World first breeding
of one of the rarest spiders on Earth
One of the rarest
spiders on earth has bred at Bristol Zoo Gardens in a world first.
Over 1,000 tiny
Desertas wolf spiderlings have hatched in the Zoo’s Bug World. So precious are
the babies that some have even been hand-reared by dedicated keepers from tiny
eggs.
The hatchings are a
huge boost for the species which is only found in one valley on one of the
Desertas islands, near Madeira, Portugal. There is thought to be a single
population of just 4,000 adult spiders left in the wild – an alarmingly small
number for an entire invertebrate species.
It is hoped that
some of the spiderlings can be returned to their native island in the future to
boost dwindling numbers in the wild.
Desertas wolf
spiders are classified as Critically Endangered on the International Union for
Conservation of Nature’s (IUCN) Red List of Threatened Species but are not
protected by any specific legislation.
The baby spiders are
just 4mm in diameter but grow to be huge, impressive-looking black and white
adults up to 12cm in size with a body size of 4cm. They are under threat from
habitat loss due to invasive grass binding the soil where they burrow and blocking
their natural shelters.
Bristol Zoo has
joined forces with Instituto das Florestas e Conservação de Natureza (IFCN) and
the IUCN to develop a conservation strategy to protect the species in an effort
to prevent it becoming extinct.
As part of the vital
conservation effort, Bristol Zoo’s Curator of Invertebrates, Mark Bushell,
travelled to Desertas Grande last year with Zoo vet Richard Saunders and
collected 25 Desertas wolf spiders to be brought back to the Zoo to breed as a
‘safety net’ population.
The effort has been
a great success, as Mark explains: “Because this was the first time this
species had ever been taken into captivity to breed, it was a steep learning
curve. After some of the female spiders were mated, it was an anxious wait to
see if they would produce egg sacs. We were thrilled when they did, and to see
the tiny spiderlings emerge was fantastic – a real career highlight.”
Such was the
keepers’ dedication, that when one of the female’s egg sac broke, eggs were
carefully transferred into a miniature incubator for rearing. Once the eggs
hatched, they were put into separate containers with sterilised soil, kept in
quarantine and individually fed with fruit flies.
Bristol Zoo now
plans to send hundreds of the tiny spiderlings to other Zoos in the UK and
Europe to set up further breeding groups as part of a collaborative
conservation programme for the species.
Mark added:
“Establishing the world’s first captive breeding programme for this species is
a fantastic step towards protecting it for the future. It is a beautiful and
impressive creature but its natural habitat is being altered by invasive
plants. There are simply not enough rocky and sandy areas of habitat left for
the spiders to burrow and hide in. The result is a deadly game of musical
chairs, whereby the spiders are competing for fewer and fewer burrows.”
Mark added: “In
addition to the loss of habitat, one single catastrophic event could wipe out
the species entirely. Now we have successfully created a ‘safety net’
population here at Bristol Zoo to help safeguard this impressive creature for
the future.”
In future it is also
hoped that Bristol Zoo’s team of horticulture experts can visit Desertas Grande
to work with park rangers to control the invasive grass which is destroying the
spiders’ habitats and help restore the original landscape.
Bristol Zoo Gardens
is a conservation and education charity and relies on the generous support of
the public not only to fund its important work in the zoo, but also its vital
conservation and research projects spanning five continents.
For more information
about visiting Bristol Zoo Gardens, visit the website at www.bristolzoo.org.uk or phone 0117 974
7300.
Peter Dickinson
Independent International Zoo Consultant        |
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