Home » What is a Fen Raft spider and are they UK’s biggest spider?

THERE is a wide range of species of spiders, and the Fen Raft is one of them.

It is one of the biggest spiders found and here is what you need to know about it.

What is a Fen Raft spider?

Also known as the great raft spider, the Fen Raft spider is a European species that hunt for food on the surface of the water.

It is one of the largest species within its range of Pisauridae.

The female ones can have a body of 20mm in length and can take up 70mm with their legs.

It’s normally brown or black and has white or cream stripes along the side of its body.

CTB44A Fen Raft spider – Dolomedes plantarius, in the palm of a hand, carrying an egg sac.


CTB44A Fen Raft spider – Dolomedes plantarius, in the palm of a hand, carrying an egg sac.Credit: Alamy

They can live for about two and a half years.

Water is essential for their survival, hence that is why they are found mostly near lakes, rivers and maybe beaches.

Learn more about whether spiders remember you and if they have memory
How to keep spiders away while sleeping

Are Fen Raft spider’s the biggest in the UK?

The Fen Raft spider is the biggest kind of spider found in the UK, and also one of the rarest.


It was found in three sites across the UK and this rarity listed it as endangered.

Because of this, it is protected under Schedule 5 of the Wildlife and Countryside Act 1981 in England and Wales and under the Nature Conservation (Scotland) Act 2004.

The sites in which the Fen Raft was found were the Redgrave and Lopham Fen in Norfolk, the Pevensey Levels in East Sussex and the Tennant Canal in South Wales.

You won’t find this spider near your home unless you live near aquatic life.

Since one of its musts is water, then it won’t really seek much dry places such as the corners of your house.

It would rather seek a pond to find its prey such as fish.

Are Fen Raft spiders poisonous?

If a Fen Raft spider bites you it will only cause you minor pain and swelling.

These are the only side effects of its poison.

I’m a size 26 and weigh 12st MORE than my man - we’re proud of our relationship
Millions of PlayStation owners could be owed 'up to £560 EACH'

It won’t lead to death unless an allergic reaction to the poison happens.

In the case where you feel unconsciousness, fever or other symptoms which you think are abnormal, seek medical assistance immediately.