Scalloped hammerhead

The scalloped hammerhead (Sphyrna lewini) cannot be mistaken for anything else: its head extends sideways into a wide, mallet-like blade – the cephalofoil – whose front edge carries the distinctive notches that give the species its name. The slender, 2.5–3 metre shark's strange head is no ornament but a super-sense organ: with eyes placed at either tip it sees almost all the way around, and the Lorenzini ampullae concentrated under the head detect the faintest electrical signals of its prey's muscles – even of rays hidden beneath the sand.

Scalloped hammerheads are famous for gathering by day into spectacular schools of up to several hundred around offshore reefs and seamounts, then heading off alone to hunt at night. In the Red Sea the big schools appear at the remote offshore reefs – the Brothers, Daedalus – mainly in summer. The species is listed as critically endangered by the IUCN: fishing for its fins has wiped out much of the global population, which makes every sighting of a live hammerhead a genuine treasure – and the Red Sea's protected waters an important refuge.

Around Hurghada, honestly, encounters are rare: your best odds are at the deep, current-swept outer reefs – Umm Gamar, Carless Reef, the Small Giftun wall – typically early in the morning, scanning the deep blue. The hammerhead is decidedly shy: the noise of bubbles usually drives it away, so it almost never approaches divers. If that unmistakable silhouette does appear, stay calm and don't swim towards it – just watch and savour a moment most divers never get in their entire diving career.