An octopus is a mollusk that has eight limbs and is a member of the Octopoda order.
Octopus is a common name used for about 300 described species.
The Octopoda order was coined by English biologist William Elford Leach in 1818.
There are two suborders of the Octopoda order, and they are the Incirrina and Cirrina.
Octopuses are carnivores that eat meat. Common prey includes fish, crabs, crayfish, shrimp and other mollusks.
Octopuses can rapidly alter their soft bodies and squeeze into small gaps between rocks and coral.
An octopus has a two part beak for its mouth.
Almost all octopus species have a very short lifespan, and some species only live for about six months.
The size of an octopus greatly varies by species. They can be as short as an inch or as long as 20+ feet.
A threatened octopus can eject a black inky fluid from their bodies, reducing visibility and confusing a predator or threat.
A common myth is an octopus's limb is called a tentacle. From a scientific point of view, they are arms.
An octopus can grow a new limb if one is lost.
An octopus has three hearts. One heart is used to pump blood between its organs. The other two are used to pump blood through its gills.
The giant Pacific octopus (Enteroctopus dofleini) is the largest living species of octopus. Their average adult weight is 33 pounds. The largest recorded size of a giant Pacific octopus was 156 pounds.
The star-sucker pygmy octopus (Octopus wolfi) is the smallest living species of octopus. Their average adult weight is less than one gram. They have an average length of only one inch.
The mimic octopus (Thaumoctopus mimicus) is known for its ability to mimic other marine animals. They can mimic other dangerous marine animals, like eels, lionfish and sea snakes.
The seven-arm octopus (Haliphron atlanticus) has been observed having a complex relationship with jellyfish. They appear to work together in capturing prey and protection each other.
The greater blue-ringed octopus (Hapalochlaena lunulata) has a very strong venom that can be fatal to humans.
The common octopus (Octopus vulgaris) can be found in virtually every ocean around the world.
The veined octopus (Amphioctopus marginatus) has been recorded using tools. They will gather up seashells and coconut shells and build themselves a shelter.
Octopuses appear to be very intelligent and most likely the smartest invertebrate. Experiments have shown they can store both short and long-term memories.