Head to head
Cuttlefish vs Common Octopus
Cuttlefish and octopuses are close cousins — both cephalopods, both soft-bodied, both among the most intelligent invertebrates and the best camouflage artists in the sea. But they are built on different plans and make a living in different ways.
| Cuttlefish | Common Octopus | |
|---|---|---|
| Group | Cephalopod, order Sepiida | Cephalopod, order Octopoda |
| Internal skeleton | A gas-filled cuttlebone for buoyancy | None — only a small cartilage brain case |
| Arms and tentacles | 8 arms plus 2 long retractable feeding tentacles | 8 arms, no tentacles |
| Body shape | Broad, flattened, fin-fringed; hovers in open water | Bag-like, no fins; crawls and dens on the bottom |
| Camouflage | Fastest, most complex dynamic skin displays known | Excellent — colour, texture, and shape mimicry |
| Hunting | Ambush; shoots feeding tentacles in ~30 ms | Actively forages; probes crevices with arms |
| Lifespan | 1–2 years | 1–2 years |
| Vision | W-shaped pupil; likely colour-blind | Slit or round pupil; likely colour-blind |
| Conservation status | Least Concern | Least Concern |
Cuttlefish vs Octopus: common questions
Are cuttlefish and octopuses the same thing?
No, but they are close relatives. Both belong to the cephalopods, along with squid and nautilus. The clearest differences: a cuttlefish has an internal shell (the cuttlebone) and ten appendages — eight arms plus two long feeding tentacles — while an octopus has no shell at all and just eight arms.
Which is smarter, a cuttlefish or an octopus?
Both are among the most intelligent invertebrates and it is hard to rank them. Octopuses are famous for tool use, opening jars, and escaping enclosures. Cuttlefish have shown self-control in "marshmallow test" style experiments and remember the what, where, and when of past meals. They are smart in somewhat different directions.
Which one changes colour better?
The cuttlefish, by most measures. It has the fastest and most elaborate skin signalling of any animal, able to run moving patterns across its body and show different displays on each flank at once. Octopuses camouflage superbly too, and some, like the mimic octopus, impersonate other species — but the cuttlefish is the display specialist.