PETER D. MOORE
Department of Biosphere Sciences
Some plants, when perturbed by a grazing animal or by some sudden environmental stress, can transmit signals to other parts of the plant--or even to other plants--and induce in them a protective response. These can be thought of as "alarm systems." Oligosaccharides can act as signal compounds both in anti-herbivore and in anti-pathogen reactions.
M. Chessin, A.E. Zipf, "Alarm systems in higher plants," Botanical Review, 56, 193-235, July-September 1990. (University of Montana, Bozeman)
Some benthic algae appear to have very poor powers of spore dispersal in sea water, but the spores of one red alga, Iridaea laminarioides, can survive passage through the gut of an amphipod and can also be carried around attached to the limbs of these crustaceans. Such carriage can even permit the invasion of Iridaea beneath a canopy of other algae, such as Ulva.