The Fox's Animal Magnetism

For a while now, it has been thought that birds could see the magnetic field, in order to help them migrate.  It has been hypothesized that, when they are facing north, they can see a little blurry patch at the bottom of their eye.  If they are facing east or west, then they can't see the patch, so they know where to put the patch in their field of vision to get where they want to go.  Recent research by a Czech team of scientists seems to indicate that the red fox can also use the magnetic field, but for a different purpose: hunting.

The red fox (Vulpes vulpes) ("Least Concern" by the IUCN) has the largest geographical distribution of any member of the Carnivora, with habitat on all of the continents except for South America and Antarctica.  In North America, it inhabits the United States and Canada, in Europe and Asia it lives almost everywhere, and in Africa it lives in Morocco, Algeria, Tunisia, Egypt, Sudan, and Libya.  Not only does it possesses the range shown in the map below, it has been introduced to Australia, where, like the Dingo, it poses a threat to native species.

The red fox hunts by leaping up into the air, and coming down right on top of its prey, literally (for the prey, at least) appearing out of nowhere.  But how to pinpoint its jump?  The answer lies in the magnetic field, which is visible to the foxes.  But how does this work?  Out of all of the explanations set forth by various journals and such, I thought the explanation from Nature was easiest to understand.  Here's what they have to say:

"Think of a laser pointer attached to you that always points slightly downwards in the same direction. Now think of some object on the ground. If you walk towards the object until the laser spot is on top of it you know that object is a set distance away."

Generally, it was thought that foxes would pinpoint their location solely using their very acute sense of hearing.  But then the Czech team found that, when the red fox was leaping in a northerly direction, 74% of the attacks were successful, while the leaping attacks in other directions had the success rate of a mere 18%.  That's a very big difference, and seems to point to the magnetic field theory.

A picture of the red fox outside of the house that our friends the Beckleys rented in Breckenridge one summer.  Awesome place to stay, especially if you are looking to escape the summer heat!  Photo Credit: Julie Neher

East Breckenridge on Dwellable

Masiakasaurus knopfleri, and Other Interestingly Named Creatures

A few months ago, while reading Dr. Scott Sampson's book Dinosaur Odyssey (you probably know him as the guy from Dinosaur Train), he has a very brief section of his book where he talks about some interesting scientific names of sometimes not that interesting of creatures.  He presents nine of them, and here I present them to you, as well.

1.  Masiakasaurus knopfleri
This dinosaur, from Late Cretaceous Madagascar, was named by Scott Sampson and his colleagues, means the "vicious lizard of Knopfler," meaning Mark Knopfler, a famous musician.

 2.  Milesdavis zlichovianus
This trilobite was named after the famous jazz musician Miles Davis.

3.  Mozartella beethoveni
This wasp was named after two famous classical musicians, Wolfgang Amadeus Mozart and Ludwig van Beethoven.

4.  Dicrotenipes thanatogratus
This one is probably less obvious to most of you out there, but in Greek, thanatos means "dead" (think Thanos, the villain for the next "Avengers" movie from Marvel: he loves and worships death), and in Latin, gratus means "grateful."  This midge was named after the famous band, Grateful Dead.

5.  Montypythonoides riversleighensis
This extinct Australian snake was named after the Monty Python franchise, but unfortunately, the name is now outdated; its correct scientific name now is Morelia riversleighensis.

6.  Strigiphilus garylarsoni
Named after the famed cartoonist Gary Larson of The Far Side fame (watch for at least one post featuring him next week).  Besides having this owl louse named after him, also has had a beetle and a butterfly named in his honor. Regarding the owl louse, he said “I considered this an extreme honor. Besides, I knew no one was going to write and ask to name a new species of swan after me. You have to grab these opportunities when they come along.”

7.   Ninjemys oweni
"Owen's Ninja Turtle" is named after the famous group, the Teenage Mutant Ninja Turtles, and was found in Pleistocene-aged rocks in Queensland, Australia.

8.  Gozillus

http://www.csmonitor.com/Science/2012/0425/Mysterious-Godzillus-fossil-find-stumps-scientists

9.  Darthvaderum greensladeae
One of my personal favorites, this mite was named after the famous Darth Vader, from Star Wars.

The Function of Cheek Pouches

A possible ancestor of Diprotodon (the largest mammal known from anytime in Australia, as well as the largest known marsupial known from anywhere in the world, and a relative of the wombat), the skull of Euryzygoma dunense, another extinct, megafaunal, eight foot long, quadrupedal herbivorous marsupial, is quite interesting: it has two extended cheekbones.  This gives Euryzygoma the unusual mammalian property of its skull being wider than it is long.  Although to most this probably doesn’t actually seem all that exciting, the extended cheekbones have led to two interesting theories regarding their function in the living animal.  One we will look at in a few weeks (the week of August 3rd to be more precise), but the other one we will look at now.

