Tuesday, July 29, 2008

panhandle lichen


Lichen is awesome.

Lichen (pictured above) is actually two organisms living in a symbiotic relationship. Fungus makes the body we can see and bears the name of the lichen, while the microscopic algal partner lives in the tissue of its fungal host. Fungi can't photosynthesize (they seem plant-like but are actually in an entirely different kingdom and are more closely related to you than plants are), they're heterotrophs that decompose organic matter to eat. The alga uses its host for the capture of water and minerals. The fungus benefits from the alga's ability to photosynthesize. The algal and fungal partners of some lichen have been separated and cultured in the lab, but out in the world, both rely on each other to grow and reproduce.

Lichen can survive in some pretty harsh natural conditions (many can enter a state of cryptobiosis-a sort of suspended animation-in response to dessication) but some are incredibly sensitive to man-made pollutants, and are widely used as pollution indicators.

Wednesday, July 23, 2008

Presidio Bee Walk

Did you know that there are over 60 species of bees living in the Presidio? Come meet some of your lovely native neighbors this Sunday with Dr. John Hafernik, entomologist extrordinare, from San Francisco State University. We have some truly beautiful native bees here in San Francisco-I would encourage everyone to make their acquaintance.

Friday, July 18, 2008

Scarlet Pimpernel

Scarlet Pimpernel (Anagallis arvensis)

Also known as "the Poor Man's Weatherglass" because the flowers only open when the sun shines (though you could probably tell when the sun was shining just by looking at the sky and not the ground). They'll close when it's getting dark, or when the barometric pressure is dropping, indicating a coming storm.
This plant is originally from Europe, but is pretty common in San Francisco. I guess it's considered a weed by lots of folks. I think it's lovely.


Monday, July 7, 2008

you are your own wilderness

You don't even have to get up to find wildness. Yes you, sitting there in front of your computer screen, are your own amazingly diverse ecosystem. The going estimate is that 500 to 100,000 species of bacteria can be found on the human body. The total number of microbial cells found on your body may exceed the number of your own personal cells by a factor of ten-to-one. That means if someone broke you down into a big old pile of cells only 10% of that pile would be you!

The diversity on your body is truly amazing-and vastly underappreciated. A recent study looking at the microbial diversity on human forearms (the part of your arm between your wrist and elbow) found 182 species, 14 of which had never been described. A normal human gut has at least at least 500 bacterial species, probably more. While your personal flora can make your armpits smelly, they are also the critters to thank for your ability to synthesize vitamin K and digest carbohydrates.

People are so freaky now about using crazy antibacterial, kill-everything soaps and sprays, which may help get rid of some of the cooties we're trying to avoid (at least in the short term, though it's also producing some gnarly super-bugs too), but we're also killing parts of the complex ecosystems that are our bodies before we have any idea what's there or what it does. Next time you eat a piece of bread, or get a little stinky after some hard work, give a little thank you to the marvelous critters of your body and the wondrous diversity that is you.

Human Microbiome Project at the NIH
Human Microbiome Project article in Nature