They're not quite plant
or animal. But they're alive, beautiful and mysterious, and they do
amazingly sophisticated things without the benefit of brains or central
Many scientists believe slime molds are at least a billion years old, and they may have been important in the formation of soil on the earth "Can Answers to Evolution Be Found in Slime?", a New York Times story by Carl Zimmer,
tells a fascinating story of what researchers already know, and the
secrets they want to learn about this remarkable ancient life form.
Slime molds come in a dazzling array of shapes and colors, and they are
found in every climate on every continent. They communicate among
themselves, make decisions, and coordinate their survival activities
without central direction. They perform tasks that would seem to require
a researcher at the University of West England, showed slime mold can
replicate a highway system designed by humans. He put the mold in a
middle of a map of Spain and Africa, with food where various cities are
located, and saw the mold grow a network of tentacles almost identical
to the network of highways on the Iberian Peninsula. A Science Magazine
story reports how researchers showed experimentally that slime molds
reproduced an efficient network similar to the Tokyo rail system.
Adamatzky has used slime mold network building capacity to simulate
nuclear disaster, and taken inspiration from slime mold behavior to design software, and make electronic music.
Princeton Biologist John Tyler Bonner studied slime molds for years,
growing the cellular slime mold Dictyostelium in his lab, and studied
the way the mold, actually a huge community of separate amoebas, come
together for their common survival, and sacrifice themselves for the
greater good. When the organisms need food, thousands gather to form a
single blob that moves through soil and heads toward light. At the soil
surface, the blob transforms again, with some cells creating a cellulose
stalk, while others use the stalk to climb to the top and form a sticky
ball of spores. Those at the top survive, but those forming the stalk
die. Other members of the amoeba community ingest pathogens inside the
blob, and die of infections, so the surviving community stays healthy. Watch Bonner's YouTube video
How do amoebas decide which will live or die? That's not clear, but
Zimmer's story notes that amoebas that form slugs are relatives, so they
are helping pass on the genes of their community. How do they tell kin
from strangers? Researchers from Baylor College of Medicine recently
found they have chemical ways of doing that.
Biology Professor Steven Stephenson is one of 100 scholars in a slime mold initiative, funded by the National Science Foundation, at the University of Arkansas. Slime molds
break down plants and animals that die, devour such microorganisms as
bacteria, yeasts and algae and release nutrient that other organisms
eat. "If you removed those slime molds, the whole earth's ecosystem
would be very different," Stephenson told The Times. He and
colleagues will study where the organisms occur, how they are
distributed and how move around the planet, how may varieties there are,
whether various molds can share genes. Scientists believe greater
understanding of slime molds will offer clues on how life evolved, as
well as opening doors to new biological and medical knowledge.
Don't miss The Times slide show, Beauty and the Blob.
images from Beautiful Slime Mold and Slime Mold.