The hypothesis came about when the skull of Euryzygoma was first described.  The scientists who first described Euryzygoma thought that the lateral extensions of the zygomatic arch resembled those seen in squirrels, gophers and various types of Old World Monkeys, like the macaque and the baboon. 

 In the living animals just described, these lateral extensions function as cheek pouches, which make it so that the animals that possess them can store food in them.  That is why you so often see a squirrel running around with its cheeks puffed out.   

Some scientists think that Euryzygoma might have used its cheek pouches to store water; thus, it would not need to spend so much time near waterholes that were most likely infested with large crocodiles.  This would also help Euryzygoma travel longer distances during a drought, enabling it to move greater distances to reach waterholes that other animals would simply unable to reach, having a much more limited range.

Animal Spotlight: The Mountain Pygmy Possum

You've probably never heard of the mountain pygmy possum (Burramys parvus); few people have, it being one of Australia's many lesser known marsupials.  One of five extant (opposite of extinct, or still living today) species of pygmy possum, the mountain pygmy possum has a very interesting story about its discovery, a story that we will now look at.

The genus Burramys, the genus the mountain pygmy possum is a part of, also contains three extinct species of possum.   In fact, prior to 1966, the mountain pygmy possum had been described solely from fossils dated from the Pleistocene Epoch.  (The Pleistocene Epoch dates from around 2.5 million years ago to around 10,000 years ago, when the last Ice Age ended.)  It was first described from these Pleistocene fossils by the famous geologist/zoologist/paleontologist Robert Broom in the year 1896, and was assumed to be extinct, just like the other three members of the genus Burramys.  That is until 1966, when one showed up in a ski hut on Mount Hotham, a mountain in New South Wales, southern Australia, and home to the Hotham Alpine Resort.

Since this surprising discovery, scientists have located three populations of the Mountain Pygmy Possum in different spots in southern Australia.  Although it is exciting to discover a species that was previously thought to be extinct, it is saddening to find out that this animal has a wild population of a mere 2,000 individuals, and is labeled "Critically Endangered" by the IUCN.  Means have been taken to protect the mountain pygmy possum, including the so-called "Tunnel of Love," a little possum-path that granted the males better access to the female habitat, and helping to reduce fatal encounters with automobiles.

Works Cited:

Mountain Pygmy Possum. (n.d.). - Just another global2.vic.edu.au weblog. Retrieved June 29, 2012, from http://teacherrsc.global2.vic.edu.au/

Dinner Plain on Dwellable

Digest This: Or Can You? A Koala Could

I've been reading some interesting things about the koala (Phascolarctos cinereus) that I thought you might be interested in hearing.  As we all know, koalas are one of the sleepiest animals, and can be found sleeping and resting around eighteen or nineteen hours a day.  That means that out of their thirteen year life span, they are sleeping for around ten of those years. By comparison, a human with a lifespan of seventy-five years that sleeps an average of eight hours a day would sleep around 25 years of their life.  While a lot more than twelve years for the koala, keep in mind that humans only sleep around 33% of their life, while koalas sleep around a whopping 75-80%. But why do they sleep so much? The answer lies in what they eat: Eucalyptus leaves.

The leaves of the Eucalyptus trees are incredibly hard to digest.  Not only are the leaves very fibrous, much like celery (think about how hard celery is to chew), but they are also chock-full of toxins that very few animals can digest, with especially high concentrations of volatile oils and phenolic compounds.  What does that mean in English?  Well, phenolics are a type of organic chemical that naturally occur in plants, where they can act as deterrents against predatory browsing at the hands (or rather the mouths) of herbivores.  As stated before, the concentration of phenolics in the Eucalyptus leaves are so high that most animals would simply be unable to digest the leaves.  The koala decided not to take this lying down (ironic, as that is most of what koalas do in a day), and have evolved in a few key ways to help them deal with these toxins.

A fascinating moment of a koala's life: being awake.  Quite the statistical anomaly.

The first is simple; they have teeth that are great for chewing.  The broad, high-cusped molars possessed by the koala help it to thoroughly mash the food in its mouth prior to further digestion.  In our own mouth, we also have molars, along with a wide assortment of other types of teeth. When you are chewing your dinner, you tear bite-sized chunks off with your front teeth, or incisors and canines. Then, you move the food to the back of your mouth for further processing, and you further chew the food with your molars. The cusps on our teeth make it so the food is crushed fairly thoroughly. However, the koala doesn’t eat food like lettuce that can be torn up fairly easily. Thus, the koala has higher cusps on their molars, allowing for the Eucalyptus leaves to be ground up quite nicely.

A koala skeleton on display at the American Museum of Natural History in New York, New York.  Note the molars in the back.

