3 questions on1
DO MAYFLIES FLY
ONLY IN MAY?
No. Worldwide there are over 3,000
species that appear at various times
of year, though one of Britain’s most
common mayflies, Ephemera danica,
does tend to emerge this month. It
alsofliesinJune.Theadultsofthis
specieshatchenmasseinwarm
weather,risingoutofrivers in
greatblizzards.A bighatch is
a bonanzaforinsectivorous
predators:swallows,
martins,wagtails,ducks,
moorhens,troutand
otherfish.2
WHY EMERGE ALL AT
ONCE LIKE THIS?
When conditions are just right, the
synchronised hatching of mayflies
can be a dramatic spectacle. Probably
the largest hatch on Earth happens in
midsummer at a few rivers in central
Hungary, and has been made famous
by wildlife film-makers (there’s a short
video on BBC Earth’s YouTube channel).
Mass emergence is a strategy known
as predator swamping. Though many
mayflies get eaten, the sheer number
in the air together ensures that enough
survive the army of hungry beaks and
mouths waiting for them.3
IS IT TRUE MAYFLIES
LIVE JUST ONEDAY?
The brevity of a mayfly’sexistence
is commemorated initsoldEnglish
name: dayfly. Its solepurposeisto
find a partner and mate,thenit dies
(in the case of the female,afterfirst
laying eggs). By evening,theriver
surface may be litteredwithcountless
shimmering corpses.Butthisisjust
the adult stage of thelife-cycle.Nearly
all of a mayfly’s life (whetherit’sweeks,
months or even overa year)isspentas
an aquatic larva, scavengingdebrisor
grazing algae on the bottom.
Ben HoareShort-lived may ies
GENETICS
Are elephant
shrews more
elephant, or
more shrew?
I
f it looks like a shrew, moves like a
shrew and snuffles like a shrew, it is
a shrew, right? That’s what zoologists of
the 1800s thought. Before DNA profiling,
physical characteristics were the best way
of discerning animal relationships, so
elephant shrews were placed squarely in
the shrew family. But genetic evidence has
revealed that they evolved independently
in Africa, and instead puts them in
their own order. This makes them more
closely related to elephants, aardvarks
and manatees than to shrews – or even to
rodents and rabbits. Still, with little furry
bodies and snouty noses, they do at least
look like shrews. As such, they are an
example of convergent evolution – where
similar physical characteristics arise
entirely independently, due to adapting
to similar environmental pressures or
evolving to fill a similar niche. In fact,
these rather adorable animals are more
shrew-elephant, than elephant-shrew.
Ellen Husain
Though a fraction
of the size, elephant
shrews have much in
common with their
large namesakes.BBC Wildlife 87Q&A