Rusty parrotfish

The rusty parrotfish (Scarus ferrugineus) is the Red Sea's and the Arabian Gulf's very own parrotfish – you will not meet it anywhere else. It takes its name from the rusty-brown colour of females and juveniles, while mature males wear a completely different outfit: blue-green bodies with a glowing yellow patch and turquoise scribbles across the cheeks. The "parrot" part is about the mouth: its teeth are fused into beak-like plates used to rasp algae off the coral rock.

On a dive you often hear it before you see it: the loud, rasping crunch of the beak carries far underwater. Along with the algae it bites off chips of coral rock, which its throat teeth grind to flour – and the indigestible limestone leaves its body as fine sand. Parrotfish are thus the reef's most important "maintenance crew": by mowing back the algae they clear space for new corals, and as a by-product they spread sand across the lagoons.

Around Hurghada this is one of the most common parrotfish: it grazes everywhere in the shallow coral gardens, keeping snorkelers company the whole time. It works non-stop by day – just follow the crunching sound on the Giftun or El Fanadir plateaus. On a night dive you see a completely different animal: it sleeps motionless in a coral recess, often wrapped in a transparent mucus cocoon.