Octopus
Octopus vulgaris
Quick answer
The octopus is a soft-bodied marine invertebrate with eight arms, three hearts, and blue, copper-based blood, widely regarded as the most intelligent of all invertebrates. Octopuses can change color and texture in an instant to camouflage, squeeze through tiny gaps, and solve problems and use tools. Most species are short-lived, typically around 1 to 2 years.
Octopus facts at a glance
| Scientific name | Octopus vulgaris |
|---|---|
| Diet | Carnivore |
| Habitat | Oceans, from reefs to the deep sea |
| Lifespan | 1–2 years (most species) |
| Weight | 3–10 kg (7–22 lb) common octopus |
| Top speed | Up to 25 km/h (16 mph) in a jet burst |
| Conservation status | Least Concern (IUCN) |
| Kingdom | Animalia |
|---|---|
| Phylum | Mollusca |
| Class | Cephalopoda |
| Order | Octopoda |
Three hearts and blue blood
An octopus has three hearts: two pump blood through the gills and one circulates it to the body. Its blood is blue because it uses copper-based hemocyanin instead of iron-based hemoglobin to carry oxygen, which works well in cold, low-oxygen water. The main heart even stops beating when the octopus swims, which is why many prefer to crawl.
Masters of disguise
Octopuses can change the color, pattern, and even texture of their skin in milliseconds using millions of pigment-filled cells called chromatophores. This lets them vanish against rock, coral, or sand to ambush prey and hide from predators. Some species also mimic other animals or objects entirely.
Remarkable intelligence
Octopuses have large brains and, unusually, much of their nervous system is spread through their arms, so each arm can act semi-independently. They solve puzzles, open jars, use coconut shells and rocks as tools and shelter, and can recognize individual people, making them the most intelligent invertebrates known.
Bodies without bone
With no internal or external skeleton, an octopus can squeeze its entire body through any gap larger than its hard beak, the only rigid part. It moves by crawling on its arms or by jet propulsion, squirting water from a siphon, and can release a cloud of ink to escape danger.
Frequently asked questions about the Octopus
How many hearts does an octopus have?
An octopus has three hearts. Two pump blood through the gills, and one pumps it to the rest of the body. The main heart stops when the octopus swims, which is one reason they often prefer to crawl.
Why is octopus blood blue?
Octopus blood is blue because it uses a copper-based molecule called hemocyanin, rather than the iron-based hemoglobin in our red blood, to carry oxygen efficiently in cold seawater.
How do octopuses change color?
Octopuses change color using millions of tiny pigment cells called chromatophores in their skin, plus layers that reflect light, allowing near-instant camouflage in color, pattern, and texture.
Are octopuses intelligent?
Yes. Octopuses are the most intelligent invertebrates known. They solve puzzles, use tools, open jars, escape enclosures, and can recognize individual people, with much of their nervous system in their arms.
How long do octopuses live?
Most octopuses are short-lived, typically 1 to 2 years. They usually die soon after reproducing, with females guarding their eggs until they hatch and then passing away.
