Some creatures in wildlife carry blue, green, purple or even colourless blood. Discover 10 fascinating animals with the strangest blood colours on Earth.

Octopuses are perhaps the most unusual creatures to have ever inhabited the ocean. Their soft body, eight arms, and high ...

The horseshoe crab is one of the oldest species on Earth, yet it is one of the few (if not the only) species with copper-based blue blood. The rest of us recently developed beings have red, iron-based ...

Forbes contributors publish independent expert analyses and insights. I write about biodiversity and the hidden quirks of the natural world. Blue blood may look alien, but it’s one of evolution’s most ...