Glacier Mice

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At first glance the surface of a glacier hardly seems hospitable. Cold, barren, and windswept, glaciers appear to be the antithesis of life. However, this assumption is completely completely false. Glaciers are home to an interesting ecosystem of their own, albeit on a smaller scale than we normally give attention to.

From pockets of water on the surface to literal lakes of water sealed away inside, glaciers are home to a myriad microbial life. On some glaciers the life even gets a bit larger. Glaciers are littered with debris. As dust and gravel accumulate on the surface of the ice, they begin to warm ever so slightly more than the frozen water around them. Because of this, they are readily colonized by mosses such as those in the genus Racomitrium.

The biggest challenge to moss colonizers is the fact that glaciers are constantly moving, which anymore today means shrinking. As such, these bits of debris, along with the mosses growing on them, do not sit still as they would in say a forest setting. Instead they roll around. As the moss grows it spreads across the surface of the rock while the ice rotates it around. This causes the moss to grow on top of itself, inevitably forming a ball-like structure affectionately referred to as a "glacier mouse."

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Because the moss stays ever so slightly warmer than its immediate surroundings, glacier mice soon find themselves teaming with life. Everything from worms to springtails and even a few water bears call glacier mice home. In a study recently published in Polar Biology, researcher Dr. Steve Coulson found "73 springtails, 200 tardigrades and 1,000 nematodes" thriving in just a single mouse!

The presence of such a diverse community living in these little moss balls brings up an important question - how do these animals find themselves in the glacier mice in the first place? After all, life just outside of the mouse is quite brutal. As it turns out, the answer to this can be chalked up to how the mice form in the first place. As they blow and roll around the the surface of the glacier, they will often bump into one another and even collect in nooks and crannies together. It is believed that as this happens, the organisms living within migrate from mouse to mouse. The picture being painted here is that far from being a sterile environment, glaciers are proving to be yet another habitat where life prospers.

Photo Credit: [1] [2]

Further Reading: [1]

One Badass Moss

Badass and moss are two words that don't find themselves in the same sentence very often, if ever. Today I would like to introduce you to one moss that is certainly worth such a description. Meet Ceratodon purpureus, sometimes referred to as "fire moss." This lowly bryophyte is tough as nails and enjoys a global distribution because of it. From fires and heavy metal pollution to living in our most densely populated urban areas, this moss is a survivor. What's more, its ecology is absolutely fascinating.

Fire moss is truly cosmopolitan. It can be found on every continent and may only lose ground in the tropics where it is replaced by its close relatives. Though we often think of mosses as delicate denizens of shaded forest floors, fire moss is anything but. This is a disturbance-loving species. It gets the name fire moss for its habit of turning up in profusion following wildfires. Cleared of its competition, fire mosses growth can be quite explosive.

Being able to grow on a variety of substrates means that fire moss is equally at home in man-made habitats. It can be found growing in and along sidewalk cracks, old roofs, depressions in asphalt, and on wooden structures. What's more, it can tolerate pollution levels that would normally kill most mosses. One study found that moss grown on mine soils contaminated with toxic levels of heavy metals showed absolutely no decrease in fitness. In fact, they were indistinguishable from moss grown on clean soils.

This moss' lifecycle is ephemeral. Because it needs disturbance to persist, natural succession usually causes it to disappear from a site after a decade or two. Its spores, however, can remain viable for upwards of 16 years in the soil until fire, bulldozer, or any other large-scale disturbance opens the land again.

One of the strangest aspects of this fire moss is how it reproduces. Like all mosses, male gametophytes produce sperm that must make their way to the female gametophyte. They do this by swimming. Whereas moss species living in wet environments can let rain do the work of uniting the sex cells, fire moss has evolved a strategy more familiar to the flowering plants.

It was found that fire moss emits complex volatile scents. What's more, these scents are produced at different rates in the different sexes with females producing much more scent than males. It was found that microarthropods, specifically springtails, are attracted to these scents. Close investigation revealed that springtails significantly increased the fertilization rates in fire moss, hinting at quite a specific reproductive relationship between these organisms, both of which are representatives of some of the first organisms to ever make it onto land.

If this story has not convinced you that fire moss is one badass bryophyte I don't know what will. It is amazing to think that such an incredible organism is probably living out its life a stones throw away from where you are sitting right now.

Photo Credit: Ian Sutton (http://bit.ly/1LqqpMY)

Further Reading:
http://www.publish.csiro.au/?paper=BT9650303

http://www.nature.com/nature/journal/v489/n7416/full/nature11330.html

http://bit.ly/1U4lE2G

Zoophagous Liverworts?

Mention the word "liverwort" to most folks and you are going to get some funny looks. However, mention it to the right person and you will inevitably be drawn into a world of deep appreciation for this overlooked branch of the plant kingdom. The world of liverworts is best appreciated with a hand lens or microscope.

A complete lack of vascular tissue means this ancient lineage is often consigned to humid nooks and crannies. Look closely, however, and you are in for lots of surprises. For instance, did you know that there are liverworts that may be utilizing animal traps?

Right out of the gates I need to say that the most current research does not have this labelled as carnivorous behavior. Nonetheless, the presence of such derived morphological features in liverworts is quite sensational. These "traps" have been identified in at least two species of liverwort, Colura zoophaga, which is native to the highlands of Africa, and Pleurozia purpurea, which has a much wider distribution throughout the peatlands of the world.

The traps are incredibly small and likely derived from water storage organs. What is different about these traps is that they have a moveable lid that only opens inward. In the wild it is not uncommon to find these traps full of protozoans as well as other small microfauna. Researchers aimed to find out whether or not this is due to chance or if there is some active capture going on.

Using feeding experiments it was found that some protozoans are actually attracted to these plants. What's more these traps do indeed function in a similar way to the bladders of the known carnivorous genus Utricularia. Despite these observations, no digestive enzymes have been detected to date. For now researchers are suggesting that this is a form of "zoophagy" in which animals lured inside the traps die and are broken down by bacterial communities. In this way, these liverworts may be indirectly benefiting from the work of the bacteria.

This is not unheard of in the plant world. In fact, there are many species of pitcher plants that utilize similar methods of obtaining valuable nutrients. Certainly the lack of nutrients in the preferred habitats of these liverworts mean any supplement would be beneficial.

Photo Credits: Matt von Konrat Ph.D - Biblioteca Digital Mundial (eol.org), HESS ET AL. 2005 (http://www.bioone.org/doi/abs/10.1639/6), and Sebastian Hess (http://virtuelle.gefil.de/s-hess/forsch.html)

Further Reading:
http://www.bioone.org/doi/abs/10.1639/6