Category: Natural World

On Rabbit Digestion

Figure 1. Undigested fiber from rabbit fecal pellets.

One of my favorite things is when my students teach me something I didn’t know. One of those things is that rabbits eat their own poop.

Well not exactly. According to Dana Krempels, from the University of Miami, rabbit fecal pellets (poop) are different from the other type of droppings that lagomorphs actually eat, which are called cecotropes (Kempels, 2010; Rabbits: The Mystery of Poop). Cecotropes apparently have lots of helpful bacteria and nutrients. Rabbits that don’t get to eat them tend to suffer from malnutrition.

Figure 2. Rabbit fecal pellets, with one mostly dissected, in a standard petri dish.

Independent Research Project

For her Independent Research Project (IRP) this term, one of my students researched rabbits, and, as was required, tried to find them on our nature trail. She found indirect evidence. Small fecal pellets in the grassy area next to the trail’s exit, just where her research said they might be (which was quite nice). The pellets were brought inside, dissected, and examined under the microscope (see Figures 1 and 2).

The magnified image showed what appeared to be a partially masticated (chewed) piece of fiber, probably grass. This is where I was informed about the double eating called cecotrophy. My student hypothesized that this sample might be something that had not been fully digested and the rabbit would come back and eat it another time.

The Scientific Process

I really like the scientific process that went into this project, even though I’m not sure I agree with the final hypothesis. The project started with background research that yielded a plan for field observation. The field observation resulted in samples being collected and returned to the lab for analysis. The analysis produced some interesting, enigmatic results, which lead to a proposed hypothesis that integrated the observations based on the original background research.

The only things I would like to add to this type of IRP is to have students include a detailed scientific sketch, much like the sketches of the early botanists and naturalists. I really like how these drawings integrate acute observation and artistic interpretation.

Visuwords: a visual dictionary

The definition of parasite on Visuwords.

Visuwords is a great visual dictionary. It not only gives definitions, but shows the links between antonyms, synonyms and etymology.

I plugged in a few of the words from this cycle’s vocabulary lists (parasite, circumnavigate, host, viceroy etc.) and the results were quite neat.

Also, if you double click a word/node it expands to show you the things it’s connected to. This can lead to a quite complex diagram. It would have been great to use it for the word navigator, because it gives a graphic organizer that pretty much covers what we talked about for social world this cycle.

Definition of eukaryote. Notice it links to the word prokaryote (the red line indicates that it's an antonym).

Insects with solar cells

The yellow stripe on the oriental hornet's abdomen may act as a solar cell. (Photo by MattiPaavola via Wikimedia Commons).

We’ve seen that autotrophs get their energy from sunlight or chemical reactions, while heterotrophs get their energy from eating other organisms. We’ve also seen that some protists, called mixotrophs, can do both.

We have not yet discussed reptiles, which are heterotrophs (as are all members of the Domain Animalia), but use the sun to regulate their internal temperature (they’re ectotherms).

According to a recent article, the yellow pigment on the oriental hornet’s belly can convert sunlight to electricity, and is believed to have some role in photosynthesis in some plants.

The researchers used the pigment to make their own solar cell, but it proved to be quite inefficient, only converting 0.335% of the incoming light to electricity. However, the microscopic ridges on the hornet, and the layering of the insect’s cuticle, suggest that the hornet itself is more efficient.

I’m not quite sure how the hornets would use the electricity if that’s what they’re doing, but they are more active in sunlight than in the dark, so some type of “solar harvesting” is probably going on.

Water for life; for civilization

The Nile and its delta (image from NASA).

This nighttime photograph of the Nile River and its delta from the International Space Station beautifully illustrate the importance of water for life and civilization. The city of Cairo is at the neck of the delta; the brighter spot where the distributaries diverge.

Spaceflight Now has other really cool photos. Bad Astronomy has an interesting post on the logistics of this particular photo, while Heather Pringle has a very interesting post on how the desert may have aided the ancient Egyptian’s civilization.

Exploring Space: Extrasolar planets

Notice the planet in the lower right corner? (Image from the Hubble Space Telescope via Wikipedia).

One of the neatest developments in recent space exploration has been the accelerating discovery of planets orbiting other stars. Other stars are just so far away that it’s insanely difficult to see anything orbiting them. Also, the stars can be much brighter, a billion times even, than the planets. So, in the beginning, they could just identify the largest of planets, Jupiter sized and bigger, because of they way they make their stars wobble, but this and other techniques have gotten better and better and now we’re looking at smaller and smaller planets, getting down to Earth sized objects.

Methods for detecting planets orbing other stars. Image by M. Perryman.

One of my students, in investigating modern space exploration, found The Extrasolar Planets Encyclopaedia, which is pretty sweet because it keeps a running tally of planets found outside our solar system. When he found it last week the number was 502, now it’s 504. The site also has a long list of the ground and space based projects looking for extrasolar planets, which demonstrates how active the field is today.

God, Glory and GOLD: but why gold?

Gold coin of Kumaragupta I. (Image from Wikimedia Commons).

NPR’s Planet Money has a nice story on why gold is used for money. They take the entire periodic table of elements and eliminate the ones that don’t work because they’re too reactive, a gas, too common, or too toxic. You’re left with five precious metals, rhodium, palladium, silver, platinum and gold, but only one of them has a low enough melting temperature so that it can be worked easily and is not ridiculously rare.

Also, Tony Clayton has a wonderful webpage on Metals Used in Coins and Medals. It has some fascinating details about the history of these metals and their alloys in coinage. For example, “In Old English the Latin word aes was rendered as brass, thus the use of the word brass to mean money still found today, especially in Northern England. “

Pumpkin Chuckin

Photo by <a href='http://en.wikipedia.org/wiki/File:Pumpkin_chucked_from_trebuchet_in_ohio.jpg'>Kevin D. Hartnell</a>.
Photo by Kevin D. Hartnell.

Mr. B’s put me on to the World Championship Punkin Chunkin Association, which has an annual competition. There’s a Discovery Channel program about it too.

Although my head-of-school is not partial to us throwing food around, a trebuchet would make a great project for physical sciences next year (Year B).

Microwave Science

Last year, for an IRP, one of my students did the experiment measuring the speed of light (and the wavelength of the waves) using marshmellows in a microwave. The video above (via Gizmodo) shows the pattern of the microwaves using some neon lights embedded in plastic. The video below, from MythBusters, shows superheated water in action; something I demo every time I make tea-water in the microwave.