5 Badass Spiders That Kill and Eat Fish

By Carl Engelking | June 18, 2014 4:00 pm
dolomedes facetus

Dolomedes facetus captured this pond fish in a garden pond near Brisbane, Australia. Credit: Peter Liley

Life is not easy for a fish. Death can arrive in the twitch of a gill from bears, eagles, bigger fish — or a puny arachnid.

Spiders, it turns out, prey on fish far more than has been previously appreciated, and a new review study documents fish-hunting by spiders on every continent except Antarctica.

These spiders come from five main families sure to strike fear into many a minnow. Without further ado, five badass fishing spiders:

1. Pisauridae

Species of spiders belonging to this family are by far the most adept at catching a swimming meal, and more than 80 percent of spider-on-fish incidences in the survey involved this family. These foraging spiders do away with a web altogether and prefer to swim, dive and even walk on the water’s surface to prey on small fish and insects.

The most notable killers in this family belong to the genus Dolomedes, known as fishing spiders or raft spiders. According to one report, a single Dolomedes spider, which wisely established itself next to a fish tank within the Steinhart Aquarium in San Francisco, killed and devoured numerous fish in just a few days.

Dolomedes spiders were also spotted at an Oklahoma fish-rearing pond engaging in “wasteful killing,” or dispatching fish even when their appetites were satiated. Now that’s cold-blooded.

Here, the six-spotted fishing spider (Dolomedes triton) seen in action:

2. Ctenidae

Two species of spiders in this family (belonging to the genus Ancylometes) are nocturnal, big-bodied divers. They can submerge themselves for 20 minutes to an hour, relying on air bubbles trapped on hairs surrounding their book lungs.

While diving, they’ll catch fish, inject them with a lethal venom and consume them on the surface. The largest spider in this genus has a leg span of 7 inches, so frogs, tadpoles and lizards are also fair game.


A male of the genus Ancylometes caught this fish near Cuyabeno Wildlife Reserve, Ecuador. Credit: Ed Germain

3. Lycosidae

This family includes the pond wolf spider, which swims in the rice fields and swamps of Asia. It also has a bit of a Napoleonic streak: It’s one of the smallest spiders, just 1 centimeter in length, observed catching a fish in the wild. The diminutive spider has demonstrated its skill numerous times in the lab as well.

4. Trechaleidae

This family is a bit of a black sheep among fishing spiders — they aren’t as highly skilled as members of the other families; they don’t chase their prey across the water, and they are incapable of diving. Instead, they’ll plant their hind legs on a stone or a plant and rest their front legs in the water.

But they make do with their lazy approach, feeding on a diverse array of creatures including insects, shrimps, fish and frogs.

Trechalea spider

A spider of the Trechalea genus eating a fish in Colombia. Credit Solimary Garcia Hernandez, Universidade de Sao Paulo

5. Liocranidae

The most unlikely incidence of fish hunting occurs in this family. These spiders are primarily terrestrial, and less than 1 centimeter in length. However, researchers in France observed a spider from this family catching a tiny trout about 2.8 times its size.

Researchers say this is the only account of fish-eating from this family, so it may have simply been a peculiar chance event.


BONUS SPIDER: The Diving Bell

Though not a part of the “Big Five” families, the diving bell spider is perhaps the most famous of fishing spiders — and is the only known species of spider to live entirely under water.

This spider constructs “diving bells,” or dome-shaped underwater webs, between aquatic plants. When diving bell spiders get hungry, they hunt tiny fish by injecting them with a potent venom that instantly kills.

Here’s the diving bell spider in action:


Researchers say there are in total at least eight families of spiders known to consume fish. And much remains to be learned: we still don’t know how important fish predation is for the spiders’ survival, or the role their taste for fish plays in aquatic food chains.

However, this is for certain: It’s no fun being a small fish in a big pond.


CATEGORIZED UNDER: Living World, top posts
  • DirtAddsHP

    very nice

  • Stefano Lottini

    Please, would you correct that “insect” that somehow made its way to the first sentence?

    • Inis_Magrath

      Arachnid. You’d think Discover would have writers who know better.

    • XFuncCarter

      Sometimes what is correct in colloquial English isn’t scientifically correct.

      That’s okay. The first sentence was meant to be colloquial, and technically it doesn’t identify a spider as an insect anyway.

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  • Jon Mendoza

    Well, you know what they say, “Give a spider a fish, and it can eat for a day, teach a spider to fish…and it takes over every continent!”

    • Leon Davis

      Not in the US. Obama put all the fishing spiders on food stamps. Now they just lay around and eat $5 bags of chips.

      • Wiggymaster

        Storm Trooper: “Look sir, trolls!”

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    Oh, ya, it surprised me to discover that mantises will eat mice, rats, and snakes and now spiders eat almost the same things. What’s next?

  • Wiggymaster

    Well, no sleep for me tonight.

  • Dirk van Toor

    I have limited affiliation with fish. Other than that they taste quite well, that is and that I consume them with gusto.
    Spiders on the other hand, cause in me an uncharacteristically violent reaction, which generally ends with a thoroughly flattened arachnid.
    I know better!
    Spiders are useful and kill more pest than they are themselves.
    I try to halt myself, but the elimination of an abhorrent eight-legged killing machine just feels too good.
    It does help that I was once bitten by a spider (brown recluse) and had to
    go through extensive reconstructive surgery to deal with that particular bite.
    I just mortally hate spiders.
    I have no admiration of their morphology. To me they are just ugly.
    I have no feelings of esthetical admiration or affiliation with them.
    They are abhorrent to me and are likely to meet with my heavily planted foot on them.
    My limitation. I know and I readily admit that….. but I just do not like spiders in any way, shape or form.

    • http://blogs.discovermagazine.com John Kuipers

      It sounds like a new book to me “I hate spiders” by Sam I am.

    • Terry Simpson

      Actually, fish taste GOOD, not well. They can be well done, of course, but that makes them kind of tough. And who wants a tough fish? I agree, however, that it is easier to hate spiders than it is to hate snakes.

    • Don’t Even Try It!

      I prefer my spiders with 4-wheels and on twisty roads!

  • scrumble

    Can someone explain why this is plastered over plenty of media outlets as “Fish-eating spiders discovered by scientists”.

    Can I expect tomorrows headlines to be “Engineers invent wheel”?

  • Divaselinaselin

    Spider can survive in water??
    But i though if the family of insects they cant survive in water. Not above but in the water.

    • mbkeefer

      They are not related to insects. Does that solve your problem?

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  • DodgeMiniVan

    Why did Noah have to include tow of every known species of insects, snakes and animal that are dangerous and harmful to humans? Please don’t give me a Biblical explanation as I consider the Bible to be only a great history book.

  • mariajlandreth

    My Uncle
    Riley got an almost new red GMC Canyon just by some parttime working online
    with a laptop. visit their website F­i­s­c­a­l­p­o­s­t­.­C­O­M­

  • Keith Stepp

    I just found a fairly good sized spider living in my aquarium. He was underwater when I spotted him. The body was the size of a good sized bean and he was furry. At first I thought he was a ball of freeze dried brine shrimp and was reaching in to pick it out when I realized it was a spider. He was basically the color of the shrimp. Sort of a beige. I have no idea what kind of spider he was or how long he has been in my tank. Anyone else had this experience?


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