Tuesday, September 14, 2004

Smelly critters, glowing critters and wise elders

Last night we were treated to an olfactory feast, sort of -- we had two skunks fighting outside our apartment. We're three floors up and the smell still woke me up. It's quite amazing that something that small can smell that bad ...

And, while we're on the topic of critters that do weird things, the Hawaiian bobtail squid is a pretty weird and amazing critter. It lives in symbiosis with luminescent bacteria and uses them as camouflage at night. It lives in shallow water, and so would be visible in moonlight, except for this nifty trick: it senses the amount of moonlight hitting it and adjusts the light it reflects from the bacteria living inside it such that it doesn't cast a shadow. And, since it has to feed the bacteria, which is a drain to do, it squirts them out in the morning, when it goes to sleep, and then re-ingests them in the evening, when it wakes up. The bacteria themselves are pretty amazing: they only glow if there are a lot of them, via a phenomenon called "quorum sensing". In quorum sensing, the bacteria actually "communicate" with each other and then, depending on their number, decide whether to take a particular action or not. Not only cuddly, light-emitting bacteria do this: cholera bacteria use this mechanism to sense when there are enough of them that they can probably overpower the immune system. If there are, they emit their toxin that causes the diarrhoea etc associated with cholera; if there aren't, they just chill out until there are enough of them. The innovative mechanisms Nature has come up with continue to surprise me [and will probably do so forever] ...

I learned all this today at one of the weekly seminars held by the Biology department. Not only was that seminar illuminating, it was also populated by "smart old dudes" -- there were a bunch of professors who must have been in their 70's and 80's sitting in the front row. They all had snow-white hair and proceeded to interrogate the seminar speaker after her presentation. I just found it a weird juxtaposition to have them sitting in the middle of a bunch of people in their 20's and 30's -- not something you see a lot, at least in the corporate world.


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