The second major evolutionary adaptation is that the koala has a very long cecum, a pouch of sorts that is considered to be the first part of the large intestine.  In fact, at four times its own body length, the cecum of the koala is proportionally longer than that of any other mammal on the planet! The bacteria in the cecum help to break down the tough tissues in plants, such as cellulose, an important structural component of the cell wall in plants.  This gives our fuzzy marsupial friend a whole lot more time and space for that tough plant material to be digested.  Apparently, it takes a whole lot of guts to be a koala.

Believe it or not, I don't have a picture of a koala cecum on file.  So instead, take a look at this other interesting adaptation of the koala.  Instead of having a single thumb like we humans have, it has two!  Its first two digits are both functional thumbs, and are opposable to the other three digits on their hand.  You can see part of the hand skeleton the picture above this one.

Koalas aren't born with those important cecum bacteria, though, and to my knowledge no animals really are.  After five months of suckling from mom, the koala joey starts to enjoy the "partially digested leaf material produced from the female's anus" (MacDonald, 1984), or, as I like to call it, "Mom's Butt Leaves."  This delicious meal is actually thought to come from the cecum, giving the joey those essential bacteria and microbes, not to mention a delightful, pre-digested meal of Mom's Butt Leaves.  (Check out our other post about butt bacteria and eating poop HERE.)

Get yours at your local King Soopers today!

A fourth innovation of the koala is simply the exorbitant amount of time that the marsupial spends sleeping.  When you sleep, you are burning fewer calories than you would be if you were running around or hunting, or moving through a Eucalyptus tree browsing on its leaves.  Therefore, the more time the koala spends sleeping, the more energy it saves in exchange.  (The popular myth that the koala gets "stoned" by the Eucalyptus leaves is nothing more than that: a myth.)  The koala is able to delicately walk the line that we all desire to find: the maximum amount of sleep that one can get without dying.  It's truly a marvelous achievement, one which the koala handles with much grace and aplomb.

During the Pleistocene, there existed a larger species of koala, Phascolarctos stirtoni, a slightly larger koala than the modern species, P. cinereus.  Based on dentary measurements of both species from Price et. al., I came up with an approximate size increase of 1.4.  That is, take the length of a body part of P. cinereus, the modern koala, and multiple that value by 1.4, and you should get the approximate length of the same body part for the robust koala, P. stirtoni.  Not exactly the most precise method, but one that'll work for our purposes.  Below, you can see an approximate size comparison that I made of the two koalas, our modern species in gray and the extinct species in brown.

An approximate size comparison between the modern Phascolarctos cinereus (right) and the extinct P. stirtoni, with a can of Mom's Butt Leaves for scale.

More recently, scientists have realized that there is actually no evidence that does not support the idea that the hypothetical Laser-Eyed Koala (Phascolarctos oculaser) could have maybe possibly existed.  Scientists have been quoted as saying "We have never found it but that's not to say that who's to say that we aren't all koalas."  Below is the first unrefuted photographic evidence of the Laser-Eyed Koala in action.

That incredible, hands-on natural history museum in scenic Morrison, Colorado never stood a chance against that koala.  Fortunately, repairs to the facility should be completed on time for tomorrows 10:15 AM tour, which is included with your admission fee and well worth the time.  Talk about great free advertising, am I right?

Works Cited:

Hättenschwiler, S., & Vitousek, P. (2000). The role of polyphenols in terrestrial ecosystem nutrient cycling. Trends in Ecology & Evolution, 238-243.

Logan, M., & Sanson, G. (2002). The effect of tooth wear on the feeding behaviour of free-ranging koalas (Phascolarctos cinereus, Goldfuss). Journal of Zoology, 63-69.

Macdonald, D. (1984). The Encyclopedia of mammals. New York, NY: Facts on File.

Nagy, K., & Martin, R. (1985). Field Metabolic Rate, Water Flux, Food Consumption and Time Budget of Koalas, Phascolarctos Cinereus (Marsupialia: Phascolarctidae) in Victoria. Australian Journal of Zoology Aust. J. Zool., 655-655.

Piper, K. (2005). An early Pleistocene record of a giant koala (Phascolarctidae: Marsupialia) from western Victoria. Australian Mammalogy Aust. Mammalogy, 221-221.

Price, G. (2008). Is the modern koala (Phascolarctos cinereus) a derived dwarf of a Pleistocene giant? Implications for testing megafauna extinction hypotheses. Quaternary Science Reviews, 2516-2521.

Price, G., Zhao, J., Feng, Y., & Hocknull, S. (2009). New records of Plio-Pleistocene koalas from Australia: Palaeoecological and taxonomic implications. Records of the Australian Museum Rec. Aust. Mus., 39-48.