Found worldwide in the shallow waters of tropical, subtropical, and temperate areas, the common octopus is a fascinating creature.
Octopuses are mollusks! Photo by tane-mahuta / iStock.com.
Similar to a squid, the common octopus is classified as a mollusk, which is a soft-bodied invertebrate with a shell. It has no skeletal structure but does possess a skull, which protects its brain.
At 60-90 cm (24-36 in.) long, it has eight long limbs protruding from a globe-shaped head (or mantle). It also has a sharp beak and a toothed tongue called a radula.
Arms or Legs?
While it was commonly believed that the octopus’s appendages were all arms, recent studies by marine experts have shown that two of the limbs act more as legs, allowing it to walk across the sea floor and push off when swimming.
Octopuses have two rows of suckers on their tentacles that can sense taste.
The octopus also has the useful ability to regenerate a tentacle if it loses one.
Ability to Change Color
When confronted with a predator–like a dolphin, shark, or eel–the octopus may change the color, pattern, and texture of its skin to blend in with its surroundings. Pigment cells in the skin contract to allow for seamless camouflage capabilities.
Common octopus in the Aegean Sea, Greece. Photo by AlexeyMasliy / iStock.com.
In addition to camouflage, an octopus may change color to scare away potential predators. The areas around their eyes, suckers, arms, and web may darken so the octopus appears more threatening.
Octopuses also change color to reflect their mood. While common octopuses are normally brown, they may turn white, which shows fear, or red, which demonstrates anger.
Octopus Ink
In addition to changing color, octopuses also use ink and flight as a defense tactic.
When threatened, an octopus may release a cloud of purple-black ink. Then it propels itself by funneling water from its gills at the top of its mantle through its siphon, located at the bottom of the mantle.
It can reach speeds as high as 40 km/h (25 mph), but cannot maintain this speed for long.
What Common Octopuses Eat
A common octopus hunting in the Aegean Sea. Photo by AlexeyMasliy / iStock.com.
The common octopus uses its radula to pry open and drill into the shells of prey, like crabs and clams.
Once it breaks into the shells, it may also inject a paralyzing poison into its prey.
Octopus Dens
Octopuses are solitary animals who make their homes in rocks and coral or dig burrows. They scatter rocks and shells (or midden) around their dens to hide them.
They leave the dens only to eat or reproduce.
Common octopus in the Aegean Sea, Greece. Photo by AlexeyMasliy / iStock.com.
Common Octopus Reproduction
In early spring, octopuses move closer to the shore to mate.
Two months after mating, the female releases 100,000-500,000 eggs. She spends her time cleaning the eggs, providing oxygen by squirting water, and fending off predators.
Soon after the eggs hatch, both the male and female octopuses die. They only live 12-18 months.
Meanwhile, the hatchlings are carried by the currents, and they feed on plankton for 45-60 days. Only one or two of the hatchlings will survive to adulthood.
Conservation Status
Currently, common octopuses are not considered endangered or threatened by the IUCN Red List.
However, octopus is a common food in Asian and Mediterranean cuisines. People catch octopuses by trawling (fishing with a large net) and by luring them into “octopus pots,” which are plastic traps that octopuses confuse as suitable dens.
If trawling coincides with their breeding season or if overfishing occurs, octopus populations could be in danger.
Common Octopus Range
Common octopuses are found worldwide in the shallow waters of tropical, subtropical, and temperate areas.
More Octopus Resources
- The Cephalopod Page’s Octopus vulgaris Article by Dr. James B. Wood
- Marine Invertebrates of Bermuda’s Common Octopus Article by Melissa L. Pierce
- The Big Zoo’s Common Octopus Page
- “Octopuses have two legs and six arms,”Telegraph, August 12, 2008
Quick Fact Sheet
Common Name(s): Common Octopus
Scientific Name: Octopus vulgaris
Animal Type: invertebrate
Size: 60-90 cm (24-36 in.) long
Weight: 3-10 kg (6.6-22 lb.)
Lifespan: 12-18 months
Conservation Status: Least Concern
About the Author
Abi Cushman is a contributing editor of Animal Fact Guide and My House Rabbit. When she's not writing about weird animal facts, Abi writes and illustrates funny books for kids. Her picture books, Soaked! and Animals Go Vroom!, are available now from Viking Children's Books.
To learn more and to download free activity sheets, visit www.abicushman.com. Follow her on Instagram at @Abi.Cushman.
