A Tribute to Scavengers and Decomposers

by Jan Thornhill

I visited a school a few days ago to talk about my books and, as usual, passed around the contents of my “museum-in-a-bag,” a collection of, among other things, skulls, dinosaur bones, desiccated insects, snake skins, feathers, and a mummified bat and two hummingbirds. The children are always very careful with my treasures, but that day my white-tailed deer skull finally snapped in half. I wasn’t exactly surprised, since this particular skull has been handled by at least 5,000 kids over the past few years. Besides, I can always glue it back together again. I’d like to save it, though, because, like many of the things in my bag, the deer skull has a story.

White-tailed deer skeleton (Jan Thornhill)

I found it, along with most of the rest of the deer’s skeleton behind a fence on my road. It’s not hard to imagine how the animal died: I’m sure someone struck it by accident with their car. Though mortally injured, it must have managed to make two great bounds, one to get off the road and the other to get over the fence. The person who hit it must have been relieved to see it disappear into the brush as he or she drove away. But then, alone, the deer collapsed and died.

A year earlier, I had looked for puffballs in exactly the same spot in late autumn. There were no deer remains then, so the longest it could have been hidden there was twelve months. Amazingly, other than a few wisps of hair and a couple of snippets of dried skin, the skeleton was completely clean – clean enough that I had no qualms about bringing it home.

So who do I have to thank for cleaning those bones for me? Scavengers and decomposers, that’s who – my favorite characters in the food chain.

I was quite sure a coyote must have visited the corpse of the deer shortly after it died since the bones of two of its legs were missing. The coyote is the only animal in my neighborhood that is strong enough to drag away such large parts. Though they’re predators, and often hunt for food, coyotes are also such frequent scavengers that they’ve developed a special receptor in their brains that makes them immediately throw up anything that is dangerously rotten. So a coyote wouldn’t have had to feed on the carcass immediately, especially if the deer had died in the cold of winter.

Coyote feeding on elk carcass (Courtesy Bryan Harry, U.S. Fish & Wildlife Service)

Turkey vulture

Other scavenging mammals, such as foxes and skunks, might also have visited the corpse, as well as birds, such as crows and vultures. Our local turkey vulture is one of the few large animals that is a dedicated scavenger, which means that its only food is carrion, or already dead or decaying flesh. They’re perfect for this job: they have an extremely well-developed sense of smell that allows them to home in on food that's miles away; their bald heads reduce the amount of rotting matter that might stick to them; strong acids in their digestive tracts destroy harmful bacteria; and their urine is also very acidic – and here’s the best part – so they pee down their legs to let the acid destroy nasty bacteria clinging to them. 

As well as being fed upon by these larger animals, in the warmer months corpses attract an amazing number of insects. A variety of flies are lured by the smell of death and lay their eggs. Their larvae, or maggots, are voracious carrion feeders. Flesh-eating beetle larvae continue the job and, later, other beetles with specialized mouth parts show up to feast on tough skin and ligaments, followed by moths that eat fur and hair. These insects all arrive at such specific stages of decomposition that forensic entomologists, scientists who study the insects that are found on or near dead things, can use their knowledge of this progression to determine the time of death when the remains of a human are found.

Close-up of a blowfly maggot (Eye of Science)

Throughout this whole process bacteria are active, gobbling up the corpse from within. These bacteria produce gases as a waste product, and it’s these gases that are responsible for the putrid odors that waft off rotting animals. Humans are naturally revolted by these smells, which is a good thing. If we weren’t disgusted by the smell of decomposition, we might be tempted to eat food that has gone bad and get sick from the bacteria growing on it. Interestingly, almost everyone in the world says the same thing when confronted by these smells, some version of “Yuck!” or “Ick!” This verbal gagging is so natural and so universal that some people think it might be the way that human language began.

My tip to anyone who finds an animal skull (or other bones) and wants to bring it home, is to use your eyes and nose. If it looks gross and smells disgusting, leave it where it is. Mark the location and return in a few months. More often than not, scavengers and decomposers will have completely cleaned it up for you.

