The color of blood is related to the compounds that transport oxygen. Hemoglobin, containing iron, is red and is found in all vertebrates (animals having a backbone) and a few invertebrates (animals lacking a backbone). read more
The color of blood is related to the compounds that transport oxygen. Hemoglobin, containing iron, is red and is found in all vertebrates (animals having a backbone) and a few invertebrates (animals lacking a backbone). Annelids (segmented worms) have either a green pigment, chlorocruorin, or a red pigment, hemerythrin. read more
The advantage of a 4-chambered heart is that oxygenated blood and deoxygenated blood are separated, which results in more efficient respiration needed for the high metabolism of endothermic (warm-blooded) animals, and enables different pulmonary (lung) and systemic blood pressures, but is seemly over-complex for ectothermic (cold-blooded) crocodilians. read more