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Sticker of Fen raft spider
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Fen raft spider

Dolomedes plantarius
Eats: Other bugs and small animalsSpidersPonds, rivers and shores8 legsNot an insect, but a bug cousin

The fen raft spider is a big dark brown or black spider with white stripes along its sides. It lives at the edge of ponds and ditches in wet fens. It can run across the water without sinking and even dive under it.

Fun fact: spiders are not insects. Insects have six legs, spiders have eight. Everyone calls them bugs anyway!
Lives in
Europe, including Estonia, by clean ponds and ditches in fens and wet meadows
Length
2 cm (0.79 in)
Top speed
about 1.7 km/h (1.1 mph)
On foot, estimate
Can it hurt you?
Harmless
What does it eat?
It hunts water animals like pond skaters, dragonfly larvae and other spiders, and even small fish and tadpoles.
For real!Photo of Fen raft spider
Picture by Helen Smith. CC BY-SA 3.0, via Wikimedia Commons.

How big is it?

How long is it?

Fen raft spider about 2 cm long (0.79 in)A grain of rice about 6 mm (0.24 in)A toy building brick about 3.2 cm (1.3 in)A crayon about 9 cm (3.5 in)
as long as 3 grains of rice in a rowcould run across a dinner table in 2.1 secondsmoves 24 times its own body length every second

How big is Fen raft spider compared to YOU?

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How fast is it?

cool stuff

Fun facts

1

It feels tiny ripples on the water with special hairs on its legs, and that is how it finds prey.

2

The mother carries her egg sac under her body for about three weeks and dips it in the water so it does not dry out.

3

Before the babies hatch, she builds a tent-like nursery web and guards them there.

4

It has become rare in many places, because its wet homes are disappearing.

you asked

Most asked questions about Fen raft spider

?Can the fen raft spider walk on water?

Yes. It runs across the surface of the water, and it can also climb down plants to go under water.

?How big is the fen raft spider?

Big females have a body of about 2 centimetres, and with legs they are about 7 centimetres across.

?What does the fen raft spider eat?

Water bugs, dragonfly larvae, other spiders, tadpoles and even small fish.

For bug experts

Scientific name
Dolomedes plantarius
Named by
Clerck, 1757
Group
Spiders
Family
Dolomedidae
Classification
Arachnida > Araneae > Dolomedidae
Lives on
Europe
Also known as
Great raft spider

Where the facts come from

  1. Great raft spider (Wikipedia, CC BY-SA 4.0): what it looks like, where it lives, what it eats, sizes and fun facts, retold in simple words.
  2. Picture by Helen Smith. CC BY-SA 3.0, Wikimedia Commons. The round sticker of this bug is cut from the same picture.

If we got something wrong, sorry, we are bug fans, not a science journal. Tell us at [email protected] and we will fix it.

More from the same group: Spiders

Also at home here: Ponds, rivers and shores