Tuesday, December 13, 2011
Saturday, November 19, 2011
Friday, November 11, 2011
Wednesday, November 9, 2011
Tuesday, October 18, 2011
Friday, October 14, 2011
Monday, October 3, 2011
Saturday, September 17, 2011
Thursday, September 15, 2011
I’ve had this image for a while but poor Catalpa just isn’t that interesting so it’s taken me a while to write about it. If you live in the
The tree can grow up to 30 meters but its crooked growth pattern limits its use for lumber cultivation. Apparently it was, at one point, used extensively for fence posts and, less successfully, for railroad ties. More commonly it’s grown ornamentally.
Another odd thing about the tree is that the leaves do not color in fall. Scientists, if my last research still holds up, still don’t fully understand autumn leaf colors (that is the natural history/physiology side of why it happens) so maybe someday this will be an more interesting fact. For now it’s an oddity to see a tree with green leaves into October or November that then suddenly depart to the ground.
Tuesday, September 13, 2011
Monday, August 29, 2011
Wednesday, August 17, 2011
Tuesday, August 16, 2011
Monday, August 15, 2011
Saturday, July 30, 2011
Saturday, July 16, 2011
Thursday, July 14, 2011
The Horseshoe Crab Diaries Part Four: In Which Paul Tries to Explain Why They Have So Many Legs to a Preschooler
So the other day I was at an academic summer camp talking with some preschoolers about my favorite animal and one of them asked me: "why does it have so many legs!?"
I know! Why does it need all those legs? Wouldn't six or even just four be enough? Probably it would be. This is more likely than not an example of randomness in the body plan of animals. Take humans as an example. Why do we have four limbs? Because our mammalian ancestors had four legs. Why did they have four legs? Because the lobed-fin fish that gave rise to land vertebrates had four fins that transitioned to limbs as they developed adaptations that allowed them to crawl out of the water. And why did the first lobed-fin fishes have four fins? Probably due to a random mutation in the hox genes (the genes that help to control embryonic development of bodies and limbs).
The same is true of a horseshoe crab: it has ten legs because...well because it's ancestors probably did. Or because there was a random mutation in the lineage's hox genes.
That's a pretty abstract concept even for an adult. So here's what I said: "They have a lot of legs because the group of animals they belong to has a lot of legs. Crabs, insects, spiders, they all have lots of legs and so do horseshoe crabs. That's really all I can say about it!"
I'm pretty sure my answer made no sense to the little guys. I know they can do similar and different but the concept of "relatedness" among different kinds of animals I think is a little out of reach. And like I said: it's frustrating that I've never been asked this question by an adult with the background knowledge and cognitive ability to understand the answer.
Any similar stories out there? What was your biggest success helping young children understand tough science concepts?
Tuesday, July 12, 2011
Saturday, July 2, 2011
11 different snails with 11 different patterns. Browns and yellows dominate the color variation in c. nemoralis but you can see oranges, tans, even one that was almost totally white. I wonder if there is some environmental factor but if so it must be quite acute since these are snails that were found in range of only several meters.