Octopuses are among the ocean's strangest and smartest residents, capable of problem-solving, dramatic camouflage, and squeezing through gaps barely wider than their eyeballs. With over 300 known species living everywhere from coral reefs to the deep sea, there's always something new to learn about them.
Here are verified facts about octopus biology, intelligence, and behavior, plus answers to the most common questions people ask about these eight-armed escape artists.
Octopuses are considered the most intelligent invertebrates, capable of learning, problem-solving, and using tools; researchers debate exactly how their intelligence compares to primates, since it evolved along a completely different path.
Octopuses have three hearts: two pump blood to the gills, while the third circulates it to the rest of the body.
Octopus blood is blue rather than red, because it uses a copper-based protein called hemocyanin instead of iron-based hemoglobin to carry oxygen.
Octopuses can change both the color and texture of their skin in a fraction of a second to blend in with rocks, coral, or plants.
Octopuses have eight arms, not tentacles. Arms are lined with suckers along their entire length, while true tentacles (found on squid and cuttlefish) have suckers only near the tip.
Each of an octopus's arms contains its own cluster of neurons, letting the arms taste, sense, and react semi-independently of the brain.
Most octopuses are mildly venomous, but only the blue-ringed octopus is dangerous to humans; its venom can cause paralysis and, in rare cases, death.
If an octopus loses an arm, it can regenerate it over the course of a few months thanks to strong regenerative abilities.
Octopuses are largely solitary and mostly interact with others only to mate.
Octopuses live in every ocean on Earth, from shallow tide pools to the deep sea, and there are roughly 300 known species.
Octopuses have no internal or external skeleton, which lets them squeeze through any gap larger than their hard beak.
Most octopus species have short lives, typically living six months to five years depending on species; the giant Pacific octopus, one of the longest-lived, survives about 3 to 5 years.
Male octopuses transfer sperm to females using a specialized arm called a hectocotylus.
A female octopus lays thousands of eggs and guards them constantly, often without eating, until they hatch; some deep-sea octopuses have been observed brooding eggs for over four years.
Octopuses are known escape artists in captivity, able to open latched lids and squeeze through very small openings to get out of tanks.
The giant Pacific octopus is the largest octopus species, with arm spans that can reach around 16 feet (about 5 meters).
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