Usually in most animals the color of the blood is deep red. This is due to a certain type of protein called “Hemoglobin”. However, if a different type of protein is present in the blood, animals can have a different color of blood.
These varieties in the colors of blood can be identified with the protein molecules that carry oxygen to the blood. After the deep red color, blue color blood is found in many organisms.
This phenomenon of blue blood in certain animals is due to the presence of a copper-based molecule called “Hemocyanin” in their circulatory system. Hemocyanin contains copper ions rather than iron like we humans have in our own “Hemoglobin”. Thus, it helps in giving it a blue color when oxygenated.
List of 10 Animals With Blue Blood Color:
1. Octopus
- Scientific Name: Octopoda
First animal with blue blood on our list is Octopus. The blue blood of octopuses is not only an interesting biological feature but also serves a crucial function in their survival in diverse marine habitats such as Efficient Oxygen Transport, Cold Tolerance, Pressure Tolerance, Color Changes and Camouflage.
The use of hemocyanin in octopuses is an adaptation to their marine environment, where oxygen levels can vary depending on regions and depth. Hemocyanin is more efficient than hemoglobin at extracting oxygen from seawater under lower oxygen pressures.
Octopuses also have other unique traits like:
- 3 Hearts,
- 9 Brains,
- Regenerative Abilities, etc.
2. Horseshoe Crab
- Scientific Name: Limulidae
Another animal on our list with blue blood is Horseshoe Crab. This distinctive blue color results from copper-based molecules called Limulus amebocyte lysate (LAL), which reacts to bacterial endotoxins such as Lipopolysaccharide.
Horseshoe crabs have an open circulatory system, which means that their blood, also known as hemolymph, directly flows over the organs and tissues without being confined to vessels as in closed circulatory systems like humans.
Horseshoe crab blood plays a vital role in pharmaceutical testing, ensuring vaccines and medical devices are free from contamination. Apart from its medicinal value, these ancient arthropods have roamed the Earth for some 450 million years, predating dinosaurs.
3. Spiders
- Scientific Name: Araneae
Spiders are one of the few creatures that possess a unique and fascinating feature – blue blood. Hemolymph in spiders functions similarly to blood in vertebrates, transporting nutrients and oxygen throughout their bodies. The blue color results from the copper ions binding to oxygen, providing these arachnids with this different biological trait.
Regarding the blue blood of spiders, it’s not typically harmful to humans. Spider blood, or hemolymph, does not contain toxins that pose a threat to humans. In fact, handling spiders or coming into contact with their hemolymph is generally safe. However, the primary concern with spiders is their bites, which can vary in effects depending on the species.
4. Frogs (Certain Species)
- Scientific Name: Trachycephalus resinifictrix
Like most vertebrates, frogs have red blood.But there are some species like “Mission golden-eyed tree frog” which have blue colored blood. Due to the presence of high levels of the bile pigment biliverdin, and their translucent skin shows off their inner organs and structures like blue blood, bones, and muscles.
Most of the Amazon frogs are poisonous, but the Amazon milk frogs are not as poisonous to humans. Although milk frogs can be poisonous to their predator, when threatened or stressed. They release secretions for protection against these predators.
5. Squid
- Scientific Name: Teuthida
Next animal with blue blood on our list is Squid. The difference between squid and octopus is that the squid have longer bodies, longer tentacles with suckers along the entire length, while octopuses have shorter bodies and arms.
Just like the octopus, squids also have blue colored blood. Squids have an open circulatory system. Their blood, containing hemocyanin, pumps through vessels and bathes organs directly in a cavity.
Squids also have some unique traits like regenerative abilities, large brains, bigger size (up to 43 feet), etc.
6. Lobster
- Scientific Name: Nephropidae
Another animal with blue blood on the list is Lobster. Snails also have Hemocyanin, a copper-based molecule, which serves as the respiratory pigment, turning blue when oxygenated.
Usually the Lobster blood is colorless. When exposed to oxygen, it develops a bluish color.
Lobsters also undergo the process of molting.During molting, when lobsters shed their exoskeleton to grow, their circulatory system plays a crucial role. The process requires an influx or rush of hemolymph to expand the new exoskeleton and makes it easier to get rid of the old one.
7. Cuttlefish
- Scientific Name: Sepia officinalis
Cuttlefishes are one of the certain animals that are noted for the unique color of their blood— blue/green. They have a closed circulatory system, which means that the blood circulates within vessels and is separate from the surrounding tissues.
Cuttlefish have three hearts: two branchial hearts and one systemic heart. The 2 branchial hearts are responsible for pumping blood through the gills, where oxygen is obtained and carbon dioxide is released. The systemic heart then pumps oxygenated blood to the rest of the body.
8. Snail
- Scientific Name: Gastropoda
Snail is the next animal with blue blood on our list. The blood color of the snail is blue due to the presence of the pigment called Haemocyanin. Snails have a less complex circulatory system compared to higher vertebrates.
Their circulatory system is open, meaning that the blood, also known as hemolymph, directly flows over the organs and tissues rather than being confined within blood vessels like humans.
Snails possess a simple tubular heart, often located near the top of the body. This heart pumps the hemolymph into the open circulatory system of theirs. Hemolymph not only serves as a blood and as a means of transporting nutrients and waste throughout the body..
9. Prawn & Shrimp
- Scientific Name: Dendrobranchiata & Caridea
Prawn & shrimp are two different creatures. But they are both decapods and look quite identical too. They have an open circulatory system and have a tubular heart located dorsally in the thorax. The heart pumps hemolymph into the hemocoel, which is the body cavity that surrounds the body organs.
Depending on their species, the color of their hemolymph can range from a bluish-green to a bright blue color. Both prawns and shrimp have evolved similar circulatory systems to support their active and aquatic lifestyles in marine and freshwater environments.
10. Scallops
- Scientific Name: Pectinidae
Scallops belong to the family Pectinidae and are bivalve mollusks, which means they have a two-part hinged shell. Scallops have an open circulatory system, which is a common feature among mollusks. In the open circulatory system, blood does not need vessels to transport oxygen, nutrients, etc.
Scallops is one of the other animals with blue blood, that we have mentioned in this article. The blue coloration of the blood (hemolymph) occurs when the scallop extracts oxygen from the water through its gills.
Scallops are not the fast swimmers, but they can propel themselves by rapidly clapping their shells together. This action creates a jet of water that propels them forward in the water, allowing them to escape from predators.
11. Clams
- Scientific Name: Bivalvia
And the last animal with blue blood on our list is Clams. Clams have an open circulatory system with the fluid hemolymph, which serves functions similar to both blood and interstitial fluid. It circulates through the body cavity of the open circulatory system.
Clams have a two-chambered heart, which is a simple muscular structure that pumps hemolymph into the hemocoel (body cavity containing circulatory fluid). The heart is located near the hinge of the clam’s two shells.
lams have been around in this world for a very long time. Fossilized clam shells have been found dating back hundreds of millions of years, indicating their ancient lineage.