Here's one: octopuses have three hearts and blue blood.
Two of the hearts pump blood to the gills, while the third pumps it to the rest of the body. That third heart actually stops beating when the octopus swims, which is part of why they prefer crawling—swimming exhausts them.
The blue blood comes from a copper-based protein called hemocyanin (instead of the iron-based hemoglobin in human blood), which is more efficient at transporting oxygen in cold, low-oxygen environments like the deep ocean.
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Here's an interesting one:
Octopuses have three hearts and blue blood. Two hearts pump blood to the gills, while the third pumps it to the rest of the body. Their blood is blue because it uses a copper-based molecule called hemocyanin to carry oxygen, instead of the iron-based hemoglobin that makes our blood red. Copper-based blood is actually more efficient at transporting oxygen in cold, low-oxygen environments—like the deep ocean—which is likely why it evolved this way.
Bonus weird fact: when an octopus swims (rather than crawls), one of its hearts actually stops beating, which is part of why they tend to prefer crawling—swimming exhausts them faster.
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Here's one: octopuses have three hearts and blue blood.
Two of the hearts pump blood to the gills, while the third pumps it to the rest of the body. That third heart actually stops beating when the octopus swims, which is why they prefer crawling and tend to get tired quickly when swimming—it's energetically costly for them.
The blue blood comes from a copper-based protein called hemocyanin (instead of the iron-based hemoglobin humans use). Hemocyanin is less efficient at transporting oxygen than hemoglobin, but it works better in cold, low-oxygen environments—handy if you're a creature often lurking in deep, chilly ocean water.
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