Broadclub Cuttlefish in Mauritius — Sepia pharaonis

The broadclub cuttlefish (Sepia pharaonis), known locally as Seiche, is one of the largest and most striking cuttlefish species in the Indo-Pacific. Reaching up to 50 cm in mantle length and weighing as much as 5 kg, this impressive cephalopod is a regular sight for divers and snorkellers exploring the warm, clear waters surrounding the island of Mauritius. Its common name refers to the broad, club-shaped tentacle tips it uses to snatch prey with lightning speed.

Appearance and Behaviour

Like all cuttlefish, Sepia pharaonis is a biological marvel of camouflage and communication. Its skin contains millions of chromatophores, iridophores, and papillae that allow it to mimic the colour, texture, and pattern of virtually any substrate within seconds. Observers frequently watch in disbelief as a cuttlefish hovering over sand transforms into a near-perfect replica of a coral head or rocky rubble.

Beyond camouflage, broadclub cuttlefish use their colour-changing ability for social signalling. Males display vivid, rippling zebra-stripe patterns — known as passing cloud displays — to court females or warn rival males. When threatened, they flash dramatic warning patterns and can release a cloud of dark ink as a decoy before jetting away. Despite their otherworldly appearance, cuttlefish are highly intelligent, with relatively large brains for invertebrates and demonstrated problem-solving capabilities.

Diet and Hunting

Broadclub cuttlefish are active and efficient predators. They feed primarily on small fish, shrimp, crabs, and other crustaceans. Hunting typically involves a slow, hypnotic approach — the cuttlefish undulating its lateral fins to hover almost motionlessly — before unleashing two long feeding tentacles in a strike too fast for the human eye to follow. Juveniles begin hunting small shrimp and larval fish almost immediately after hatching, displaying instinctive precision from birth.

Habitat in Mauritius

In Mauritius, broadclub cuttlefish are commonly found in a variety of habitats ranging from shallow seagrass beds and sandy lagoons to deeper coral reef slopes and rocky outcrops. They favour areas where coral rubble or mixed substrate provides good ambush opportunities. Juveniles are often spotted sheltering among branching corals, while adults tend to roam the reef edge and sandy channels. The warm, sheltered lagoons on the west and north coasts of Mauritius are particularly productive areas for cuttlefish sightings.

Reproduction

Breeding aggregations of broadclub cuttlefish are a spectacular natural event. Males compete intensely for females, with larger males using their display patterns and body posturing to assert dominance. Smaller males sometimes use a cunning strategy — mimicking female colouration and body shape to slip past dominant males and mate undetected. Females lay clusters of dark, grape-like eggs anchored to coral branches or rocky crevices. The eggs develop over several weeks before miniature, fully formed cuttlefish hatch out — already equipped with their parents' remarkable camouflage abilities.

Ecological Role

As mid-level predators, broadclub cuttlefish play an important role in maintaining balance within reef ecosystems. They help regulate populations of small fish and crustaceans, and in turn serve as prey for larger fish such as groupers, barracuda, and reef sharks. Their discarded cuttlebones — the internal calcified structure used for buoyancy control — are commonly found washed ashore on Mauritian beaches and provide calcium-rich supplements used by birds worldwide.

Diving with Broadclub Cuttlefish

Mauritius offers excellent opportunities to observe Sepia pharaonis up close. These animals are relatively bold, often allowing divers to approach slowly and observe their behaviour at close range. The key is calm, unhurried movement — sudden gestures or bubbles directed at the animal will cause it to ink and flee. Night dives are particularly rewarding, as cuttlefish are often more active after dark and their colour-change displays are especially vivid under torch light. Experienced dive guides across the island know the favoured resting spots and hunting grounds of local individuals, making a guided dive the best way to maximise your chances of a memorable encounter.