{
  "id": 17217995,
  "title": "The Bloody Palette of the Animal Kingdom Goes Far Beyond Red. These Creatures Have Blood That Runs a Chilling Blue, Bright Green or Milky White",
  "url": "https://urgent.news/2026/10/30/the-bloody-palette-of-the-animal-kingdom-goes-far-beyond-red-these",
  "topic": "science",
  "section": "Science",
  "published": "2026-10-30T11:30:00.000Z",
  "source": {
    "name": "Smithsonian",
    "slug": "smithsonian",
    "url": "https://www.smithsonianmag.com/science-nature/the-bloody-palette-of-the-animal-kingdom-goes-far-beyond-red-these-creatures-have-blood-that-runs-a-chilling-blue-bright-green-or-milky-white-180989752/"
  },
  "original_language": "en",
  "account": "The colors that flow within a creature’s body can differ vastly from the familiar red of human blood, according to scientists studying the mysteries of blood. While the red shade of human blood is owed to hemoglobin, which is rich in iron atoms that bind to oxygen, animals have evolved a myriad of alternative pigments to carry out this life-sustaining task. Some creatures, like octopuses and crustaceans, rely on a copper-based protein called hemocyanin that turns blue when oxygen is attached. Meanwhile, brachiopods and peanut worms showcase a purple hue due to an iron-rich protein pigment called hemerythrin. The greenish-yellow blood of sea squirts is thought to be the result of vanadium concentration or carotenoid production from their diet. New Guinea lizards undergo a transformation, converting hemoglobin into the green pigment biliverdin, which takes over the blood’s coloration. Notably, Antarctic blackfin icefish defy the norm entirely, lacking hemoglobin and blood cells entirely. Instead, they rely on oxygen diffusing directly into their transparent bloodstream. This unique adaptation allows them to survive in frigid conditions by minimizing energy expenditure, as they are patient ambush predators. The evolutionary journey of icefish to shed their red blood cells and hemoglobin remains a mystery, but researchers speculate that the abundant oxygen in their environment may have rendered hemoglobin unnecessary. The bizarre hues of blood shed light on the astonishing diversity of life on Earth, with implications for human health as well. For instance, the high-altitude adaptations of certain mammals could inspire therapies for altitude sickness and anemia.",
  "summary": "The hemoglobin in humans’ blood is not the standard for all critters—and one group of Antarctic fish are the only vertebrates to not have red blood cells at all",
  "key_points": [
    "Some animals have blue blood due to copper-based hemocyanin.",
    "Others exhibit greenish-yellow blood from vanadium or carotenoids.",
    "Antarctic icefish lack hemoglobin and blood cells entirely."
  ],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}