxygen from the surrounding environment across their surface membranes. The flatworms are literally flat! They are less than 1 mm in diameter. Their cells are kept moist to facilitate the process of diffusion. This absorbed oxygen is also transported by diffusion because they also doesn't have the circulatory system.

Gas transportation system of mollusks: In mollusks there is an organ called the gill filaments to do the job. It is located on the edge of the mantle and act as a barrier between the body's blood and water or air whatever may be which is outside of the body. The oxygen and carbon dioxide is exchanged througfh the gill filaments.They have an open circulatory system. Their blood reaches everywhere on the body and gases are exchanged.

Gas transportation system of annelids: The annelids doesn't have a specific respiratory system in their body. So, they exchange gas through a structure called capillary beds. The capillary beds are present on the epidermis of the annelids. The capillary beds takes gases from the surrounding environment and pass it into the blood of the annelids.

Gas transportation system of arthropods: The terrestrial arthropods possess a respiratory system with tracheae and a specila structure called booklungs. But the aquatic arthropods have gills. The tracheae are teeny tyny tubes which allows passing of gases into interiors of the body of arthropods. The endings of these tubes reach tissues or the tubes are immersed with blood paasing. So, eitherway, the gas exchange takes place. Having an open circulatory system, the gas reaches or transported to various parts of the body of the arthropods.

So, they all have the process of diffusion in them. But some of them have specific structures designed for the gas exchange.