You can find out lots more about death and decomposition in my book: I Found a Dead Bird: The Kids’ Guide to the Cycle of Life & Death (Maple Tree Press)

Here’s a fun, time-lapse video showing a watermelon decomposing over 35 days: http://thekidshouldseethis.com/post/12926682492

Clues in the Rocks

By Claire Eamer

“The role of a geologist is much like the role of a crime scene investigator,” says Joel Cubley, geology instructor at Yukon College in Whitehorse. Geologists try to figure out what happened long ago in Earth’s history from small, fragmentary clues, he explains. But what took place long ago was certainly not small.

Cubley’s specialty is tectonics, and that’s just about as big as it gets. It’s the study of the movements of the great plates that carry the continents slowly over the face of Earth, pushing up mountains and excavating oceans as they go.

Out there, beyond the east coast of Newfoundland,
the Atlantic Ocean is slowly getting wider.
Claire Eamer photo

Tectonics is a relatively new field. About a century ago, German scientist Alfred Wegener suggested that the continents move, but most geologists thought he was talking nonsense. It wasn’t until well into the 1950s that American scientists using sound waves to map the ocean floors found proof of Wegener’s theory. Marie Tharp, one of the few women working in geology at the time, spotted what looked like a rift valley on the floor of the North Atlantic Ocean. It turned out to be exactly that — a place where two parts of Earth’s crust are pulling apart, widening the ocean and pushing Europe and North America away from each other about as quickly as your fingernail grows.

Even that slow movement, over time, can create huge changes. On the west side of North America, tectonic movement has thrown up range after range of mountains between the eastern slopes of the Rockies and the Pacific Coast. Cubley is particularly interested in gap between a couple of those ranges, a place where two sections of crust have moved in a way that stretches the surface rock. It’s a 200-kilometre-wide zone of jumbled ridges and valleys called the Grand Forks Complex, lying roughly between Castlegar and Revelstoke in southern British Columbia and extending down into Washington State.

The snow-capped St. Elias Mountains, the highest
in Canada, were created by slow tectonic movement.
Claire Eamer photo

A feature of the Grand Forks Complex is occasional outcrops of metamorphic rocks, hundreds of millions of years older than the surrounding rock. How did they get there? That, in simple terms, was the subject of Cubley’s doctoral research.

“Metamorphic rocks are just rocks that have been cooked,” he says. Where Earth’s crust is pulling apart strongly enough to create a crack or fault, super-hot “cooked” rock can well up from far below the surface. Cubley suspected that the metamorphic rock in the Grand Forks Complex was evidence of a fault. But where?

In places like the Great Rift Valley in Africa, the fault is obvious – and huge. But the fault associated with the metamorphic rocks of the Grand Forks Complex would be much smaller and harder to spot. Cubley tackled the problem in the traditional geologist’s way, by sampling and mapping rocks on foot.

He spent several summers bushwhacking across the rough, wild landscape of south-central British Columbia, camping, hauling gear, and swatting bugs. When he finally found the fault, it was a bit of a let-down.

“It was a shallow ravine full of scrubby trees,” says Cubley. “That was kind of soul-destroying!”

But not for long. Cubley’s soul bounced back, and he’s well on his way to understanding how that modest ravine is linked to the unusual rocks of the Grand Forks Complex.

What he knows at this point is that the metamorphic rocks were formed at a depth of about 20 kilometres and a temperature of about 750 degrees C. Roughly 50 million years ago (almost yesterday in geologic terms), they welled all the way up to the surface and then cooled very quickly.

“I still can’t explain how they got to the surface that quickly,” Cubley says. But, with the help of a great deal of modern technology (and some more bushwhacking), he’s working on it.

What Makes an Octopus Blush - and How Exactly Do They Do It?

