Fish Eating Spiders in a Garden Fish Pond... it's true

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Dear Mr Tony

I see that your email address says Pond Prof and so I wonder if you can help me.

I have a small pond with about 6 goldfish and a few guppies. The pond is located around shrubs and plants.

Recently I went to look at the pond and a spider was holding my goldfish by the side of the pond. I have also found a dead goldfish that looked as if
it has been eaten as the back part was exposed right to the spine.

. Today I was catching leaves and I noticed a spider actually under the water on the side on the pond, I have attached a picture.

Is there anyway to stop the spiders and get rid of them and are they poisonous to humans?

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Fish Eating Spiders in Garden Fish Pond Any help will be appreciated.

Thanks

Oscar

I was stumped by the question so I asked my good friend Peter J May to answer it. Here's Peter's response

Hi Tony
Weather is not too bad at the moment. Winter has been very cold with lots of freezing fog. France is getting it a very rough with 120mph winds at the moment.

RE spiders

Is this spider meant to be in the UK? I know there is a fish eating spider in the UK but it is very rare, but making a comeback! Check the link below:

http://news.bbc.co.uk/1/hi/wales/3150719.stm

I Googled fish eating spiders world wide and it seems they are all over the world. Check the pic of one in Florida below:

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http://www.flickr.com/photos/mistilittle/2447467154/

There are plenty in Africa as well. Basically a spider will consume anything its venom works on, so it will try to catch anything it feels it can handle. But once the prey is caught then it needs to be able to digest it. Spiders dont eat as such; they spew out digestive juices and suck it all back in again. Check out the bit of an article below:

"Nearly all spiders use venom to immobilise their prey before feeding. This makes it easy for them to feed on otherwise dangerous animals. Some Crab Spiders will catch Bumble Bees far heavier than themselves.

However the prey is caught it needs to be eaten and spiders, practice what is called external digestion. This means that enzymes and other digestive juices are injected or spat into the preys body. The soft tissues are broken down by these juices and sucked up by the spider. For spiders, soup is the only thing on the menu. Some spiders such as tarantulas and many of the orb-web spiders use the teeth on the basal segment of the chelicerae to mash their prey while they are feeding. In these cases all that remains after the spider has finished is a small dark blob of cuticle. Smaller spiders, especially those that feed on larger prey such as the Thomisidae bite only a small hole in the cuticle of their prey and suck the juices out through this. In this case what is left is a pretty intact shell of the prey animal.

While most spiders feed on invertebrates most of the time, they will take vertebrates when they can. Reports of Dolmedes catching small fish several times her own weight, of Leucorhestris taking small lizards up to its own weight and of Lycosids and Pisaurids catching tadpoles and small fish are fairly well documented. Evidence of large spiders taking small birds is also known in the tropics. Tales of tarantulas taking snakes in the wild are harder to verify though the first description of them doing so was written by the Roman Pliny 2000 years ago. However there is no doubt they will take them in captivity and therefore probably would take them in the wild when the opportunity arrives. In captivity tarantulas have been recorded killing and eating 30cm pit vipers and 45cm rattlesnakes as well as frogs and lizards.

Stranger still, in 1924 Reginald Pocock described finding a Poecilotheria regalis feeding on a rat in India, though no mention is made of whether the spider actually killed the rat. Strangest of all is a tale from Australia written in 1919 by a Mr Chisolm. He describes finding a chicken that had been killed and dragged 16 metres (50 feet) to a burrow by a Barking Spider Selenocosima spp.. The chicken was much to big to be puled into the hole and was found with one leg down the hole with the spider hanging on to that leg."

RE: Are they venomous? All spiders have venom and the bigger they are the bigger the bite. Although saying that, the most poisonous spider to humans, the Black Widow, is tiny. But then again, its venom doesnt affect dogs or cats.
So just in case, avoid big spiders incase you react to its venom - is a good rule. Although our garden spiders are meant to be harmless, if I get bitten by one, its like getting stung by a hornet for me. My wife reacts to a spider bite too, but we havent figured what spider it is! But we know its Italian and lives in Venice! It didn't kill her mind. It just made foot look like a football.

Maybe we should organise a spider website? They are very interesting.

All the best
Pete