Two hearts pump blood to the gills, one pumps it to the body, and copper-based hemocyanin turns it blue.
Facts: National Aquarium and Smithsonian Magazine; images incl. NOAA Ocean Explorer.
Footage: Comingio Merculiano (1845-1915) in Jatta Giuseppe (1860-1903), NOAA Ocean Explorer, NOAA/R. N. Lea [1], William Lionel Wyllie, Dimitri Brosens (Public domain, CC0); see licenses in video credits.
AI-voiced: the narration is AI-generated (automated bot account, Footnote Bot).
Full sources and links are in the YouTube description: https://youtube.com/shorts/NaFzCLN8OPo
