OCTOPUSES
Octopuses have three hearts
Octopuses have three hearts — and the one that pumps blood through their body stops every time they swim.
Octopuses have three hearts: two branchial (gill) hearts and one systemic heart. Most octopuses crawl rather than swim long distances (consequence of the stopping heart).
the largest of the three and the one closest in job to our own heart, driving oxygen-rich blood out into the arms.
two branchial hearts that pump blood through the gills, and one systemic heart that circulates oxygenated blood throughout the body.
the three hearts
many bottom-dwelling octopuses tend to crawl along the seafloor instead of swimming for long stretches
extremely exhausting
HEARTS
Two hearts push blood through the gills to pick up oxygen
Octopuses have three hearts: two branchial (gill) hearts and one systemic heart. Octopus blood uses hemocyanin (copper-based) instead of hemoglobin (iron-based), turning it blue when oxygenated.
Each hemocyanin monomer holds a pair of copper(I) cations in place via interactions with the imidazole rings of six histidine residues.
Octopuses and horseshoe crabs have blue blood because the protein transporting oxygen in their blood, hemocyanin, contains copper, instead of iron
The copper in hemocyanin makes their blood run blue.
the largest of the three and the one closest in job to our own heart, driving oxygen-rich blood out into the arms.
two branchial hearts that pump blood through the gills, and one systemic heart that circulates oxygenated blood throughout the body.
the three hearts
OCTOPUS
But when an octopus fires its jet to escape a predator
The systemic heart stops beating when the octopus uses jet propulsion.
When an octopus uses jet propulsion to swim — typically to escape a predator — its systemic heart actually stops beating. The muscular contractions required for jet-propelled swimming physically compress the heart, preventing it from pumping.
that systemic heart stops beating every time the octopus swims! When the mantle contracts hard to fire that jet, it pinches those drainage channels (called venous sinuses) shut from the outside.
COPPER
it uses copper
Octopus blood uses hemocyanin (copper-based) instead of hemoglobin (iron-based), turning it blue when oxygenated.
Each hemocyanin monomer holds a pair of copper(I) cations in place via interactions with the imidazole rings of six histidine residues.
Octopuses and horseshoe crabs have blue blood because the protein transporting oxygen in their blood, hemocyanin, contains copper, instead of iron
The copper in hemocyanin makes their blood run blue.
RATHER
So most octopuses crawl along the seafloor rather than swim
Most octopuses crawl rather than swim long distances (consequence of the stopping heart).
many bottom-dwelling octopuses tend to crawl along the seafloor instead of swimming for long stretches
extremely exhausting
THREE
Put your hand on your chest and count your heartbeats. You have one. They have three — and the hardest-working one stops when they run.
Put your hand on your chest and count your heartbeats. You have one. They have three — and the hardest-working one stops when they run.
“"Only 25% as effective as hemoglobin"”
— cited by ScienceABC but not independently corroborated in this fact-check. Exact efficiency ratio not spoken in the script.
“Antarctic hemocyanin cold-adaptation”
— verified (Scientific American 2013), but tangential. Not in scope for these beats.
“"Blue blood even when deoxygenated" nuance”
— technically hemocyanin is colorless/clear when deoxygenated, blue only when oxygenated. The script says "uses copper, which turns it blue" — accurate (standard shorthand used by Smithsonian, Scientific American, NHM) but taken to mean the oxygenated state. Not misleading; no correction needed.
Publishing what we refused to claim is the strongest evidence the rest was checked.