Invertebrates
Flamboyant Cuttlefish
Metasepia pfefferi · also called flamboyant cuttlefish, Pfeffer's flamboyant cuttlefish
The flamboyant cuttlefish is a small cuttlefish with a big personality. It walks rather than swims, picking its way across silty flats on arm-tips and leg-like flaps, and when something bothers it, it lights up — pulsing hypnotic waves of yellow, red, and purple across its skin as a warning that its flesh is poison.
Overview
Flamboyant cuttlefish live on sand and mud bottoms in the shallow tropical Indo-Pacific, from northern Australia and Indonesia through the Philippines and Papua New Guinea. They are tiny — a mantle just 6–8 cm — with a broad, flattened, flap-covered body, and they hunt small fish and crustaceans by creeping close and firing out two long feeding tentacles.
Walking, not swimming
Its cuttlebone is unusually small, so it is barely buoyant and swimming is costly. Instead it “walks” across the seabed on the tips of its arms and two broad flap-arms that work like legs, fins rippling for balance — a gait almost unique among cuttlefish. It can still jet away in a burst if it must.
The display
At rest and hunting, it wears drab sandy brown for camouflage. Disturbed, it flushes vivid waves of yellow, maroon, red, and white, raises its arms, and makes itself maximally conspicuous — an aposematic warning, not camouflage.
Toxic flesh
The flamboyant cuttlefish is the only cuttlefish known to have poisonous muscle tissue, reportedly with a toxin comparable to a blue-ringed octopus’s. Crucially, it is a poison in the meat — dangerous if eaten — not a venom delivered by a bite. The bright colours are the warning; the correct response is simply not to touch it.
Status
The flamboyant cuttlefish has not been assessed for conservation. It is patchily distributed, wild-caught for the aquarium trade despite being hard to keep and short-lived, and best left in the sea.
Flamboyant Cuttlefish: common questions
Why does the flamboyant cuttlefish put on such a colourful display?
It is a warning, not camouflage. Most cuttlefish use their colour-change ability to blend into the background, but when a flamboyant cuttlefish is disturbed it does the opposite — it flushes waves of vivid yellow, maroon, red, and white across its skin, holds up its arms, and makes itself as conspicuous as possible. The purpose is aposematism — advertising to a would-be predator that the animal is toxic and not worth eating. When it is not threatened and is simply hunting, it usually shows a much duller brown, drab pattern that matches the sandy bottom, so it can approach prey unseen. The famous "flamboyant" display is a defence reserved for when hiding has failed.
Is the flamboyant cuttlefish really poisonous?
Its muscle tissue has been found to contain a potent toxin, making it, as far as is known, the only cuttlefish with poisonous flesh. Some reports describe the toxin as comparable in danger to that of the blue-ringed octopus. The important qualifier is the delivery route — this is a poison in the meat, harmful if the animal is eaten, not a venom injected by a bite. There is no evidence a flamboyant cuttlefish poses a bite hazard to a diver, and its small beak could not do much damage anyway. The sensible response is simply not to handle it (both for your safety and the animal's) and certainly not to eat it. The bright colours are the animal telling you exactly this.
Why does it walk on the bottom instead of swimming?
The flamboyant cuttlefish has an unusually small cuttlebone (the internal buoyancy shell) relative to its body, so it is not very buoyant and swimming costs it a lot of effort. Instead it has adopted a bottom-walking gait — it moves across the sand on the tips of its arms and on two broad, flap-like arms that act almost like legs, with its fins rippling for balance and steering. This lets it creep slowly and precisely up to prey and hunt on silty flats where hovering in the current would be inefficient. It can still jet-swim in a burst if it has to escape, but walking is its default.
Can you keep one in an aquarium?
They are sometimes sold for marine aquariums and are prized for their colour and behaviour, but they are considered a poor choice. They are wild-caught (they are difficult to breed), they have a very short natural lifespan of little more than a year so a purchased adult may already be near the end of its life, they need live food, and they are delicate. Collecting them also removes breeding adults from patchy wild populations. Responsible aquarium and conservation guidance is generally to leave the flamboyant cuttlefish in the sea and enjoy it through photos and video.