Posted by Helaine Becker

We've all heard about octopi that can change color to mimic their environment. But how do they do it? I discovered the answer when writing The Big Green Book of the Big Blue Sea for Kids Can Press.

The book is designed to present information to kids ages 8-12, but also to engage them with cool hands-on (or do we call that "experiential" now?) activities. Most people learn best by doing, and doing stuff that involves splashing water is pretty well a can't-fail learning opportunity.

The problem with octopi, though, was that I couldn't find a good activity anywhere out there to explain color-changing skin. I had to invent one.

Coming up with ideas is pretty easy for me. But coming up with ideas that any klutz, I mean kid, can do (And I am the klutz in question; if I can't do it successfully, it won't go in the book) wasn't a piece of cake. Luckily, cake was not required. Waxed paper and food coloring, however, were.

For all you lucky readers, here, in it's entirety, is the activity I invented. You'll find it, and many other fun and kooky things to try and do in The Big Green Book of the Big Blue Sea. Check it out, please!



 Seeing Spots?

Make your own octopus skin in less time than it takes an octopus to blush.

Image courtesy Pamsclipart.com

You Will Need

a large sheet of newspaper 

2 sheets of waxed paper about 30 cm (12 in.) square

yellow food coloring

1.     Lay the newspaper on your work surface to protect it.

2.     Lay down one sheet of waxed paper. Can you see the grayish newspaper through it? That’s the color of your octopus skin.

3.     Staying away from the edges of the waxed paper, carefully place 10–20 drops of food coloring on the waxed paper about 1 cm (½ in.) apart. Can you still see the gray newspaper between the colored dots?

4.     Hold the second sheet of waxed paper above the first sheet. Gently place it on top of the first sheet. See how the spots seem to spread out? Gently press on them with your thumb to spread them out even more. Can you still see the gray newspaper? Or does your octopus skin look yellow?

5.     Lift the top sheet of waxed paper off the bottom sheet. Do the dots return to their original size?

What’s Going On?

An octopus can change color to hide from prey or predators by blending into its surroundings. Many scientists think octopus also use color to communicate and express emotions, such as fear or dominance.

But how do our wriggly friends achieve this tint-o-riffic trick? Octopus skin contains microscopic pigment-filled structures called chromatophores, represented here by the dots of food coloring. Real chromatophores are so small, you can’t usually see them.

When an octopus wants to change its hue, it changes the size and shape of its chromatophores. Your thumb, forcing the dots to expand, acts like the small muscles in the octopus’s skin. They pull on the chromatophores to widen them. Now the skin they’re in is filled with color!

When the octopus relaxes, the chromatophores shrink back to their normal size. The octopus’s skin returns to its original color.*

*Excerpted from The Big Green Book of the Big Blue Sea, Copyright 2011 by Helaine Becker, Kids Can Press, Publisher. All rights reserved.

Math, Religion, and Chimpanzees

Photo credit: Aaron Logan

The farmhouse was old. The sixteen foot dining table we were seated at was too. This was a typical gathering with my in-laws, deeply committed Christians. It was during one such dinner that a someone said, "chimps share over 99% of our DNA because they were created by God to test our faith."

By this time, I`d just spent several years of graduate school in the same department as the famed atheist Richard Dawkins. When I passed by his office, I used to stop to read the latest hate mail taped to his door, presumably sent by Christians who believed damning Dawkins to Hell was the best way to help him avoid it. So, while it was a shock at first, I was getting used to the fact that a few of Earth`s modern citizens believe humans walked alongside dinosaurs.

In that Canadian dining room, face-to-face with similarly twisted logic, I realized the root of the "evolution vs. religion debate" is fear. The idea that humans came into being just like all the other beasts lovingly housed on the Ark threatens some Christians` identity in a way that is so terrifying they`ll do mental gymnastics to avoid it, and a few feel pushed to more aggressive defense tactics.

