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Males Can Sniff Out A Well Fed Female July 8, 2011

Posted by Mrs Weird Scientist in Animals, Brain Power, Insects, Think About It.
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11 comments

If they’re a male black widow spider, that is. Simply by taking a little saunter across the female’s web, a male black widow can sense if a female is hungry or not. Why does it matter? Because female black widow spiders have a rather freaky habit of eating the male after mating. It’s how they earned their dangerous name.

Now that’s one massive female black widow spider. You would almost think she’s been doing some seriously heavy weights at the gym. But nope, females are normally much bigger than males. Those males best watch out!

The Smell Of Safety

Males have developed this very useful technique, which tells them whether or not a female has recently eaten. But if a female is hungry, she would be more likely to cannibalize the male spider. They take a sniff of those silk strands and then decide if they want to proceed or scurry away. A new study discovered this interesting skill and published the findings in the journal Animal Behaviour. So, how do researchers actually go about testing something like this?

Feeding Time For The Ladies

First things first. The researchers fed a bunch of hungry female back widow spiders. Using a cricket neatly held between forceps, they rested it on the web and waited for the female to come over, wrap the cricket in silk and chow down. The females got one cricket each week. Yet, by the time the fourth week came around, they weren’t so hungry anymore and didn’t really want to eat the crickets.

I bet this female black widow spider is thinking: “Ah, the satisfaction from a good meal of crickets. I think I’ll accept the advances of the male spider perched nearby. Since I’m well fed, I probably won’t eat him after we’re done.”

Another bunch of female black widow spiders were starved for a few weeks. It apparently didn’t put their lives at risk, but they did get a bit smaller. Now, let’s find out what happened when a male was placed on the web of a well fed or a starved spider.

One Step, Two Step, Three Step…Four

Since the male spiders can pick up scents with their feet, they were able to figure out the difference from one female to another just by walking on the web. Normally, a male black widow spider has a special dance he does to court the female.

In this experiment, the males danced far more actively on the webs of well fed females. Smart dudes! If anything, dancing and mating would leave them ready to eat – not be eaten! Typically, they dance around for an hour or two, which sure shows their dedication to the purpose. They wave their legs and pluck and tap at the web in a unique way, so that unlike prey they show the female they are interested to mate rather than become dinner.

If Only I Had Such Powers

Now I have a strong sense of smell but definitely nothing like these male black widow spiders. It’s too bad because I’m really scared of spiders even though I know most are harmless. If I had my way, I’d be able to simply smell any spider from several meters away. That would give my timid self enough time to run!

No Fair! December 21, 2010

Posted by Mrs Weird Scientist in Animals, Easy As Pie.
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2 comments

Despite the exclamation above, I’m not throwing a temper tantrum. But I do get frustrated when I read news stories about science and think “Woah, this is really complicated.” It’s one reason I started this blog. To learn about a few more reasons, you can see an interview I did for the Charlotte Observer here.

Speaking of unfair things, if you read my last post and wondered if Tiko ever got off the toilet, well the picture on the right should answer your question.

His furry derriere is still planted firmly on the porcelain potty. He says it’s actually rather comfortable and he even had the audacity to ask me to serve him some liver treats and install a television on the wall.

I’ve already decided that if I ever start another blog, it will be called Weird Dogs.

Whale Poo Is Good For You September 12, 2010

Posted by Mrs Weird Scientist in Animals, Brain Power, Environment, Ocean, Tough Stuff.
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10 comments

In fact, it’s good for all living things.  Australian researchers recently found that whale poo is battling one of the planet’s toughest battles ever – climate change.  The poor whales previously had a horrid reputation.  Since they breathe out a common greenhouse gas known as carbon dioxide (CO2), they were disliked for contributing to global warming.  Estimates are that they breathe out 200,000 tonnes of CO2 a year.  Eep!  It isn’t surprising people had a bad opinion of them!

But there’s way more to the story than this one fact.  Let’s start with the basics and see how something so gross can actually be good for us all.  Major science geeks can read the full study results in the Fish and Fisheries journal.

Benefits Of Whale Poo

A young sperm whale gracefully swims in the Southern Ocean. A trip up to the surface might mean a poopy feeding for the hungry phytoplankton, helping to fight global warming. Image credit: National Oceanic and Atmospheric Administration (NOAA).

In the Southern Ocean, we’ve got an estimated 12,000 sperm whales.  They hunt down fish and squid for food.  Once digested, out comes all that poo.  Why should we care about whale feces?  Well, it contains loads of iron.  All of those whales poop out approximately 50 tonnes of iron each year.

