(^) The question that rarefaction curves suggested to Sanders (1968), and which
continues to fascinate others (Rex & Etter 2010), is: how can such a homogeneous
environment with so few apparent ecological roles retain so many species?
Presumably a benthont can: (i) ingest sediment; (ii) filter particulates from the water
above; (iii) wait for and move to deadfalls; or (iv) eat other benthonts. This scheme is
surely close to the total possible list, especially for infauna. The reason that the
question seems important is the “competitive exclusion principle”, previously
considered when we were puzzling over the high plankton diversity in subtropical
gyres. To repeat, it is a sort of ecological “law” derived from a theoretical model and
from experiments in jars with paired species of flour beetles or Daphnia: interactions
between species populations competing for limited resources are expected to result
eventually in one winner, losers becoming extinct. If that’s true, and there are very
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