I was glad of this insight when, as a student at teacher`s college, I was charged with teaching evolution to a class of grade 12s in a public high school in a large Ontario city. The experienced science teacher whose class I was borrowing, whose job it was to mentor me, confessed that he'd had a difficult time with the subject, though he'd not succumbed to the temptation of reducing the unit to a brief overview delivered in as little time as possible, as had some of his colleagues. In the photocopying room on the first day, a fellow student teacher exclaimed above the whizzing, flashing 21st century technology, "you`re allowed to teach that?"

This was going to be harder than I thought.

First, I asked the students to indicate if they believed in evolution - anonymously. About half of them indicated so. Then, I taught my heart out, while trying to calm potential fears: I mentioned the polls of scientists, half of whom report belief in a Higher Power; the same stats as the rest of the population. I suggested belief in God is not reliant on science for proof or disproof; indeed it cannot be. I told them about Christians who study evolution, and I compared the issue of evolution in our society to the long since (largely) resolved issue of the Earth being round, not flat.

Three weeks later, I repeated my survey. A little more than half were convinced. From this I concluded:

1. The fear of evolution runs deep;
2. High school is much too late to teach evolution – students have already made up their minds based on only God-knows-what; and,
3. I had failed.

Recently, I’ve decided I might have been complicating the issue. Now, on the rare occasion that anyone asks, "what is evolution?" I say, "evolution is simply math." We have genes. Genes vary, so we`re all different. Any combination of genes that is more likely to survive and reproduce is… (Drum Roll)…more likely to survive and reproduce. I figure it is pretty hard to argue with that, though I`m sure someone will.

Alas, if only our ideas evolved as efficiently as our genes do.

What's NOT a black hole?

By M. E. Powell
(Photo - http://creativity103.com)

Scientists and science fiction writers often influence or inspire each other. I gained some insight into that process during "When Words Collide," the Calgary science fiction and genre writers festival, earlier this year.

For example,  David Wesley Hobill of the University of Calgary led a workshop in his special interest subjects: black holes, dark energy, and dark matter. I'm sure I'll over-simplify what he said, but his lecture shed some light on the "dark side of the universe" for me.

Hobill talked about finding black holes by observing gravitational effects. For example, we may observe a quasar at a far distance from Earth. If something is between us and the quasar, we know the gravity of that object will bend the light coming from the quasar. This "gravitational lensing" results in multiple images. If we observe light bending or being redirected around an object, but we can't see what is causing the light to bend, we deduce that a black hole is likely the cause.

Gravitational time delays caused by strong gravity may also cause time to slow down. Curved space requires more time to traverse. Inside it, a person's heartbeat may slow to two beats per hour, for instance, causing the person to live longer. Time would appear to stop. (You can imagine what science fiction writers might make of that train of thought!)

Hobill also debunked some popular science fiction myths about black holes. For example, he said, black holes are not:
- cosmic vacuum cleaners
- portals to another universe
- made of dense material.
In fact, black holes are completely empty space, he said, caught at the moment of a change of energy.

Instead, he pointed out, scientists would say that black holes are:
- formed from the gravitational collapse of a star 
- empty of space-time
- boundaries of causally separated regions
- cold and black
- and very very small.
If our sun collapsed into a black hole, for example, it would implode the gravitational forces, and it would become 400,000 times smaller. In other words, Hobill said, it would end up being about the size of downtown Calgary.

Here are some interesting links to follow up, if you're interested in black holes:
Hubble Site: Black Holes - Gravity's relentless pull: http://hubblesite.org/explore_astronomy/black_holes/
NASA: Black Holes - What are they? http://imagine.gsfc.nasa.gov/docs/science/know_l2/black_holes.html
NASA: What is a black hole? http://www.nasa.gov/audience/forstudents/k-4/stories/what-is-a-black-hole-k4.html 
Black Holes - Frequently asked questions: http://cosmology.berkeley.edu/Education/BHfaq.html

M. E Powell is the a Regina-based professional writer and the author of Dragonflies are Amazing (Scholastic Canada, 2007).