including histamine, a substance that our cells
use to signal each other in response to
damage; antihistamine drugs give some relief.
Shellfish and Ciguatera Poisonings Fish and
shellfish share the waters with many
thousands of animal and plant species, some
of which engage in nasty chemical warfare
with each other. At least 60 species of one-
celled algae called dinoflagellates produce
defensive toxins that also poison the human
digestive and nervous systems. Several of
these toxins can kill.
We don’t consume dinoflagellates directly,
but we do eat animals that eat them. Bivalve
filter feeders — mussels, clams, scallops,
oysters — concentrate algal toxins in their
gills and/or digestive organs, and then
transmit the poisons to other shellfish —
usually crabs and whelks — or to humans.
Accordingly, most dinoflagellate poisonings
are called “shellfish poisonings.” Many