Category Archives: Education

Nictitating membrane in a sharpie

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If you’ve never been up close to a blinking bird, here’s a GIF that slows down the blink in a sharp-shinned hawk (Accipiter striatus). In addition to using the nictitating membrane to moisten their eye, birds of prey invoke them to protect their eyes from branches during a hunting approach and from prey that might fight back. Humans, sadly, don’t have them anymore, save a little bit of tissue called the plica semilunaris.

As an aside, there’s something rather unnerving about a science fiction movie in which a human is portrayed with functioning membranes. I wonder whether part of our reaction (or my reaction, if it’s just me) is that the membranes might signal the onset of aggressive behavior, where the aggressor is about to strike and wants full protection. I wonder whether animals with functioning nictitating membranes have such a perception. Wouldn’t surprise me.

Sharp-shinned hawk nictitating membrane

 

Distinguishing tobacco and tomato hornworm caterpillars

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I’ve always struggled to remember the difference between tobacco and tomato hornworm caterpillars so I came up with some mnemonics. Sharing in case it might help others who struggle.

Tobacco hornworm (Manduca sexta) caterpillars have stripes (seven of them), so remember that by thinking of Lucky Strike cigarettes (seven is a lucky number; stripes sort of rhymes with strikes). Plus the horn on a tobacco hornworm is usually red or red-tipped, like a cigarette. Tobacco hornworms also have black shadows on their stripes, and and tobacco gives you dark teeth and lungs.

Tomato hornworms (Manduca quinquemaculata) have eight chevrons (Vs), which you can remember by thinking of V8 juice, which is primarily tomato juice.

Here’s a graphic that summarizes the above:

Photographs of tobacco and tomato hornworm caterpillars

Here’s a larger photograph of a tobacco hornworm (7 stripes, red-tipped horn) covered with Cotesia congregata pupae.

Manduca sexta

It is not the strongest of the species that survives

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“It is not the strongest of the species that survives, nor the most intelligent, but the one most adaptable to change.”

It is not the strongest of the species that survives, nor the most intelligent, but the ones most adaptable to change Charles DarwinThis quotation is one of the most popular and misattributed phrases on the internet — most people think it’s something Charles Darwin wrote. He didn’t. It’s from Leon Megginson, a Louisiana professor of business management.

To encourage proper attribution, I thought I’d seed the internet with three images that give Dr Megginson his credit. The hope is that these images might eventually get included in Google search results when people are searching for pre-made slides that have the quote.

It is not the strongest species that surviveThe first version features a Galapagos marine iguana with its mouth open, as if it was saying something. It’s actually yawning, so use cautiously if you are a boring speaker.

The second slide is a photograph of Leon C. Megginson himself, looking confident in front of chalkboard.

The final image is a photograph of Charles Darwin, the man who clearly inspired Megginson.

It is not the strongest of the species that survivesAs proof of why we need to get the word out about the quote’s source, here’s a feed showing how all the recent usage on Twitter.:

Most of the tweets are from nutritionists, motivational speakers, and business management types.

By the way, the misattribution exists even among people who should know better. E.g., the quote is found on the wall of the Charles Darwin Foundation’s gift shop, and on the floor of the California Academy of Science.

If you need an actual quote from Darwin, there are hundreds of thousands to choose from. Just browse Darwin Online for all his books (~42 of them!), articles (~246), letters, and notebooks. There’s also the Darwin Correspondence Project.