Insects & Invertebrates comparison

Octopus vs Cuttlefish: Key Differences Explained

The short answer

Both are exceptional camouflage artists, but they are built differently. An octopus has eight arms, no internal skeleton at all, and squeezes through gaps on the seafloor. A cuttlefish has eight arms plus two feeding tentacles and a thick chambered cuttlebone that lets it hover in mid-water with almost no effort. The octopus manipulates and explores; the cuttlefish hovers and signals.

The main difference

An octopus is a boneless eight-armed manipulator that squeezes and explores; a cuttlefish is a ten-appendaged hoverer with a buoyancy-regulating cuttlebone.

They are the two most accomplished colour-changers in the sea, and comparing them shows two different bodies putting the same skin technology to different uses.

At a glance

Comparison of Octopus and Cuttlefish across 6 dimensions, with an interpretation of each difference.
What differs	Octopus	Cuttlefish	What it means
Appendages	Eight arms and no feeding tentacles	Eight arms plus two extensible feeding tentacles	Appendage count separates them immediately on any clear view.
Internal support	None beyond the beak	A thick chambered cuttlebone regulating buoyancy	One can pour itself through a gap; the other can hang motionless in mid-water.
Typical movement	Crawls over the bottom on its arms, jetting when it needs speed	Hovers and glides using the mantle fin, jetting when startled	Crawling versus hovering is the clearest behavioural difference at a distance.
Camouflage repertoire	Colour, pattern and raised skin papillae producing three-dimensional texture	Colour, pattern, texture and dynamic moving displays used in hunting and signalling	Both are outstanding; the cuttlefish uses moving patterns more heavily in social signalling.
Habitat	Reefs, rocky bottoms and soft sediment, typically with a den	Coastal shallows, seagrass and reef, hovering just above the bottom	Both are bottom-associated, but one lives in structure and the other above it.
Use of arms	Manipulation, exploration, prying open shells and carrying objects	Chiefly holding prey after the tentacle strike	Octopus arms are general-purpose tools in a way cuttlefish arms are not.

Appendages: OctopusEight arms and no feeding tentacles
CuttlefishEight arms plus two extensible feeding tentacles
Appendage count separates them immediately on any clear view.
Internal support: OctopusNone beyond the beak
CuttlefishA thick chambered cuttlebone regulating buoyancy
One can pour itself through a gap; the other can hang motionless in mid-water.
Typical movement: OctopusCrawls over the bottom on its arms, jetting when it needs speed
CuttlefishHovers and glides using the mantle fin, jetting when startled
Crawling versus hovering is the clearest behavioural difference at a distance.
Camouflage repertoire: OctopusColour, pattern and raised skin papillae producing three-dimensional texture
CuttlefishColour, pattern, texture and dynamic moving displays used in hunting and signalling
Both are outstanding; the cuttlefish uses moving patterns more heavily in social signalling.
Habitat: OctopusReefs, rocky bottoms and soft sediment, typically with a den
CuttlefishCoastal shallows, seagrass and reef, hovering just above the bottom
Both are bottom-associated, but one lives in structure and the other above it.
Use of arms: OctopusManipulation, exploration, prying open shells and carrying objects
CuttlefishChiefly holding prey after the tentacle strike
Octopus arms are general-purpose tools in a way cuttlefish arms are not.

How they are related

Both are coleoid cephalopods, but octopuses form Octopoda while cuttlefish are decapodiforms in Sepiida alongside squid. They share ink defence, jet propulsion, a hard beak, chromatophore skin and large complex nervous systems, and diverged in body plan around the retention or loss of the ancestral shell.

Telling them apart

Count the appendages and look at how the animal moves. Eight arms and a boneless body crawling over rock is an octopus. Ten appendages, a broad flattened body and a fin rippling along the mantle while the animal hovers is a cuttlefish. The cuttlefish's W-shaped pupil confirms it where the eye is visible.

Eight arms, boneless, crawling over rock, disappearing into a crevice: octopus. Ten appendages, broad flattened body, fin rippling along the mantle while hovering above sand: cuttlefish. Both are extraordinary camouflage artists, and neither is a fish.

Habitat and distribution

Octopuses occupy reefs, rocky bottoms and soft sediment worldwide, generally maintaining a den to which they return. Cuttlefish occupy coastal and shelf waters of Europe, Africa, Asia and Australia over sand, seagrass and reef, and are absent from the Americas. Both are bottom-associated but use that habitat differently.

Diet and ecological role

Octopuses take crabs, bivalves, snails and fish, using arms and suckers to explore crevices, extract prey and prise open shells, and some drill through shells to inject a paralysing secretion. Cuttlefish strike at crustaceans and fish with the two extensible tentacles, often after stalking the prey with a rippling display of moving colour bands.

