Anthropada Phylum
The Anthropada Phylum is the largest phylum and includes organisms such as crustaceans, arachnids, and insects. Most small anthropada such as the insects do not have a respiratory system as the oxygen can diffuse into their bodies through internal tubes and air sacs. Crustacean organisms have gills that give it the ability to breathe. Finally, the arachnids have book lungs that allow them to breathe. Most organisms under the antrhopada contain a respiratory pigment called hemocyanin that assists in transporting oxygen throughout the body. The Anthropada organisms are much like humans as they need oxygen to function and create energy for daily activities.
Crab
Much like all crustaceans, the crab requires gills to be able to breathe. The crab needs oxygen to survive, so by keeping the gills of the crab moist, they can absorb all the oxygen that they need. Once they absorb the oxygen, they release the carbon dioxide through their gills. This method of breathing allows them to roam both land and water.
Spider
The spider has two distinct organ pairs that allow it to breathe. The first organ pair that a spider can have is called the anterior pair. The second organ pair is called the posterior pair. Some spiders can have both or just one. Spiders can either have a book lung, (as seen above) which corresponds to the anterior pair or trachea, which corresponds to the posterior pair.
Fly
The fly is an insect who requires diffusion of oxygen to be present in order to survive. Oxygen enters into the fly through the spiracle and delivers the oxygen to each individual cell present in the fly. Once the fly has taken up all of the oxygen, it releases the carbon dioxide through the spiracle.