What I Learned Today

After seven years of scooping kitty litter on a daily basis, one can’t help but meditate occasionally on the environmental impact of the stuff. What kind of litter is best? And what’s the best way to dispose of the scooped-out pet waste, or the used litter?

“Litter and the Environment” (2008) discusses the environmental impact of clay, silica, and plant-based litters. Did you know that the raw clay material (sodium bentonite) is obtained through strip mines, and that “The United States Geological Society estimates that 85 percent of the 2.54 million tons of clay used in this country every year is used for absorption of pet waste, with cat litter being the dominant”? That’s about 2.15 million tons of (ultimately) used-up clay that goes, most likely, into landfills. The article concludes that plant-based litters may cause the least environmental impact, but ultimately there is no perfect solution.

Some alternatives to clay-based litter that caught my eye, and have favorable comments in discussion fora, are:

• Feline Pine: litter made from pine wood. Some people really like it; some find the pine smell annoying. You can get a rebate for one bag of Feline Pine to try it out for free.
• Yesterday’s News: litter made from recycled paper
• Swheat Scoop: litter made from wheat. I tried this for a while but found it didn’t cover odors as well as the clay-based litter.

These are inevitably more expensive than clay-based litters, but might ease your environmental conscience. For the ultimate in cost savings (at the expense of time), you can make your own paper-based litter.

Once you select a litter, there’s still the question of how to dispose of it after it’s used. I scoop waste (pee clumps and feces) from the litter into a Litter Locker, which is super handy (and keeps odors down) but not only consumes plastic, it seals the waste for eternity and guarantees it’ll never break down. But you can’t compost it (temperatures don’t get high enough to break down feces), you shouldn’t flush it (can clog pipes, and there’s a small risk of infecting marine life with toxoplasmosis, although apparently VERY small risk if your cat lives indoors and doesn’t eat mice), and from what I’ve read, most sources regretfully recommend sending it to the landfill. Probably the best solution is to put it in a paper bag or something a little more likely to ultimately decompose (versus plastic), then put it out with your trash.

I change out the unused litter very rarely, like every few months. From browsing online, I learned that some people just let the box fill up with waste and then throw out the whole thing once a week, which must make them go through a ton of litter! Why why why?

Finally, no discussion of this issue would be complete without mentioning the alternative strategy of toilet-training your cat, which uses no litter and takes another chore off your hands. However, the small toxoplasmosis risk would still be present.

I’m considering trying out Feline Pine and/or Yesterday’s News, just to see how well they work (and whether my cat will use them!). And I may try to devise an alternative to the Litter Locker that avoids the use of plastic. Hmm.

I had no idea what a broad range of topics the field of “radio science” covers. I recently attended the National Radio Science Meeting in Boulder, CO, to talk with other researchers about the latest advances in radio astronomy data analysis (e.g., hunting for pulsars). Other topics in the multiple parallel sessions included lightning detection, antenna design, remote sensing of rain, “biophotonics”, “metamaterials”, space plasmas, and “telemetry for monitoring and biosensing”. Intrigued by some of the talk titles, I attended one of the latter sessions.

One goal of this field is to develop and test low-power, efficient radio communications for implantable medical devices (IMD). One envisioned application is for people in very rural areas who don’t have regular access to a doctor. Internal sensors could monitor blood pressure and various nutrient levels, then report them to an external base station they could visually check. As one presenter imagined, “Low potassium? Push a button and find out what you should eat for the next week!”

The devices are still under development, and in the initial work they’re focusing on the ability to monitor blood pressure. They aren’t yet up to human trials. Researchers from Texas A&M and Mississippi State University described how they’d started with rats. They showed pictures of the rat surgeries needed to implant the tiny antennas and then described the experiments, which aimed to evaluate whether the simulated response from the antennas was the same as what was observed when it propagated through rat muscle, fat, and skin. Unfortunately, the presenter noted, they’d been forced to euthanize all of the rats after the tests, because they hadn’t coated the antennas with a “biocompatible material” and therefore by animal testing rules they could not let the animals live. (It seems odd to me that this oversight would not have been caught during the protocol review process!) At any rate, the results showed a not very good match between the simulated response and what they actually got, which they attributed to differences between human skin (in the simulation) and rat skin (in reality).

