planktonic polychaete, could have many more arrows, eating virtually any smaller
plankter passing by. Adult herring almost certainly eat larval herring when they
encounter them, just as they eat sand lance (Ammodytes) juveniles. Moreover, herring
are not the top of the food web with which they interact, but are eaten by cod, hake,
small sharks, tuna, harbor porpoises, seals, and seabirds, among a longer list.
Fig. 9.1 Alister Hardy’s (1924) classic pelagic food-web diagram from large
phytoplankton to herring. All of these links are accurate. Many of the predators of
herring (and trophic levels above those) were also known in 1924. Recent insights
introduce much more complexity at the primary production and herbivory levels.
(^) (After Hardy 1924.)
We are not done, yet, with even the complexity well known by Hardy in 1924. Each
of the metazoan elements of the food web has a development sequence from eggs to
∼1000-fold larger adults, with shifts in diet and predators as they grow. A copepod
nauplius is much the same size, eats the same diet, and dies in the mouths of the same
array of predators as a tintinnid protist. The entire dynamics of such skeins of
connections cannot be fully evaluated, but we have learned since Hardy’s work that
there are multiple food-web levels involving smaller organisms: autotrophic bacteria,
nanoplanktonic grazers, abundant herbivorous, and predatory protists. Organisms
release organic matter into solution directly and during feeding. It is taken up by
heterotrophic bacteria and returned to the particulate food web. Some of these