Behaviour

Octopuses are notable for manipulative problem-solving, den maintenance and using objects as shelter, and most are solitary. Cuttlefish rely heavily on visual signalling in courtship and rivalry, with males of some species producing courtship patterns on the side facing a female and rival-deterring or female-mimicking patterns on the other. Both are mostly short-lived and reproduce once.

Senses and adaptations

Both control skin colour and texture through chromatophores under direct nervous control, and both raise papillae to create three-dimensional texture matching their surroundings. Remarkably, both appear to be colourblind by conventional measures, and one leading hypothesis is that light-sensitive proteins in the skin itself contribute to how they assess and match their background.

More on this topic: Animal senses and adaptations.

People and these animals

Both are fished commercially and both are central to research on camouflage, vision and invertebrate cognition. Cuttlebone has long been sold as a calcium supplement for caged birds. Cephalopods are increasingly included in animal welfare legislation on the grounds of neural complexity, and octopus farming in particular has attracted substantial ethical debate.

What they have in common

Both are coleoid cephalopods with a hard beak, ink defence and jet propulsion.
Both change colour and three-dimensional skin texture within a fraction of a second.
Both are active predators with large complex nervous systems and image-forming eyes.
Both are typically short-lived and reproduce once before dying.

Key differences

An octopus has eight arms; a cuttlefish has eight arms plus two feeding tentacles.
The cuttlebone regulates buoyancy, while an octopus has no internal support at all.
Octopuses crawl and squeeze through gaps; cuttlefish hover using a full-length mantle fin.
Octopus arms are general-purpose manipulators, whereas cuttlefish arms mainly hold prey.
Cuttlefish are absent from the Americas, while octopuses occur worldwide.

Where people go wrong

Assuming any soft-bodied cephalopod that changes colour is an octopus.
Expecting a cuttlefish to squeeze through gaps, which the cuttlebone prevents.
Treating the two as equally distributed, when cuttlefish are absent from the Americas.

Frequently asked questions

How do I tell an octopus from a cuttlefish?

Count the appendages and watch the movement. An octopus has eight arms and nothing else, and it crawls over the bottom using them, squeezing into crevices because it has no skeleton. A cuttlefish has eight arms plus two longer feeding tentacles, a broad flattened body, and a fin rippling along the whole mantle as it hovers just above the seafloor.

Which is better at camouflage?

Both are outstanding, and ranking them is not really meaningful. Both change colour, pattern and three-dimensional skin texture within a fraction of a second. Cuttlefish make heavier use of dynamic moving displays, both to mesmerise prey and to signal to other cuttlefish, while octopuses excel at matching complex reef backgrounds and can mimic the appearance of other animals and objects.

Can a cuttlefish squeeze through gaps like an octopus?

No. The cuttlebone is a rigid internal structure running most of the length of the mantle, so a cuttlefish cannot deform its body the way an octopus can. An octopus has no skeleton beyond its beak, which is why anything the beak fits through the rest of the animal can generally follow. The cuttlebone buys buoyancy control at the cost of flexibility.

Are they both colourblind?

By conventional measures, yes — both appear to have a single visual pigment, which should make colour discrimination impossible in the usual sense. This sits oddly with their precise colour matching. Proposed explanations include extracting colour information from chromatic blur produced by unusual pupil shapes, and light-sensitive proteins in the skin itself contributing to background assessment. The question is not fully resolved.

Read the full profiles

Sources and methodology

How this comparison is built: FaunaHub comparisons are assembled from the sourced animal profiles behind them rather than written as standalone claims. Figures such as size, mass, and lifespan are typical ranges that vary by subspecies, population, region, sex, age, and — where relevant — whether an animal lives in the wild or under human care, so they are presented as ranges rather than fixed values. Where a common name covers a group rather than a single species, the page says so instead of implying a species-to-species match. Conservation status changes over time and should be confirmed against the current IUCN Red List. Dimensions that could not be supported from the underlying profiles are omitted rather than filled in.

What this page does not do: it does not rank the two animals, predict the outcome of a confrontation, or present either one as stronger, smarter, or better. It is not veterinary, medical, first-aid, handling, capture, hunting, or pest-control guidance. For an animal in your care, or any situation involving injury, contact a qualified veterinarian, your local wildlife authority, or emergency services.

Sources and further reading

Authoritative references used for general educational context. External links open in a new tab. These sources do not endorse FaunaHub.

UniversityAnimal Diversity Web — Octopus vulgaris (common octopus) — University of Michigan species account
ReferenceBritannica — Octopus — order Octopoda — Editor-reviewed encyclopedia entry
Wildlife referenceIUCN Red List of Threatened Species — Authoritative source for current conservation status
ReferenceWoRMS — World Register of Marine Species — Authoritative register of marine species names
ReferenceBritannica — Cuttlefish — Editor-reviewed encyclopedia entry
ReferenceSmithsonian Ocean — National Museum of Natural History — Smithsonian Institution educational ocean-science resource
GovernmentNOAA Fisheries — Marine Life — U.S. government science agency for marine species and habitats

Last updated: 2026-08-04