Page 70 - BBC Wildlife Volume 36 #05

HUMPHEAD WRASSE

spectacle on this remote atoll, though at the time I didn’t Above: a male from humans, only great apes and ravens are known to
imagine I was going to be the last (more of which later). humphead use gestures in this way. Then again, fish are showing
wrasse and
There are many fascinating facets to the lives of themselves to be far smarter than they’re often given credit
Clockwise from top left: Alex Mustard/naturepl.com; Paul & Paveena Mckenzie/Getty; Tony Wu; Reinhard Dirscherl/FLPA
several bluefin
humphead wrasse. Around five years ago, scientists in trevallies hover for, as shown by Jonathan Balcombe’s recent BBC Wildlife
Australia noticed them forming hunting alliances, not with near a moray eel, feature (‘Minding Nemo’, August 2017).
other humpheads but with other species such as groupers. hoping to grab Humphead wrasse also have surprising sex lives. Most
any prey that it
These fish are stocky and can’t follow prey when it dashes to hatch as females, and then when they reach roughly 1m
disturbs.
safety inside the reef. A humphead, on the other hand, has in length and 15 years of age they undergo a sex change;
strong jaws that can shoot forwards and snatch prey from they stop making eggs and make sperm instead. The
hidden nooks. Together, a wrasse and a grouper make a phenomenon, known as protogynous hermaphroditism, is
dangerous pair. quite common among wrasse. In the huge wrasse family,
When a small fish darts out of sight, a grouper will often most of the 600 or so species are sex changers.
stop and wait for a humphead to cruise by. Then the grouper
sticks its tail in the air and gestures at the prey’s hiding place WONDERFUL WRASSE
by pointing with its head and shaking its body. On cue, the Wrasse live in shallow seas worldwide, and coral reefs are
humphead investigates and, with its movable jaws, reaches bustling with all sorts of species. Moon and sunset wrasse
into the reef. The result is, it might catch a meal or scare the dart around with colourful, cigar-shaped bodies. Slingjaw
fish out of hiding straight into the grouper’s waiting jaws. wrasse take protrusible jaws to an extreme, slinging their
This kind of inter-species cooperation is extremely jaws forwards in a tube that reaches half their body length.
rare in the animal kingdom let alone among fish. Apart Several species of cleaner wrasse are the coral reef’s
hygienists, picking off parasites, dead scales and skin from
visiting fish and sea turtles. To advertise their services,
SCIENTISTS NOTICEDWRASSE FORM cleaner wrasse flick their bodies from side to side in eye-
catching, gyrating jigs.
HUNTINGALLIANCES,NOTWITH OTHER The British Isles have their own colourful wrasse. Most
HUMPHEADS BUTWITH OTHER SPECIES. common, and the largest, are ballan wrasse. These can be
various colours, often deep red with pale blotches; the young
70 BBC Wildlife Spring 2018