How do Human Blood Cells Differ from Animal Blood Cells?

Niki Foster
Niki Foster

Many animals, including all vertebrates, have essentially the same blood cells as humans. Other types of circulatory systems, such as those in arthropods and mollusks, are not properly blood, but do share some similarities. Humans and other vertebrates have three types of blood cells: red blood cells or erythrocytes, white blood cells or leukocytes, and platelets or thrombocytes.

Some animals have more adhesive platelets, like horses.
Some animals have more adhesive platelets, like horses.

Animals with an open circulatory system have hemolymph, a fluid combining blood and interstitial fluid, rather than blood, and it contains only one type of cell, hemocytes. Hemocytes, like the leukocytes of humans and other animals, are part of the immune system. They are phagocytic cells that ingest foreign particles and pathogens and serve in signaling within the body. Animals with hemolymph use hemocyanin instead of hemoglobin to transport oxygen.

The Rhesus Factor set of blood types.
The Rhesus Factor set of blood types.

Human blood cells are very similar to those of other animals, though there are a few interesting differences. Both human and animal blood cells can have A or B antigens, or both or neither, resulting in blood typing of A, B, O, or AB. They can also have Rhesus (Rh) antigens. All of these antigens are attached to the surface of the red blood cells.

Human red blood cells do not have nuclei, which are found in the red blood cells of many animals.
Human red blood cells do not have nuclei, which are found in the red blood cells of many animals.

Red blood cells in humans differ from those of many animals in that they do not have nuclei. Most animals, besides mammals, have nuclei in their mature red blood cells. Mature mammalian red blood cells lose their nucleus and organelles in order to carry more hemoglobin, and they do not need to use any oxygen themselves. Erythrocytes are round in all mammals except camels, who have oval erythrocytes.

Dogs and other mammals have blood cells that are very similar to humans.
Dogs and other mammals have blood cells that are very similar to humans.

Crocodile icefishes are the only known vertebrate species that do not have red blood cells or hemoglobin. They live in very oxygen-rich cold water and oxygen is freely dissolved in their blood rather than attached to hemoglobin in red blood cells. Among other animals, the size of erythrocytes can vary widely.

Platelets and leukocytes do not differ significantly between humans and other vertebrates. There are five types of leukocytes: neutrophils, eosinophils, basophil, lymphocytes, and monocytes. Humans have all five in their blood, but some animals, such as fish, have less. Leukocytes are an important part of the immune system and help to fight off disease. Platelets, which also have no nuclei, help the blood clot to prevent excessive bleeding. The platelets of different animals can be more or less adhesive; those of horses are among the most adhesive.

Animal blood can also be separated into blood type groups.
Animal blood can also be separated into blood type groups.
Niki Foster
Niki Foster

In addition to her role as a wiseGEEK editor, Niki enjoys educating herself about interesting and unusual topics in order to get ideas for her own articles. She is a graduate of UCLA, where she majored in Linguistics and Anthropology.

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Discussion Comments


Is there rh positive or rh negative in animal blood cells?


Do mammals have bone marrow?


How are our heart muscle cells different or unique from typical animal cells?


Can I use hemoglobin from rabbits or humans in mice?


Why is the size of RBCs so different among the different species of animals? Are there particular reasons for that?


Actually, most vertebrates and chondrichthyes have five types or more of white blood cells. Many fish actually will have neutrophils, lymphocytes, monocytes, basophils, eosinophils, and sometimes heterophils and they can have multiple types of thrombocytes. Invertebrates are the only ones that only have a single type of cell called a hemocyte.

The difference between humans and animals is the percentages of each type of cell and sometimes the functions. While some animals have a heterophil instead of a neutrophil, it functions similar to a mammalian neutrophil in the immune system.


Interesting article but it tried to explain too much at once. I feel the person who authored the article is very bright but they did not do a good job of sticking to the question at hand. Many facts, few connections.


I found this article very informative. Thanks to the author and knowledgeable respondents.


What is the difference between the blood cells of aves and reptiles?


@ Babalaas- There are blood substitutes available, but they are not approved for use by the general population in the United States. This is mostly because of the increased risk of death and heart attack in patients who have received synthetic blood.

In clinical trials, the death rate is 30% higher in those who received synthetic blood. The recipients of synthetic blood are also about three times more likely to suffer from a heart attack.

As for xenotransfusion and xenotransplantation, I am not sure if researchers have successfully performed the procedures. I do know that researchers are trying to develop the procedures, and that the FDA regulates the procedures.


Are there any substitutes for human blood? Can pig blood, or any other type of animal blood, be used in certain situations as a blood substitute for transfusion purposes?


@ Anon68877- All vertebrates have white blood cells (or leukocytes). The difference between human white blood cells and animal white blood cells is the number of cells present. Humans have five different types of leukocyte cells present in their blood while most vertebrates have less. The types of leukocytes present are of the same five varieties as the five found in humans. The bone marrow produces all leukocyte cells in vertebrates.

Invertebrates on the other hand do not have white blood cells or blood for that matter. Invertebrates do not have a closed circulatory system like we do, instead they use hemolymph suspended in interstitial fluid to distribute oxygen and other alimental substances to their bodies. This would be the gooey insides of a crushed invertebrate.


Do animals have white blood cells?

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