The oldest known octopus fossil belongs to an animal that lived 296 million years ago.
Octopuses have three hearts.
The plural of "octopus" is "octopuses".
Octopuses have blue blood due to a copper-based protein called hemocyanin. 
The smallest octopus is the wolfi, which is smaller than 2.5 cm long.
The giant Pacific octopus grows bigger and lives longer than any other octopus species. 
The largest recorded octopus was 30 feet across and weighed more than 600 pounds.
When they hatch, baby octopuses are called larvae. 
Female octopuses usually lay fromm 200,000 to 400,000 eggs.
Among shallow water octopus species, we observe short life spans, ranging from six months to as long as five years.  
Octopuses can lose arms and regrow them.
Octopuses have been observed using tools.
An octopus can change the color of its entire body in just three-tenths of a second.
A common octopus has about 240 suckers on each limb; a particularly large sucker can hold up to 35 lbs.
In 2016, Inky the octopus at the National Aquarium of New Zealand escaped its tank into a drainpipe that led directly to the sea.
There are about 300 species of octopus.
All octopuses have venom. 
Octopuses have decentralized brains. 
Deep-sea octopuses can't produce ink. 
Octopuses can breathe and see through their skin.
Octopuses possess short and long-term memory; they can observe and remember people and animals. 
Octopuses can see 360 degrees around themselves: they don't have a blindspot.
There are two octopus species with lethal tetrodotoxin (TTX): Blue-Ringed Octopus and Mototi Octopus.
Octopuses are about 90% muscle.
Because they lack bones, octopuses can fit through very small spaces.
Octopuses are found in every ocean of the world.
Octopuses have about half a billion neurons, similar to dogs.
Octopuses swim by jet propulsion. 
The balloon dumbo octopus has bioluminescent organs.
Octopuses can morph their skin into three-dimensional shapes to enhance camouflage.
The species Octopus cyanea change their appearance more than 150 times per hour on Pacific coral reefs.
The mimic octopus mimic the shape, coloration, and swimming of other fish.
To a human observer, octopuses can sometimes look like stones, algae, seagrasses, and coral. 
The first cephalopod genome to be sequenced and annotated was of Octopus bimaculoides in 2015.
The genome size of octopuses is nearly the size of mouse and human genomes. 
Octopuses and other cephalopods edit their nervous system RNA at an astonishing rate, more than any other known organism.
Robotic engineering has benefited from imitating the soft, flexible, strong arms of octopuses.
Octopuses collect sea shells, bits of coral, and other found objects to place around the perimeter of their habitat.
The wolfi octopus was discovered in 1913.
Octopuses have strong eyesight and are suspected of being able to seeing color in a very different way than humans.