They can be described through GENOTYPE because dominant always shows through phenotype.
The lower invertebrate phylum that has the greatest diversity is called Arthropod. An Arthropod is an invertebrate animal that has a segmented body, an exoskeleton, and paired jointed appendages. Arthropods include an incredibly diverse group from the phylum Euarthropoda, which includes myriapods, <span>arachnids, insects, and crustaceans.</span>
The exchange takes place in the millions of alveoli in the lungs and the capillaries that envelop them. As shown below, inhaled oxygen moves from the alveoli to the blood in the capillaries, and carbon dioxide moves from the blood in the capillaries to the air in the alveoli. You can see more in wikipedia, or here: https://www.merckmanuals.com/home/lung-and-airway-disorders/biology-of-the-lungs-and-airways/exchanging-oxygen-and-carbon-dioxide