As a side note, I kept wondering if these tests really qualified for the “in vivo” term the presenters applied, since the rats went to sleep for the surgery and (presumably) never woke up. The point at which they were euthanized was never specified. I started wondering whether live fat/muscle/skin tissue has different dielectric properties than dead tissue, which I assume it must, since circulating blood probably affects any signal propagation. This particular experiment seemed perfectly designed to test both cases. But I wasn’t quite up to asking this question after the talk.

The next presenter (from the same group) continued on to describe their subsequent experiments with larger animals (pigs). Pig skin apparently is a much better match to human skin (insert obligatory “white meat” joke here), and they got an excellent match with their simulation. In this case, they used a proper coating and the pigs were permitted to live. The presenter also commented on how very expensive these particular bred-for-experimentation pigs are (about $10,000 each), although I had to wonder whether one must purchase an entire pig to do a radio antenna transmission test, or whether one can give it back afterwards to be used for other experiments, or possibly time-share with other researchers. But again I wasn’t actually able to ask a question, being more sort of transfixed in a rather distasteful fascination and slightly nauseated by all of the graphic surgery images!

These talks didn’t spend much time on other important IMD constraints, like where power for the wireless transmitter comes from and how to dissipate the excess heat generated without cooking the animal (or human) internally. They noted that the devices had a 25 day lifetime if in continuous use, or 1.7 months if only transmitting periodically, so I’m guessing that limit was based on some nonrenewable power source being exhausted.

Overall, the envisioned future of such devices is certainly promising—and I was kind of disappointed to see how premature such investigations apparently are (if this represents the state of the art). I would also have liked to hear more about the kind of technology used for the sensors that collect the data to be sent by the antennas!

Today I attended a dog agility competition for the first time, tagging along with my friend Wendy. It was a beautiful sunny day (despite significant fire-induced haze along the mountains) and we drove out to Rancho Cucamonga to Chaffey College for the show. We found a grassy field surrounded by tents and umbrellas to provide shade for the dogs as they waited for their events. We took our seats and watched quietly as a voice said, “Go,” and the first dog and handler pair came out.

There were two courses: “standard” to the left and “jumpers” to the right. Unlike ballroom dance competitions, the dogs seemed to be grouped in descending order of advancement, so first the “excellent”, then the “open”, and then the “novice” dogs competed. The Standard course included a ring to jump through, several low jumps, weave poles, a tunnel, a seesaw, an A-frame (to climb up and then down), a table (on which the dog had to sit for 5 seconds), a dogwalk (raised platform with a ramp at either end), and a chute (like a tunnel but with one end collapsed so the dog has to escape blindly). It was particularly fascinating to watch the dogs traverse the weave poles, which are spaced closely enough that the larger dogs end up hopping with their back legs held together in a complicated slalom to make it through. Very impressive. The Jumpers course was all jumps, plus weave poles and two tunnels, and generally looked easier to my untrained eye, but the dogs seemed to find it more difficult. I also think they had to clear the jumps without touching the bars, while touching I think was permitted in the Standard course (it wasn’t always clear when and for what reason faults were being called). Ultimately I believe these runs were being judged based on time (rather than style, faults excepted), but the times and the final results were never announced, so this is surmise (plus wikipedia research — and of course corrections are welcome!).

It was fascinating to watch the interplay between dog and handler. Some had a degree of synchrony that seemed almost psychic, or as if the dog didn’t even need a handler. Others would be going along fine and then the dog would just break focus (often for no apparent reason), leaving the frustrated and/or embarrassed handler to dance around, calling instructions, until giving up and carrying the dog off the course. Some handlers had a calm clear voice and others shouted continuously, sounding angry (but apparently investing energy in the voice helps communicate a need for speed to the dog). Some dogs would randomly run in the wrong direction or off the course — mistakes that would leave you wincing in sympathy.

Overall, it looks like a great way to spend time with your dog (and get exercise with yourself), and from what I saw, the dogs in general were very well behaved both on and off the course.

What changes are needed to move from an aquatic existence to one on dry land? According to David Attenborough, a watertight skin, eggs with a hard shell, and stronger skeletal support to combat gravity. The differences between an amphibian’s egg and a tortoise’s egg also go more than shell deep: the embryo has to excrete waste, which in the water is naturally dispersed through the (permeable) egg membrane. On land, embryos instead develop an allantois (from the Greek word for “sausage”), which not only stores waste, but also permits the embryos to breathe. They need oxygen, and again in the water this would occur naturally through the membrane — but with a shell, that’s not possible. The allantois, however, presses against the shell strongly enough to exchange gas, and the embryo is connected to the allantois with blood vessels to treat it somewhat like a lung. Wow.

