cross between an animal and a fungus

[Guest guest]

Slime mould

Staff — June 18, 2005

http://www.libraryjournal.com/article/CA608908.html

TAKE a walk in the garden or woods in early summer or autumn and you

may come across something on the ground that looks suspiciously like

dog sick. It may be dog sick, but equally it could be a slime mould,

a strange cross between an animal and a fungus that feeds on dead

grass or leaves and thrives in the ground's moist warmth.

Why strange? Slime moulds are known as " social amoebas " but they

don't behave like any other single-celled creature. The moulds are

hard to classify because their life cycle is similar to a fungus's

(they reproduce via spores), but they share more genes with animals

than they do with, say, yeasts. We know about their animal genes

because we now have the complete genetic blueprint for Dictyostelium

discoideum, the most commonly studied slime mould (Nature, vol 435,

p 43).

And then there's the outlandish way a slime mould hunts its prey. It

moves about the damp soil as a single blob of protoplasm with many

nuclei, gobbling up bacteria and particles of organic matter and

growing through simple cell division. Then, as its growth outstrips

its food supply, the creature sends out a chemical signal to other

slime moulds, which gather together to form a multicellular super-

organism. Covered in slime and often as big as a human hand, it

crawls through the forest in search of food, reaching a top speed of

about a centimetre an hour. Then, when resources run low, it finds a

sunny spot to bask and transforms itself into a spore factory,

dispersing its cells on the wind to better hunting grounds.

If you think that's clever, consider this: slime moulds appear to

possess a basic intelligence. In 2000, researchers in Japan found

that a slime mould called Physarum polycephalum could navigate a

maze. They placed pieces of chopped-up slime mould in various

corners of a plastic maze with two openings where they left oat

flakes, a favourite food of slime moulds. The pieces of mould came

together to form a single organism, but instead of filling the maze

as the researchers had expected, the organism withdrew from dead

ends and formed a single tube spanning the shortest distance between

the two openings. " Clever and cunning " is how they described it.

How does an organism with no nervous system accomplish such a feat?

It may be related to the mould's rhythmic contracting and relaxing

when it forms into a tube, and the way these pulses vary when it

comes into contact with food. Beyond that, where these enigmatic

creatures get their computing power from is still pretty much a

mystery.

[Guest guest]

Sounds like it would make for a great horror movie.

--- In , " tigerpaw2c " <tigerpaw2C@n...>

wrote:

> Slime mould

> Staff — June 18, 2005

>

> http://www.libraryjournal.com/article/CA608908.html

>

>