On Earth, the blood of most animals is red, which is due to the presence of an iron-containing protein called hemoglobin. Hemoglobin binds to oxygen, giving blood a red color while delivering oxygen to all parts of the body. However, there are some unusual animals on Earth whose blood is not red, but blue.
First of all, we need to understand why the blood of animals is usually red. When the iron in hemoglobin is combined with oxygen, it absorbs and rereleases energy to provide the body with essential nutrients. The hemocyanin in blue blood contains copper, which appears blue when combined with oxygen. This blue blood is similarly able to carry oxygen, but works slightly differently than hemoglobin.
So, which animals have blue blood?First of all, we think of octopus and cuttlefish. These cephalopods have a unique hemocyanin, and their blood is indeed blue. In addition to this, there are some marine creatures such as horseshoe crab (hòu) that also possess blue blood. Horseshoe crabs are ancient creatures that are rich in copper in their blood, hence their blue color.
Why is the blood of these animals blue?Actually, it has to do with their evolutionary process. These animals live in a marine environment rich in copper, for which copper is an important nutrient. Over a long period of evolution, their bodies have adapted to this environment and developed the ability to synthesize hemocyanin from copper.
Hemocyanin differs from hemoglobin in some ways of working together. Hemoglobin is widely used in most animals because of its ability to deliver oxygen more efficiently. However, in certain environments, such as the deep sea or caves, animals are unable to synthesize hemoglobin due to lack of light or iron. In this context, some animals have evolved the ability to synthesize hemocyanin from copper in response to changes in their environment.
In addition to octopuses, cuttlefish, and horseshoe crabs, there are a few other animals that also have blue blood. For example, the blood of some snails and crustaceans is also blue. These animals also live in copper-rich environments, so their bodies have adapted to the synthesis of hemocyanin from copper.
After learning about these animals with blue blood, we can't help but ask: why do most animals have red blood?In fact, this is mainly because of the high efficiency of hemoglobin in transporting oxygen. The iron in hemoglobin binds oxygen molecules more closely, making it easier to transport to all parts of the body. In addition, hemoglobin is also able to release stored oxygen in the event of a lack of oxygen in the body, which is essential for the life maintenance of animals.
In conclusion, while there are some animals on Earth that have blue blood, most animals still have red blood. This is mainly because of the high efficiency of hemoglobin in transporting oxygen and its important role in life support. And those animals with blue blood show us the diversity and adaptability of biological evolution.