Learn something about Steatoda!

Here you go, an excellent introduction to the spiders I work on, the false widows.

I should probably require all my students to watch it, because it strikes a good balance on something I struggle with: venom. I tell my students it’s medically significant, a bite can hurt, and the venom can make you sick, but at the same time I tell them I’ve never been bitten, I handle them all the time, and as long as you’re gentle, there’s no real danger.

Also interesting is the geographical difference. I’ve never seen Steatoda grossa or S. nobilis around here — it’s all Parasteatoda (I know, different genus), with some S. triangulosa and rare S. borealis in specific habitats. McEnery makes the interesting hypothesis that it may be the venom, that Steatoda generally makes a venom that’s significantly more potent against invertebrates than the venoms of native species, allowing them to thrive and take over.


  1. StevoR says


    Except, er, living in Oz, the spiders in my house tend to be Huntsmen spiders (Sparassidae formerly Heteropodidae) which are very welcome as natural moretin and harmless companions and Redbacks ( Latrodectus hasselti/i>) which despite being the local cricket teams namesake and icon are not given they can give a seriously sickening bite so I’ve heard.

  2. StevoR says

    ^ Sigh. italics fail. Sorry.

    Also that’s Mortein – a fly-and insect killing spray. Dunno how familiar folks outside of Oz are with that?

    Also yes, I presume this is for a mainly American (USA) even Northern American audience which is udnerstandable and fair enough albiet a lot of the planet willI imagine have diferent spider species in their homes.

    Not sure how widespread Steatoda species are generally, hmm… lessee :

    The spider genus Steatoda, in the family Theridiidae, includes about 120 recognized species, distributed around the world (including many cosmopolitan species which are found among human populations worldwide).[2] One common name is cupboard spider, for many species build their webs in dark, sheltered, undisturbed places around the house or garden, in sheds and garages, under garden furniture, compost bins, and the like. Signs of the cupboard spider include small white spots of spider droppings, like small splashes of paint, on the floor underneath the web.

    Source : https://en.wikipedia.org/wiki/Steatoda

    So, huh, maybe they are also living in my home too although I don’t specifically recall seeing any or seeing any mentions of them on local naturalist groups. Then again I also can’t honestly say I’ve really looked..

  3. StevoR says

    PS. We do also see the occassional Wolf spiders (Lycosidae)


    and Mouse Spiders (Missulena) :


    Outside in the Bush too as well as the wonderful Bird Poo spiders (Celaenia excavata) :


    in our local gardens – native and exotic – too..

    Plus some great Orb Weaver spiders and heir manifient often huge webs..


  4. Walter Solomon says

    So, do false widows prey on red imported fire ants like the southern black widow? We need all hands on deck to fight that scourge.

  5. birgerjohansson says

    Part of the charm of cats is that they bite and scratch you even if they like you. This would be a problem with all venomous animals.

    -So are there venoms that are more effective against invertebrates than small vertebrates? I assume venoms usually act on nerves.
    But a lot of things are “strongly conserved” since the last common ancestors, are really invertebrates and vertebrates so different at the lowest level that venoms need to evolve to be effective at distinct phyla ?

  6. says

    Yes, PZ, I watched the whole video. You are right. It is very informative. And, he is a good presenter. Yet, your vids are usually just as informative and interesting.

    Now, i have a comic that everyone here should see:

    Just guessing that PZ gets excited when 8 legs are involved. So I surmise that he switched from Octopi/cephalopods to spiders because he could still experiment with 8-legged creatures without all the hassle of huge tanks, short lifespans, and his Octopi crawling out of the tanks all the time.