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rain forest ant-spore neurobiology

L. Detweiler ld231782 at parry.lance.colostate.edu
Fri Sep 10 00:03:53 EST 1993


ura at strix.cluster.sub.org (Ulf Andrick) writes:
: D. dendriticum is a trematode (phylum plathelminthes), a `worm' with a
: complex life cycle. [...]

wow, you're saying this `worm' goes through not one, not two, but *three*
animal species in its cycle of propagation? can it propagate in a subcycle
or are all three elements (sheep/cow to snail to ant) required?

I'm quite positive that what I saw in the series was some kind of fungus
or spore -- they showed a picture of the fungus growing and budding out of
the carcass of the ant on the elevated location on the plant. I recall the 
narrator stating that `ants killed this way are quite commonly encountered'.

what is the approximate count of neurons in the ant? I understand the typical
ant has on the order of a few 100K neurons. It might be possible to argue
that the less complex the nervous system the easier it for some kind of
evolutionary parasite like D. dendriticum to evolve. In `accidentally' 
targeting some subregion a mutation would have fewer areas to `consider'
or `experiment with' so to speak. 

One wonders on the specific interaction with the nervous system. Likely,
it is simple such that the bacteria may mimic a neurotransmitter local
to a particular region, or maybe is toxic to some subset of neurons.
Is it `excitatory' in stimulating existing neurons or `inhibitory' in
`turning them off' or killing them? I'm generally making the assumption
that this mechanism is localized to at least some subregion in the ant.
I would wager that most `global' pathological effects on the nervous
system render it generally completely nonfunctional -- not useful for
the transportation of the worm-parasite.

Looking at D. dendriticum from an evolutionary perspective is rather 
puzzling as well. How could this parasite-worm develop? did it develop
from some other parasite that only involved the *two* animals, from one
that only involved *one*? to imagine that it just burst on the scene 
capabable, by some fantastic accident, of picking pecular `hooks' into
3 species is rather mind-boggling.

I also saw a special on ABC recently called `the hidden world' or something 
like that of an amazing fungus-spore-organism that appears in ordinary 
backyards.  the spores collect at one stage in life and actually migrate
in an oozelike fashion. Then they `bud' or `sprout' upon each other, with
lower ones drying up and hardening for others to advance upon. Then this
eventually `buds' into armlike projections that passing insects (the whole
thing is totally microscopic) brush off on, as I recall.

I wonder if there are any books on `bizarre life forms' -- all of this
is so unusual as to seem alien. They show how many of our categories -- 
`worms, parasites, virus, bacteria, plant, animal' etc. are not so
clear-cut as we would like to imagine. In fact the boundary between
life and non-life is increasingly blurred itself.

--

ld231782 at longs.LANCE.ColoState.EDU



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