THE ANIMAL FILES

Common cuttlefish

Sepia officinalis

Eight holding arms, two reaching tentacles.

The common cuttlefish combines an internal shell with a highly changeable exterior. Its arms hold prey, specialized tentacles reach for it, and skin can change pattern and texture. Each part answers a different question about how a soft-bodied hunter feeds, hides and escapes.[1]

Follow the evidence ↓
Common cuttlefish
Image: Diego Delso · Commons · CC BY-SA 4.0
Support
An internal cuttlebone[1]
Appendages
Eight arms and two feeding tentacles[1]
Disguise
Changing skin pattern and texture[1]

Different tools around one mouth

Eight arms surrounding the mouth manipulate and hold prey, while two specialized feeding tentacles help capture it. The beak and radula then process food. Counting appendages is useful, but their functions add more information: reaching, holding and breaking food apart are separate tasks rather than interchangeable uses of one generic tentacle.[1]

A surface that changes shape

Pigment-bearing and light-reflecting structures contribute to camouflage. Muscles can also change skin texture, adding a three-dimensional component to the disguise.[1]

Hide first, escape next

Camouflage can keep a predator from locating a cuttlefish in the first place. If discovered, the animal can use its siphon to jet away and may release ink. These defenses work at different stages of an encounter. A concealed animal and a rapidly escaping one can be using parts of the same defensive repertoire.[1]

A COMMON MIX-UP

Does having a shell always mean wearing one outside?

No. The cuttlebone is internal. The visible outline alone does not reveal every supporting structure in a mollusc.[1]

TRY A LITTLE REASONING

Why might color alone be unreliable for recognizing this cuttlefish?

Reveal the explanation

It can change patterns and texture. Arms, tentacles and the general body plan provide additional clues that are less dependent on its current display.[1]

Sources & editorial notes

Adapted and translated from the cited Wikipedia revisions, with source-linked reasoning. Image credit and licence are listed separately above.

Adapted and translated from Wikipedia contributors; exact revisions are linked below. CC BY-SA 4.0

  1. Wikipedia contributors — Sepia officinalis (adapted and translated; exact revision)
  2. NCBI Taxonomy — Sepia officinalis (identity and game lineage)

Last fact check:

One discovery leads to another

Giant squidTwo long tentacles catch; eight arms bring the catch to a beak.Architeuthis dux ↗Vampire squidThe “vampire” collects sinking scraps instead of drinking blood.Vampyroteuthis infernalis ↗Greater blue-ringed octopusBright blue can be revealed by opening folds in the skin.Hapalochlaena lunulata ↗