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Ask Your Weird Animal Questions: The Largest Spider in the World

Weird Animal Questions got a new kind of query this week when a reader sent us a photo of a peculiar creature and asked for help identifying it.

It turned out to be so much fun to answer that we’re starting a “What’s in Your Yard?” feature: Send Weird Animal Questions your pictures of unidentified creatures, and we’ll try to ID them for you. After all, it’s nice to know your neighbors—especially if they bite.

Now, since this is an all-arachnid week, get ready for questions with legs.

Our first reader photo involves an itsy-bitsy spider.

A photo of a Spinybacked orb-weaver spider.
A spiny back orbweaver spider (Gasteracantha cancriformis) on its web in Everglades National Park, Florida.
Photograph by Scott Leslie, Minden Pictures/Corbis

I live on Grand Cayman Island. I love to shoot pictures of insects, and I wanted to know what you call this type of spider.  —Giuseppe Montisci

We got a bead on this species from Jo-Anne Nina Sewlal, an arachnologist at the University of the West Indies.

“Both photos are of the species Gasteracantha cancriformis,” aka the spiny back orbweaver,  Sewlal says in an email.

You might not see this harmless spider, but you may see its distinctive web. If you did, says Sewlal,”you would see short tufts of thick white silk along the frame of the web, so that it looks like a dashed line.” This decoration is known as the stabilimentum.

The function of these tufts isn’t clear, but the University of Florida’s website says they’re meant to make the webs more visible, so that birds are less likely to destroy them.

A photo of a goliath bird-eating spider.
The Goliath bird-eating spider (Theraphosa blondi) is the largest spider in the modern world.
Photograph by Piotr Naskrecki, Minden Pictures/Corbis

What’s the biggest spider in the world? —siddekh k v

This question stems from a story on the world’s largest fossil spider, a one-inch-long (2.5-centimeter) Nephila jurassica found in 2011 in Inner Mongolia.

And here’s the answer: The largest spider in the modern world is the Theraphosa blondi, aka the Goliath bird-eater: a quarter-pound tarantula that eats mice as well as the usual insects—and yes, the occasional bird. (See video: Huge spider)

“I wonder if the male spider is aware that mating can lead to death.” —Shanthi, Netherlands

A bit of anthropomorphic angst over a creature fated to be cannibalized by his mate is understandable, hence this question from a story on male dark fishing spiders.

Steven K. Schwartz, a behavioral ecologist at the University of Nebraska-Lincoln who led the study on this male self-sacrifice, says via email that “asking what other animals ‘know’ or ‘are aware of’ is a complex area of animal behavior and psychology.

“In short,” he writes, “we cannot determine what animals ‘know,’ but we can study what animals do (i.e., behavior).”

In his latest study, Schwartz and his team found that all the males are cannibalized after mating. Yet this doesn’t seem to reduce sperm competition, since females will mate again.

Maydianne Andrade, an evolutionary biologist at the University of Toronto Scarborough studies Australian redback spiders—a species in which the female nibbles on the male during a first copulation “so the male is partly digested,” Andrade says via email, yet returns to repeat the act.

From an anthropomorphic perspective, then, the males “know” what’s coming—they’re going to be eaten—”and they go back for more.”

“An evolutionary biologist such as myself would argue that, if these spiders are able to ‘feel’ anything, being eaten by the female should make them feel pleasure,” Andrade writes. “To some extent, our emotions and feelings are in service to our evolutionary fitness.”

The immediate thought is: How big is this spider? —Garrick Meadows

You couldn’t ask a smarter question when you come across a story about the world’s biggest, strongest spider webs, some of which span 82 feet (25 meters). These were first documented by National Geographic grantee Ingi Agnarsson and his team.

And the webs aren’t just huge, they’re stronger than the silk of any other spider, and twice as elastic. (Related: A spider’s web that spans rivers made from the world’s toughest biological material.)

Yet the weaver, the female Darwin’s bark spider, is only about as big as the buttons on your shirt—around 0.8 inches (2 cm) long.

Got a question about the weird and wild animal world? Tweet me or leave me a note on Facebook.

Comments

  1. Catherine Scott
    Canada
    June 29, 10:52 am

    To Renate:

    Western black widows (Latrodectus hesperus, which I’m guessing is the species you have, being in California) do sometimes eat prey that is already dead. Here is a report from the journal of arachnology: http://www.jstor.org/sici?sici=01618202%281981%299%3A1%3C109%3E2.3.TX

  2. Chun Xing Wong
    Sabah, Borneo
    June 24, 10:55 pm

    I have another weird animal question to ask.
    There are insects and spiders everywhere except in the sea. Why is there no insects and spiders in the sea ?

  3. karina feo
    uruguay
    June 23, 10:24 pm

    muy interesante publicacion sobre aracnidos. quisiera saber si alguna especie es mortal para el hombre? desde ya muchas gracias

  4. Renate
    Santa Cruz, California
    June 23, 10:17 pm

    Do you have any information whether black widows scavenge?
    I’ve had a very hungry black widow as pet (she laid five successive cocoons with 100-200 babies each) and once I saw her pick up a dead fly from the bottom of her cage and hang it into her web. She then proceeded to wrap it and suck it dry as she would have with live prey. I looked for mention of this behavior on the net, but did not find any. Are black widows known to scavenge?