Grex (biology)

Before they get stimulated to crowd together to form a grex, the amoebae simply wander as independent cells grazing on bacteria and other suitable food items.

According to species and circumstances, details of the shape of the grex and how it may form will vary but typically the stressed amoebae first produce pheromones that stimulate the flock to vertically assemble in a column.

When the column of aggregated cells becomes too high and narrow to stay upright, it topples and becomes a slug-shaped mass: the grex.

Cells forming the structural items, such as the stalk and shell, desiccate and die; only the spores in the fruiting body survive to propagate.

The spores then may be transported by media such as wind or water; they then may cover distances far greater than any that they could have achieved in their amoeboid form, and over regions where amoebae could not travel at all, such as dry surfaces.