Why Octopuses Are the Weirdest Animals on Earth

Why Octopuses Are the Weirdest Animals on Earth

Octopuses have three hearts, blue blood, nine brains, and can edit their own RNA. They're so different from every other animal on Earth that scientists have called them "the closest thing to aliens we'll find on this planet."

The Weird Biology

Three hearts:

• Two branchial hearts pump blood through the gills
• One systemic heart pumps blood to the body
• The systemic heart stops beating when swimming (why they prefer crawling)

Blue blood:

• Uses hemocyanin (copper-based) instead of hemoglobin (iron-based)
• Better at transporting oxygen in cold, low-oxygen deep water
• Less efficient than hemoglobin in warm, oxygen-rich water

Nine brains:

• One central brain (doughnut-shaped around the esophagus)
• Eight mini-brains (one in each arm, containing 2/3 of all neurons)
• Each arm can act independently — touch, taste, and move without central direction
• Arms can even continue reacting to stimuli after being severed

RNA editing:

• Most animals: DNA → RNA → protein (fixed process)
• Octopuses: Can edit their RNA after transcription
• Allows rapid adaptation without changing DNA
• Tradeoff: Slower evolution (can't edit DNA as efficiently)
• Only a handful of species do this — and octopuses do it more than any other

Intelligence

• 500 million neurons (similar to a dog)
• Solve mazes, open jars, use tools, recognize individual humans
• Inky the octopus: Escaped from New Zealand aquarium through a drain pipe
• Otto the octopus: Threw rocks at aquarium lights to short-circuit them
• Can unscrew jar lids from the inside (escape artists)
• Play behavior observed (similar to mammals)

Camouflage

• Chromatophores: Pigment cells that expand/contract in milliseconds
• Can change color, pattern, and texture in 0.3 seconds
• Match surroundings perfectly (including texture — bumpy, smooth, spiky)
• Can mimic other animals (flatfish, lionfish, sea snakes)
• Use camouflage for hunting AND communication

Distributed Intelligence

• 2/3 of neurons are in the arms, not the central brain
• Arms make decisions independently ("submarine command" model)
• Central brain sends general instructions, arms figure out execution
• This is unlike any other nervous system on Earth
• Convergent evolution with vertebrate intelligence (evolved separately, similar result)

Short Lifespan Paradox

• Most species live only 1-3 years
• This is bizarre: Why be so intelligent if you die so quickly?
• Theory: Intelligence needed for survival (no shell, no school, solitary)
• Another theory: Short lifespan prevents them from accumulating cultural knowledge that could make them dangerous (to us)
• Learning is rapid but not passed to offspring (no parental care)
• Each octopus starts from scratch

The Alien Comparison

• 600 million years of separate evolution from humans
• Their nervous system evolved independently from all other intelligent animals
• No other invertebrate comes close to their intelligence
• If octopuses had longer lifespans and social behavior, they might rival human civilization
• Some scientists argue they should be classified as "honorary vertebrates" for animal welfare purposes

Fun Facts

• 36,000 taste buds on each arm (humans have 10,000 total)
• Can squeeze through any gap larger than their beak (the only hard part)
• Blood is blue because of copper-based hemocyanin
• Can regenerate lost arms (takes 2-3 months)
• Die after reproducing (males: months; females: guard eggs for months, then die)
• Have been observed using coconut shells as armor (tool use)

The Takeaway

Octopuses are the product of 600 million years of independent evolution — and they've arrived at intelligence, problem-solving, and tool use through a completely different path than humans. They're not "smart like us" — they're smart in a way nothing else on Earth is smart. If we ever do find aliens, there's a good chance they'll be more like octopuses than like us.