According to the wikipedia entry, human fetuses also have an allantois, which is inside the umbilical cord!

Darwin was first inspired about natural selection when observing the strikingly different tortoise shell shapes observed in the Galapagos Islands — distinct enough that a tortoise’s home island could be immediately inferred from its shell (well, or its taste):

The inhabitants, as I have said, state that they can distinguish the tortoises from the different islands; and that they differ not only in size, but in other characters. Captain Porter has described those from Charles and from the nearest island to it, namely, Hood Island, as having their shells in front thick and turned up like a Spanish saddle, whilst the tortoises from James Island are rounder, blacker, and have a better taste when cooked. — Charles Darwin, Journal of Researches, 1845, p. 394

Unfortunately, he didn’t record carefully enough which island each of his specimens came from, so on his return to England he instead used the less dramatic finch-beak example to illustrate his theory. He himself knew almost nothing about birds; his servant Covington collected the finches, and John Gould back in England identified and catalogued them. It’s useful to have smart, industrious friends (and servants)!

Tortoises live mostly on the land, while turtles live in the water. You can immediately see the differences; tortoises have short stumpy legs, for walking, while turtles have flipper/paddle limbs for swimming. It’s the turtles’ bad luck that they still have to struggle out of water up onto land to lay their eggs when they breed — no mean feat!

Attenborough’s book next has a chapter on crocodiles (lower teeth are visible when the mouth is closed) and alligators (lower teeth are invisible when the mouth is closed). Apparently their teeth are good for gripping prey, but not sharp enough to cut it into bites, so they rip by spinning their bodies around the (dead) prey, then have to rise up above the water to swallow the meat, because they “have no lips” to keep water out of their stomachs if they swallow. It’s amazing they ever get anything eaten.

Finally, crocodiles have very long courtship and mating processes, which often involve blowing bubbles at each other to indicate interest.

What a great book! Next up are the lizards, my favorite.

(Other things I learned from “Life in Cold Blood” by David Attenborough: Amphibians and their alien adaptations)

There is a female frog that swallows its eggs to protect them from predators until they mature. Once swallowed, the eggs secrete a substance that inhibits the production of hydrochloric acid in the frog’s stomach and halts normal muscular contraction that shifts food through the stomach and into the gut. Effectively, the frog’s digestive system turns off for six weeks for this “gastric pregnancy”. Not only that, the baby frogs get so big that they compress the female frog’s lungs, and for the last part of this experience she has to breathe through her skin instead. Imagine her relief when the frogs finally emerge from her mouth. (Photo by Mike Tyler)

This and other ultra-fascinating facts are to be found in David Attenborough’s book, “Life in Cold Blood.” I’ve only read the first chapter (on amphibians) so far, and literally every page has some interesting new fact on it. Not only that, but it is chock-full of gorgeous pictures of the animals being described. They’re all so interesting and alien that I’m nearly moved to get an aquarium and populate it for the observational opportunities.

Did you know?

• Some fish (e.g., lungfish) have primitive lungs (simple pouches lined with blood vessels) and can breathe air.
• The great crested newt lives out of the water, in damp regions, returning to the water to breed. Their eggs lack pigment to protect them from UV, so the female individually wraps each egg in a plant leaf with her hind legs (she lays 2-3 every day from March until mid-July! Talk about unending labor!).
• Many salamanders in the northeastern US have lost their lungs and breathe entirely through their skin, developing long tails that increase their surface area relative to their volume.
• Caecilians somewhat physically resemble earthworms, though they are amphibians. They burrow, and they’ve become sightless, although they do still have eyes — they’re just covered by skin. They are carnivorous, and in some species the female rears her young by repeatedly growing an outer skin, letting them nibble it off, and then resting and regrowing the skin. You can actually watch a video of this from the BBC’s Life in Cold Blood show. Wow, they’re tough! (Never go in against a Caecilian…)
• Different frog species may only be able to hear certain frequencies, which correspond to their own vocal range, so that they need not be confused by the cacophony of other species.
• The transformation from tadpole to frog is, really, simply miraculous. It is an herbivore as a tadpole, with a long coiled gut to permit digestion of plant matter. It grows front legs inside its gill chamber which then burst out fully formed on the sides, it develops lungs, its gut shortens and it becomes a carnivore. It basically completely reconfigures itself for an adult life in an alien environment, with alien food and a different means of mobility required.

I’m even more in awe, at the diversity and innovation of life on our one single planet, than I was before opening this book.