Q&A
This month’s panel
We solve your
wildlife mysteries.
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More amazing facts at
discoverwildlife.com
BENHOARE
Editorialconsultant
ELLENHUSAIN
Wildlifefilmmaker
LAURIEJACKSON
Wildlifetourleader
HELENSCALES
Marinebiologist
GILLIANBURKE
Naturalist& TVpresenter
LAURENPHARR
Ornithologist
EDDREWITT
Naturalist
RICHARD JONES
Entomologist
H
ealthy tropical reefs look
like lush underwater
gardens, covered in rainbow-
hued hard and soft corals,
with psychedelic fish flitting
around. Corals get their
colours from single-celled
algae inside them, which
contain photosynthetic
pigments that harness the
sun’s energy and thus provide
food. What about the fishy
multitudes? Some evolved
colour as camouflage – for
example, the pink pygmy
seahorse hides in coral fans.
Cleaner wrasse use their blue-
and-yellow stripes to advertise
their services to other fish.
Meanwhile, fangtooth
blennies deploy colour for
deception – they mimic the
cleaners, but rather than
nibble parasites off visiting
fish, take bites of skin instead.
But when sea temperatures
rise, this ecosystem’s vibrancy
rapidly drains away. Heat-
stressed corals eject their
algae and lose colour, a
phenomenon called coral
bleaching. Helen Scales
H
overflies may be
renowned for it, but
many other insects do it
too, including bees, wasps,
beetles and other types of fly,
all of which land vertically
on flowers, helicopter-
style. But the best hoverfly
hoverers are those that guard
a 3D territory in mid-air. It
might be a shaft of sunlight
across a woodland path, a
sheltered open space against
a hedgerow, or a small
forest clearing. The resident
hoverfly will hang in the air,
stock still, a few metres
off the ground. Every now
and again, it suddenly
buzzes out sideways to
inspect an intruder or check
out a potential mate.
The front of a male
hoverfly’s head is virtually all
eyes – two huge hemispheres
that touch each other. This
gives the insect all-round
vision to monitor its
hovering position and track
the flight paths of other
insects crossing its precious
air space. Richard Jones
What makes coral reefs
so full of colour? Why do hover ies hover?
MARINE LIFE
ENTOMOLOGY
Coral digital composite: Georgette Douwma/Getty;
hoverfly: Michael Durham/NPL; mandrill: Thomas Marent/Minden/NPL
80 BBC Wildlife August 2020