Home

PETER FROST meets the great raft spider.

The Broads National Park Authority can be justifiably proud of its work on biodiversity, but here is a story that might get a mixed welcome, particularly from Arachnophobes – those who hate spiders.

Britain’s rarest, largest and most spectacular spider has been introduced to the Norfolk Broads after an intensive captive breeding programme.

A thousand hand-reared fen raft baby spiders or spiderlings have been released on the Mid-Yare nature reserve in an effort to generate new populations of this vulnerable species in Norfolk, where they are now restricted to a single site.

images (4)

The fen raft spider, (Dolomedes plantarius) is Britain’s biggest spider and can grow to the size of your hand with a body length of  an inch (23mm).

image0001

The raft spider can literally walk on water to catch its prey but owing to deterioration and loss of wetland habitats, its population has suffered.  It is listed as Vulnerable on the IUCN’s Red List of Threatened Species and as Threatened in the UK Red Data Book.

Ecologist Dr Helen Smith,(pictured below) who co-ordinates the Fen Raft Spider Species Recovery programme for Natural England, has reared 5,000 spiderlings in her own kitchen over the last three years.

download (7)

“I think everyone who does captive rearing gets very attached to them,” she said. “The baby spiders each have their own test-tube to avoid them eating each other so you have to devote yourself to feeding them for three months. We achieve survival rates of around 90% over this period, when survival in the wild would be very low.

“The Mid Yare reserve is a very good habitat and the spiders will be able to spread easily from the release site. It’s very exciting to be able to establish a new population in the heart of the Broads.”

This article appeared in the now defunct magazine Canals, Rivers and Boats. The expanded version below,appeared in the Morning Star.

Incey wincey spider

PETER FROST says if you want to know all about spiders just look on the web.

The fen raft spider, (Dolomedes plantarius) is Britain’s biggest native spider and also one of the rarest beasts in the whole of our countryside.

This spider can grow to cover a small human hand with a body length of an inch (23mm.) and with legs spanning three inches (70mm.)

It can literally walk on water to catch its prey. It lays in wait at the waters edge with its front two feet resting on the water feeling for vibrations.

images (5)

When the prey – insect or tiny fish – is within range it skates across the waters surface for the kill.

Loss of wetland habitats has almost bought the raft spider to extinction but now work by the Broads National Park and many other conservation bodies has saved it from extinction and set the species on the road to recovery in Britain.

Up to now the fen raft spider was only found on three wetland sites in the UK.

Most important site is at Redgrave and Lopham Fen National Nature Reserve (below) in East Anglia where it was first discovered in Britain in 1956.

Redgrave and Lopham Fen

It was here that TV environmentalist David Bellamy studied the spider when a student – it was the subject of his degree thesis.

The other tiny populations are on the Pevensey Levels in Southern England and at one further site on a canal in South Wales.

Dolomedes plantarius is listed as Vulnerable on the Red List of Threatened Species and as Threatened in the UK Red Data Book. This makes it one of our most likely species for extinction.

Now conservationists are fighting hard to save this remarkable animal.

It has now been introduced to many new suitable sites in the Norfolk Broads after an intensive captive breeding programme.

A thousand hand-reared fen raft baby spiders or spiderlings have been released on the RSPB’s Mid-Yare reserve in the Broads National Park in an effort to generate new populations of this vulnerable species.

Thousands of the baby spiders have been released by their foster parents, who have patiently reared them in individual test-tubes over the summer.

The tiny spiderlings have been bred from the wild population at Redgrave and Lopham Fen.

Ecologist Dr Helen Smith, who co-ordinates the Fen Raft Spider Species Recovery programme devised the test tube rearing techniques.

In the wild female raft spiders incubate their eggs in their mouth holding the eggs upwards to gain warmth from the sun.

Helen has reared no less than 5,000 baby raft spider in her own kitchen over the last three years.

“I think everyone who does captive rearing gets very attached to them,” she said.

“The baby spiders are cannibals so each has to have their own test-tube to avoid them eating each other.

“You have to devote yourself to feeding them by hand for the first three months of their life.

“We achieve survival rates of around 90% over this period, when survival in the wild would be very low.

“The Mid Yare reserve is a very good habitat and the spiders will be able to spread easily from the release site. It’s very exciting to be able to establish a new population in the heart of the Broads.”

Between 2010 and 2012 nearly 12,000 spiderlings have been released to the wild to establish new populations in Norfolk and Suffolk.

For instance at Suffolk Wildlife Trust’s reserve at Castle Marshes near Lowestoft they have been breeding successfully this year, producing an estimated 50 nursery webs.

The aim of the nationwide programme is to secure the future of this species in the UK by increasing the number of populations from three to 12 by 2020.

 All you ever wanted to know about spiders but were too afraid to ask.

  • The fear of spiders – arachnophobia – is Britain’s commonest phobia.
  • Spiders are useful killing more insect pests than birds and bats combined.
  • There are more than 650 species of UK spiders.
  • Eight of our native spider species choose to live close to humans in domestic houses or gardens.
  • Good spider country can support as many as three million spiders per acre. Common meadow will have more than a million per acre.
  • Spiders have eight legs and no antennae. Insects have antennae and six legs
  • Spider silk – nature’s strongest fibre – is five times stronger than steel.
  • Hunting spiders have up to eight eyes in three layers.
  • Schoolchildren suggested sending spiders into space to see if they could spin webs in zero-gravity – they could.
  • Two species of British cave spiders never see daylight.
  • Like chameleons some spiders can change colour.
  • Spiders breed in autumn. Females get fatter to attract a male.
  • Some male spiders use their silk to weave a boudoir in which they deposit their sperm ready for a mate.
  • Money spiders fly using a woven silk parachute or balloon.
  • The false widow spider that arrived in Britain from the Canary Islands can give a nasty bite.
  • Black widows rarely eat their mate after breeding.
  • The world’s biggest spider – the giant huntsman – is more than a foot (300mm) across.
  • Spider-Man is not real.

End (200 words)

 

Advertisements

One thought on “Britain’s biggest spider

  1. Pingback: The Grey Zone | Ben's Blogs, Books & Pix

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s