Mapping Species Distributions

NATURE NOTES

Slime mould, photo by Hugh Griffith

Return of the Blob

by Hugh Griffith

In an environment that is varying hues of brown and green, hot pink or coral red is hard to miss, so even the most preoccupied of hikers will stop agog having come across a slime mold, one of nature’s most mysterious creations.

The typical first reaction is to mutter, "What is this stuff?" The typical second reaction is to poke it with a stick.

Slime moulds are mysterious. They have been considered animals, protozoans, fungi or space aliens. Were they larger, they would come to life in cheesy 1950's sci-fi flicks.

They are usually classified within a group called the Myxomycetes. (Note that reading this column will greatly increase Scrabble scores.)

Slime moulds have several life stages. Perhaps the most interesting is the plasmodium, which is basically a single enormous cell with hundreds of nuclei.

Experiments have shown it can find its way through mazes to find food. More amazing, if chopped into pieces that are then returned to a previous maze, the plasmodial bits will reassemble and start to move, avoiding dead ends and heading directly back to the food again. Intelligent slime?

Slime moulds may appear in suburban gardens in colours other than bright red. It seems to be a relative of a species known as (I apologize for this) "the dog vomit slime mold," which is yellow, later turning to brown.

Apparently people blame neighbours' dogs for its appearance in their lawns and gardens, or rush their own pets to the vet for treatment after its discovery in the yard.

Species of this group ooze around as a plasmodium, travelling about a millimetre an hour. They feed on bacteria, spores and even other slime moulds until they run out of food.

They then find a warm spot and develop into a "fruiting body" up to the size of a small pizza called an aethalium, which is a mass of tightly packed spore-producing organs.

The aethalium shrinks and dries, and, in the case of our bright red species, blackens, which then alarms other hikers who think they have come across fresh bear droppings. It breaks apart and spores are spread by the wind or water. These hatch, move around in moist soil and fuse with others, eventually to form a new plasmodium.

More than a thousand species of slime moulds have been identified. They are not known to be harmful or beneficial to human interests, apart from the affront felt by some at having an uninvited giant amoeba meandering about their gardens.

By the way, this is an early appearance for a red blob slime mould. They are seen in our region every year, but typically this species forms aethalia when the hot weather hits in June or July. Is this another indicator of our strange, changing weather?

Forget woolly bear caterpillars as weather prognosticators. I'll stick with intelligent slime.

Hugh Griffith is a BC biologist and science writer.

Visit the E-Flora BC slime mold page.