Owls in the suburban web of life

Out here in our neck of the Colorado Front Range, it’s been a good year for great horned owls.  Two owl families set up shop within a few minutes’ walk from home.  One was in a nest hole that’s been used in past years, but the one shown here used a new site in a broken tree top.  Dinner for the owlets included rabbits as well as snakes, voles, and doubtless other critters.

The owls draw quite a crowd at times, indeed often more than a half dozen people, along with their dogs, and cameras of various sizes. There were experts with huge lenses, who seemed like they were out there several times a day, and casual dog-walking (but also camera-toting) visitors like myself.  When a lot of people converged on the owl site, it got harder to get a good camera angle, but it became a festive occasion on its own account.

Great horned owls have been increasing in Colorado. I had certainly never seen so many of them until I moved here. Even outside the spring breeding season, there are a few times when I saw several adults just on a casual walk through the neighborhood. The other thing we have a lot of are rabbits. At times, it seems almost every lawn has a rabbit in full view; it’s like an all-you-can-eat rabbit bar. So, I have assumed that this partly explains the abundance of owls.  But according to the Colorado Breeding Bird Atlas, the increase of great horned owls in Colorado has coincided with a decline of the long-eared owl, likely due to competition.  So, not all the owl species are happy — despite the rabbit bar.

Osteoblast settles down and changes her last name

Many people these days are aware that their bones are in a constant state of flux, and that’s just one more reason to get some exercise — the mechanical stresses tell the cells in your bones to add more bone matrix (the nonliving material between the cells — mostly the hard mineral calcium phosphate, but also collagen and other ingredients).

There’s an important transition in the life of your bone cells. The early, “young and restless” cells that travel around and secrete bone matrix, sowing their wild oats, so to speak, and perhaps “having a blast”, are conveniently known as osteoblasts.   Gradually, most of the space gets filled in with hard matrix, and eventually the osteoblasts become trapped in their own secretions.  Once the cell is forced to settle down “on site” in this way, it is (again conveniently) known as an osteocyte.

The metaphor of “Mrs. Osteocyte” having “changed her last name” from “blast” to “cyte” was too perfect to resist, although I must point out that the metaphor relies on gender stereotypes that are rapidly becoming obsolete.

Anyway, Mrs. Osteocyte has plenty of work left to do and is not at all isolated, as it might seem. She maintains a firm grip on all her neighbors, sharing nutrients, wastes and chemical signals with them, directly through gap junctions. Indeed, osteocytes play an important role in detecting the mechanical forces that act on the bone, and secreting signals that direct the activity of osteoblasts. So, in effect the older generation still calls the shots!

 

Pangolins can’t wait 11 months

If you enjoy strange and whimsical-looking creatures, then pangolins are definitely for you. These tropical mammals look like something out of a kids’ cartoon fantasy, perhaps a cross between a dinosaur, and a fish out of water.  They have been one of my favorite animals since I first saw illustrations of them in books as a kid.  They are hard to find in zoos, perhaps because they specialize on ants and termites. During one of my visits to the San Diego Zoo some years ago, they kept a pangolin in the behind-the-scenes collection, but it was only brought out occasionally, and not during my visit. Finally, on a trip to Taiwan, to my great delight I found a pair of pangolins in a regular exhibit at the Taipei Zoo. There’s something about a bizarre beast like this that never seems real until you finally witness them going about their business, with your own eyes.  They were every bit as engaging as I could have imagined — exploring their surroundings with energy, playing with toys in the exhibit.

You may have already heard that pangolins are the world’s most trafficked animal.  So, we all need to celebrate these creatures, and make it known that we value them, before it is too late.  World Pangolin Day happens every February, but I don’t want to wait another 11 months to tell the world about them!

You can visit the Pangolin Blog at pangolins.org and cheer on (and donate to) the organizations that are working for pangolins.  And, you can get creative, as I have tried to do, and celebrate pangolins in your own way.

