Endangered spiders bred in captivity for first time

One of the rarest spiders has been bred in captivity in what is believed to be a world first.

An adult female Desertas wolf spider with young on her back - one of the rarest spiders has been bred in captivity. Picture: Bristol Zoo/PA Wire
An adult female Desertas wolf spider with young on her back - one of the rarest spiders has been bred in captivity. Picture: Bristol Zoo/PA Wire

More than 1,000 Desertas wolf spiderlings, classed as critically endangered, have hatched at Bristol Zoo Gardens.

Keepers have hand-reared some of the spiderlings from tiny eggs as they are so precious.

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They currently measure just 4mm in diameter but will grow to be huge black and white adults up to 12cm in size, with a 4cm body.

The species is currently found in one valley on Desertas Grande, one of the Desertas islands near Madeira, Portugal.

There is believed to be a single population of just 4,000 adult spiders left in the wild and it is hoped that some of the spiderlings can be returned to their native island in the future.

Mark Bushell, curator of invertebrates at Bristol Zoo, travelled to Desertas Grande last year and collected 25 Desertas wolf spiders to breed.

“Because this was the first time this species had ever been taken into captivity to breed, it was a steep learning curve,” Mr Bushell said.

“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.

The spiders are classified as critically endangered on the International Union for Conservation of Nature’s (IUCN) red list of threatened species.

They are under threat from habitat loss due to invasive grass binding the soil where they burrow, blocking their natural shelters.

Bristol Zoo has joined Instituto das Florestas e Conservacao de Natureza (IFCN) and the IUCN to develop a conservation strategy to protect the spiders.

As part of this effort, Mr Bushell collected the spiders to be brought back to the zoo and bred as a ‘safety net’ population.

One of the female spider’s eggs sac broke so eggs were carefully transferred into a miniature incubator for rearing.

Once the eggs hatched, they were placed in 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 points.

“Establishing the world’s first captive breeding programme for this species is a fantastic step towards protecting it for the future,” Mr Bushell added.

“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.”

Horticulture experts from the zoo hope to visit Desertas Grande to work with park rangers in a bid to control the invasive grass and help restore the original landscape.