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How To Be An Assassin February 21, 2010

Posted by Mrs Weird Scientist in Animals, Brain Power, Insects, Think About It.
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Credit: Video generously provided by Anne Wignall of Macquarie University.

Imagine you’re a hungry insect. To get your next meal, you need to be a true assassin, using stealthy tactics to capture your prey. Well if you were an assassin bug, then your plan might read like this:

1. Slowly approach your prey

2. Tap the web before each step

3. Bounce around a bit

4. Grab some web strings

5. POUNCE

It might sound like a strange plan but it works! The assassin bug does all these bizarre movements to trick the spider into thinking it has an insect caught in its web. Once the spider is sure that it has its next meal, it scurries over to the assassin bug. But too bad for the spider, it will now become a tasty meal for this sneaky insect. To find out more about this peculiar bug, I chatted with Anne Wignall of Macquarie University in Sydney, Australia, who had some of her recent work published in the Journal of Ethology. Anne already knew that some bugs would hunt down spiders but she wanted to find out just how they did it! Anne explained to me:

When I heard that there was a bug that seemed to lure spiders toward them, I was instantly fascinated because it seems like such a crazy thing to do, when spiders are such dangerous predators themselves.

In fact, there is actually one more step in the assassin bug’s plan, which could come in at number six. Once the assassin bug grabs the spider, it sometimes will tap the spider with its antennae. Researchers think this might be a way to hypnotize the spider, making it harder to escape.

A World Of Assassins

The assassin bug in the video above is a species known as Stenolemus bituberus. But if you thought it was the only one, think again! Anne describes just how busy our world really is when you get outside:

There’s also lots and lots of other assassin bug species and insects that use stalking, deception, luring and other cool tactics to hunt other invertebrates, and we’re finding more all the time.

So this means there are way more bugs out there with incredible, assassin-like tactics to capture their prey. For example, Todd Blackledge of the University of Akron in Ohio has been investigating how wasps hunt spiders. He found that adult female wasps will capture spiders and sting them. Ouch! But that isn’t all. The wasp then lays an egg on the spider, which allows the wasp larva to eat the spider, helping it grow into an adult.

Your Garden: A Battleground For Bugs

Now that you’ve checked out the video above, you might actually be able to find one of these creepy crawlies in your garden. Anne suggests that if you live along the east coast of Australia, you should explore the trees and webs in your garden, where you might find an assassin bug battling it out with a spider. Just be glad that while those hungry bugs fight it out, you don’t have to go through anything quite so dramatic when you want to have lunch. In fact, make yourself a nice sandwich, grab your camera, then see what you can find in your backyard!

A Gentle Cat October 1, 2007

Posted by Mrs Weird Scientist in Animals, Cats, Easy As Pie.
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Sabre-Tooth Tiger

Credit: Colin McHenry

If you’re like me, you are perhaps super fascinated by vicious beasts of the animal kingdom. At the same time, my vivid imagination means that I do cringe a bit (or a lot!) when I think about these beasts attacking their prey. But are these animals with long, sharp teeth really so ferocious? Nope – they’re not necessarily as ferocious as we think!

The North American sabre-tooth tiger – now extinct – had some enormous teeth. In fact, if you picture two long, sharp kitchen knives, you’ll have a general idea of just how intimidating the tiger’s canine teeth were! It turns out, however, that the scary look of the teeth is somewhat deceptive. The tiger’s bite is actually a lot more gentle than scientists initially thought. It might even surprise you to know that the tiger’s bite is gentler than the bite of a lion. Why compare it to a lion? Well, it’s because the lion is one living animal that is very similar to the sabre-tooth tiger.

Computers Are Cool

By using computers to compare the intricacies of the tiger’s skull with that of a lion, it was found that the sabre-tooth tiger – formally known as Smilodon fatalis – has a rather light bite. Colin McHenry of the University of Newcastle, Australia looked at the skulls of lions and fossilized sabre-tooth tigers using computed tomography (CT) scans. McHenry and his team created three-dimensional computer models for a lion and a sabre-tooth tiger, which were then used to determine the bite strength for each animal. The results can be seen in the Proceedings of the National Academy of Sciences.

So, just how big of a difference was there? Well according to these models, a 250 kg lion can trigger a force of 3000 Newtons with its bite versus a 230 kg sabre-tooth tiger, which can produce a mere 1000 Newtons. A cool difference that researchers noted was that a lion can handle much more force generated by a struggling prey whereas a sabre-tooth tiger can’t withstand so much pressure and instead, would have been considerably injured.

Pouf, Be Gone

The ways that an animal kills its prey can lead to its extinction. How so? For the sabre-tooth tiger, it likely killed its prey by tackling it down to the ground, forcing its head down, immobilizing it and then snap – taking a quick bite to the prey’s neck. While a lion can capture smaller prey, the sabre-tooth tiger would not have been fast enough to conquer smaller, speedier animals. This means that when large prey were abundant, the tiger would be fairly well fed but when its preferred animals became scarce near the end of the ice age, the species soon became extinct.

Still, I don’t doubt that the sabre-tooth tiger could do some serious damage to its prey. It may have a gentle bite in comparison with a modern lion but I think I’ll stick with a cute, household cat. That’s one bite I can definitely handle!

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