From pangolins.org —

12 things you can do to help pangolins on World Pangolin Day and beyond:

  1. TWEET using the hashtag #WorldPangolinDay
  2. LIKE the World Pangolin Day Facebook page
  3. BLOG about pangolins on World Pangolin Day
  4. SHARE pangolin information on your social media networks
  5. CREATE pangolin art — paint, draw, sculpt, tattoo
  6. EDUCATE by giving a presentation about pangolins at school
  7. SUPPORT organizations which are working to protect pangolins
  8. HOST a World Pangolin Day party or event (post your photos on the World Pangolin Day page!)
  9. BAKE cookies or a cake in the shape of a pangolin (post your photos on the World Pangolin Day page!)
  10. REQUEST full enforcement of laws and penalties for smuggling pangolins (and other wildlife)
  11. INFORM traditional medicine prescribers that the use of pangolin scales is illegal (and there are no proven health benefits to consuming scales — they are made of keratin, just like fingernails!)
  12. NOTIFY the authorities if you see pangolins for sale at markets or on restaurant menus, or if you know of anyone capturing or possessing pangolins.

Pancreas adds the special sauce

Last time we looked at a gland in the stomach where acid and an enzyme are secreted to begin the breakdown of protein.  I talked about the chyme that is produced by the mixing of stomach secretions with the food. As chyme leaves the stomach (symbolized by the hamburger — although in reality it is now mush), it enters the duodenum (shown here as a pink tube) — the first part of the small intestine, and by far the shortest  (the original term “duodenum digitorum” meant it was “twelve fingers’ widths” in length).  It’s a tiny part of the 10-foot long small intestine, but a vital part, because this is where several key ingredients are added.

The pancreas is far more important for digestion than the stomach because it secretes enzymes to digest all three food groups — fats, carbohydrates, and proteins.  It’s a somewhat fish-shaped gland, that sits behind the stomach.  These enzymes don’t function well in an acid environment, so the pancreas throws in a little natural “alka-seltzer” (bicarbonate) to neutralize the acid, and all this is poured together into the duodenum, through a duct.

The word pancreas means “all flesh” because there is little in the pancreas other than soft, secretory cells (nothing tough, no gristle).  I tried it once in New Orleans (it’s called “sweetbread” on the dinner table), and it wasn’t bad at all.

A gutsy first post


This view of a gastric gland marks the first post in this blog about biological cartoons.  The goal of the blog is to share some of the cartoons I’ve been using in my classes, and meet up with like-minded folks who share my view — that most lectures and nonfiction books are better off with a few cartoons. I will also broaden the discussion at times to look at the whole genre of educational cartooning, and share with you some of the best examples I’ve found.

But my training is in biology, so that will be my main focus.  The choice of the gastric gland is perfect, not just because I will be lecturing on it tomorrow (really!), but it also represents the anxiety (and a little extra stomach acid) I have in launching this project. I have never done a blog before; it sounded like too much time commitment.  But as the cartooning has become central among my interests, I realized it was time to move beyond the powerpoint slides and reach out — I’m hoping at the very least, there are a handful of teachers out there who might find a place for these cartoons in their classroom.

Since space is not an issue here, what I will do is show the cartoons unlabeled, and provide explanatory text, with the main terms in bold.  The drawing shows the main cells of the stomach epithelium (orange) secreting mucus, which protects the epithelium from its own secretions. Nevertheless, there’s rapid turnover of cells (replaced every few days), and a couple hapless oldsters are shown plunging into the roiling cauldron of stomach acid and food, known as chyme. This fortunate term (which, happily, comes from the same Indo-European root as “humor”!) gives rise to a plethora of puns, one of which is posted on the “wall” next to the “police chief” cells representing chief cells.  These cells secrete pepsinogen, an enzyme precursor, which when activated (by acid) digests proteins in the stomach. So the police chief is truly “taking a bite out of chyme”, which is a reference to the “take a bite out of crime” ad campaign from the 80’s.

Stomach acid is secreted by parietal cells (blue), which are the most realistic drawings in the figure — their “teeth” are the many microvilli (convolutions of the membrane) that add surface area, maximizing the ability to secrete acid. At the bottom of the gland is an enteroendocrine cell (purple), a general term for the many epithelial cells of your gut that secrete hormones.  The cell is “tasting” the food molecules in the gland, and sending out a hormone into the bloodstream to activate other glands of the stomach. Finally, the pink cells with pacifiers are (you guessed it) baby cells, or stem cells, which have a sort of “immortality”, continuing to divide throughout your life, while their progeny migrate up and down to become the replacement cells in the epithelium.