What’s so special about the iron?  It’s a fabulously delicious food for phytoplankton, which are marine plants that exist up near the surface of the ocean.  These helpful plants like to take in CO2 from the atmosphere through a process called photosynthesis.

Better still is that the whales pop out their poop (even I chuckled as I wrote that) in a liquid form that’s close to the surface of the ocean, making it easier for the phytoplankton to access.  After, the whale dives down into the ocean, presumably feeling a little – or a lot – lighter!

Let’s Do The Math

First, we have to see how much CO2 gets sucked up by the plants, which is all thanks to the whale poo.  It’s 400,000 tonnes.  Now that’s twice as much as the 200,000 tonnes they breathe out through respiration each year.  The 200,000 tonnes is equivalent to emissions from 40,000 cars!

I got in touch with Steve Nicol of the Australian Antarctic Division to find out how the study all started.  He explained:

Our research was actually looking at baleen (krill eating) whales and the iron that they release.  The research was stimulated by some ideas raised by Victor Smetacek and we had the samples and the expertise here in Hobart to do the measurements necessary to test these ideas.

When I asked Steve what we can do to help, his answer was a simple one.  Simple but not necessarily easy to attain, especially given the attraction of whale hunting in many places around the world.  According to Steve:

Many populations of great whales are recovering fairly fast – some at about the maximum rate possible.  The best assistance we can give them is to avoid killing them – either accidentally or deliberately.

Don’t Judge Too Soon

I think an important lesson here is that we can’t judge too quickly and instead, should always look at the big picture.  When we first hear about all the CO2 the whales are putting out there, it’s easy to think badly of these massive sea creatures.  But with the Southern Ocean normally being a poor source of iron, the whales are making sure those phytoplankton are happily fed.  This way, the phytoplankton can do their job of taking out the nasty CO2.

Now, if only human poo had such fantastic capabilities.

Bartholomew Says Hello June 22, 2010

Posted by Mrs Weird Scientist in Animals, Brain Power, Deep Sea, Easy As Pie, Environment, Evolution, Ocean.
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6 comments

If this blobfish could talk, I think it would ask for us humans to give it some space. Maybe then it would have reason to smile. Credit: Greenpeace

Okay well, I made up the name Bartholomew and this interesting creature can’t really speak.  But if it could, I imagine it might say something like “Please leave me alone!”  So, just what is this odd, slimy thing and why would it want us to stay away?

Meet A Blobfish

With the formal name of Psychrolutes marcidus, the blobfish is definitely not the world’s prettiest fish.  It is, however, on the verge of extinction according to researchers at the University of York in England.  For blobfish, home is 800 meters into the ocean, just off the southeastern coast of Australia.

But unfortunately, excessive fishing with nets along the bottom of the ocean has jeopardized the well-being of the blobfish.  It starts with overfishing at less deep and murky depths.  After reducing populations up there, not much is left.

To compensate, we do something called bottom trawling, which takes us even deeper into the ocean.  Here, we are fishing along the sea floor.  It’s bad news for Bartholomew and all the other blobfish down there.  No wonder poor Bartholomew looks so sad.

These blobfish may look like your grumpy Great Aunt Martha but they're probably unhappy for another reason. Overfishing is threatening their livelihood. Credit: NOAA Alaska Fisheries Science Center.

A Day In The Life Of Bartholomew

Just humour me here and let’s keep the name.  So what’s life like for Bartholomew?  You won’t see it for yourself because Bartholomew lives deep in the ocean, far away from our eyes.

That peculiar body serves a purpose, letting Bartholomew sort of float above the sea floor.  Instead of using a bunch of energy to move, Bartholomew keeps movement easy and light.

How big is this body?  A blobfish usually grows to approximately 12 inches (30 centimeters).  In fact, I just picked up a comic book I will soon be reviewing here on the blog, and it’s about the same length as a blobfish.

A Floating Feeder

And boy oh boy, feeding is an interesting activity for the blobfish.  While you or I take an active role in eating – we open our mouths and put food inside – the blobfish does it another way.  When Bartholomew feeds, it means just drifting along, swallowing food particles that float in its mouth.

Ugliness Comes In Many Forms

Bartholomew is yet another example of the consequences from overfishing.  Without adequate regulations around deep sea trawling, our ‘hello’ to Bartholomew may soon be a ‘goodbye’ instead.  While his appearance may be ugly, some might say that the actions of humans are far uglier.

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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7 comments

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!

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