Macro
Spanish Dancer
Hexabranchus sanguineus · Marine gastropod mollusk — family Hexabranchidae; one of the largest nudibranchs known
Most nudibranchs crawl; the Spanish dancer, disturbed, lets go of the reef and swims — mantle skirts flaring and rolling in the deep-red flamenco motion that named it. It ranks among the largest of all nudibranchs, a crimson animal that can reach forearm length, and it is almost strictly nocturnal, which makes it a signature night-dive find across the Indo-Pacific and Red Sea. By torchlight look for one plowing across open reef between sponge meals, often carrying passengers: emperor shrimp ride the mantle folds like deckhands. Its eggs are as recognizable as the animal, a rose-shaped ribbon of pink spirals fixed to hard bottom and chemically defended like the adult. Watch a voluntary swim from a respectful distance; forced performances exhaust an animal with nowhere to hide.
Where and when to see one
"Resident" means most dives at that destination encounter them; "seasonal" means reliably present in the listed months; anything else is a bonus, not a plan.
| Destination | Reliability | Months | Notes |
|---|---|---|---|
| Sharm El Sheikh & Ras MohammedEgypt | Occasional | Year-round | |
| North & South Malé AtollsMaldives | Occasional | Year-round | |
| Marsa Alam & the Deep SouthEgypt | Occasional | Year-round | |
| Lembeh StraitIndonesia | Occasional | Year-round | |
| Kona, HawaiʻiUnited States | Occasional | Year-round |
Best month, at a glance
Understanding them
Habitat: Coral reefs, rubble, and lagoon slopes, sheltering by day and crossing open bottom at night between sponge meals.
Range: Tropical Indo-Pacific and Red Sea, east to Hawaii and French Polynesia.
Behavior: Almost strictly nocturnal; crawls like any dorid until disturbed, then swims free with rolling flexes of its flared crimson mantle. Lays a rose-shaped pink egg ribbon on hard bottom.
Diet: Sponges, favoring chemically defended species whose compounds it stores for its own protection.
Size: typically around 0.25 m; documented up to 0.6 m (body length; most individuals run 20–30 cm).
How to behave around one
If the swimming display happens, enjoy it — but never lift, prod, or fan an animal loose to force a performance, and leave the egg roses unhandled.
Conservation
Not formally assessed; conspicuous size makes it a frequent harassment victim, which responsible operators actively brief against.
Charted sites known for them
Watch
From the official channels
Best Places to Dive with Whale Sharks
Outrageously Tiny Fish
Sink or Swim? with Monét X Change | Monterey Bay Aquarium
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