Friday, May 31, 2013

Snake Skin ... Patterns

Snakes are hunters - but they have natural enemies, too. Birds, raccoons, foxes and coyotes see snakes as tasty fast food. Sometimes the patterns on a snake's skin look vivid to us, but in their natural habitat those rings and blotches blend into the background. Designs can help break up the snake's outline.

Test it: Cut out a dozen snake shapes from cardboard. Then, using a field guide, color your snakes to match some of the patterns of snakes in nature.

Now head out to do some field research. Take your cardboard snakes to a wooded area and scatter them around. Challenge your friends to find the snakes - and write down (on the back of the snakes) which order they were found (first, second....). Then go to a different habitat, like a grassy area or a rocky area. Scatter your snakes around and see which ones are found first.

Do some patterns work better than others? Why?
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Friday, May 24, 2013

Snakes Bask in the Sun for a Reason

creative commons license

 Snakes, like their reptile cousins, are "coldblooded." That doesn't mean they have cold blood - it means that they regulate their body temperature by using the energy of the environment around them.

When we get cold, our body starts to shiver and that shivering warms us up. When snakes need to warm up, they slither to a warm rock and bask in the sun. It's like when you get out of a cold swimming pool and lay down on warm cement - it warms you up. 

Scientists have a cool name for using the environment to regulate your body temperature: ectothermic. 

You can test the powers of basking by putting different materials out in the sun for awhile. Try a piece of aluminum foil, a white napkin, a dark napkin, a light colored rock, a dark rock, and other items. If you have a thermometer, you can check their temperatures after 5 minutes, 10 minutes.... an hour. How fast do different materials warm up? Does color make a difference? 

Once your items are warm, put them in the shade. How long does it take for them to cool down? Check out other science posts at STEM Friday.

Friday, May 17, 2013


by Christopher Cheng; illus by Mark Jackson
 32 pages; ages 5 - 8
Candlewick, 2013

"It's morning in the bush. Python stirs..." She is hungry, but first she slithers to a sunny rock to bask and warm up. That's because pythons, like all reptiles, are ectothermic.

'Ectothermic' is more than just another cool word to add to your vocabulary; it refers to animals that acquire heat from their environment - like a sun-warmed rock.

This is a great story of the daily life of a python - but not for the squeamish or faint of heart. Because after shedding her old itchy skin (molting), this python is off on a hunt. She strikes out for a bird - and we see her rows of needle-like teeth that, writes Christopher Cheng, are "perfect for grabbing, hooking and holding". The bird escapes; a rat is not so lucky. We see python wrap around and suffocate its prey. We watch the rat disappear, tail-last.

Python lays eggs and coils around them to keep them warm. But once they hatch, she doesn't stick around caring for her young. That's OK because the hatchlings are soon ready to start their own lives of watching, waiting, and catching their own meals.

Pythons live in Africa, Asia and Australia. While they aren't native to North America, there are pythons living in the southern regions of the US - particularly in Florida where Burmese pythons are eating local wildlife. People organize "python patrols" and hunt the invaders. Where did these exotic pythons come from? People releasing their pets.

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Friday, May 10, 2013

Snakes Alive!

Garter Snakes (Photo credit: Miles Frank, U.S. Fish and Wildlife Service)

The other day I was walking down my road and a garter snake slithered out of my way. It was sunning itself on the warm hardpacked oil & stone surface, grateful for warmth after what seems like a late-arriving spring.

I usually have a snake or three hiding in beneath the mulch in my garden, or warming themselves on a stone in the morning. Snakes are great garden workers: they kill pests without poisoning beneficial species, don't eat the plants, and they're usually shy.

Like other reptiles, snakes have scales instead of fur or feathers. Unlike their reptilian relatives, snakes don't have legs, though way back in evolutionary time their ancestors might have. At least that's what some research indicates.

Of the 3,000 or so species of snakes around the world, 17 live in my state of New York. The most common is the garter snake that I see in my garden and along the roads. But I also find Northern redbellies, black rat snakes (really long!), green snakes (aka "grass snakes") ans milk snakes.

This year, 2013, is the Year of the Snake. Get to know some of the snakes in your neighborhood. Where do they hide during the day? Where do they sun themselves? And do they have special sunning places that they return to day after day? Make a "snake map" of your yard.

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Friday, May 3, 2013

Surface Tension - on earth & in space

Water is strong. If you want to know just how strong, fill a small juice glass up to the brim. Now grab a pile of pennies - a hundred might be enough...
Slip a penny into the glass. Does the water spill? Probably not, because a penny isn't very big and doesn't displace much water.
How many pennies do you think it will take before the water starts to spill over the lip of the glass? Ten? Fifty? Somewhere in between? Something higher?
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Test out your answer by putting pennies into the cup one by one. At some point get your eyes level to the top of the glass and look at where the water is!

Water molecules hold onto each other tightly. It's called surface tension.

Now consider what happens in space. To help you out, Canadian astronaut Chris Hadfield. He shows what happens when he tried to wring out a soaking wet washcloth. Note: washclothes are packed like hockey pucks for their trip into space!