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How do Human Blood Cells Differ from Animal Blood Cells?

Niki Acker
Updated: Mar 03, 2024

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.

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.

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.

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.

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.

The Health Board is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Niki Acker
By Niki Acker
"In addition to her role as a The Health Board editor, Niki Foster is passionate about educating herself on a wide range of interesting and unusual topics to gather ideas for her own articles. A graduate of UCLA with a double major in Linguistics and Anthropology, Niki's diverse academic background and curiosity make her well-suited to create engaging content for WiseGeekreaders. "
Discussion Comments
By anon995290 — On Apr 18, 2016

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

By anon979562 — On Nov 27, 2014

Do mammals have bone marrow?

By anon933043 — On Feb 14, 2014

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

By mahmoua — On Feb 10, 2013

Can I use hemoglobin from rabbits or humans in mice?

By anon312806 — On Jan 09, 2013

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

By anon280675 — On Jul 19, 2012

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.

By anon158985 — On Mar 09, 2011

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.

By whitewater — On Mar 09, 2011

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

By sulaxana — On Aug 05, 2010

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

By Georgesplane — On Jul 20, 2010

@ 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.

By Babalaas — On Jul 20, 2010

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?

By aplenty — On Jul 20, 2010

@ 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.

By anon68877 — On Mar 04, 2010

Do animals have white blood cells?

Niki Acker
Niki Acker
"In addition to her role as a The Health Board editor, Niki Foster is passionate about educating herself on a wide range...
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