### Identification Known as the "Silver of the Sea," *Clupea harengus* is a master of pelagic camouflage. Look for a sleek, fusiform (torpedo-shaped) body typically reaching 30–40 cm. They sport a brilliant deep-blue or greenish back that fades into shimmering, iridescent silver flanks and a white belly. A key field mark is the protruding lower jaw, which gives them a distinct "underbite." To distinguish them from similar species: unlike the Twaite Shad, herring lack dark spots along their sides, and unlike the Sprat, their belly scales are smooth to the touch rather than sharp and serrated.
### Habitat & Range These are the restless nomads of the North Atlantic. Their range is vast, stretching from the icy waters of the Arctic and the shores of Greenland down to the Bay of Biscay and the mid-Atlantic coast of the U.S. They are strictly pelagic, inhabiting the open water column over continental shelves. While they prefer offshore waters, they frequently venture into brackish estuaries and shallow coastal bays to spawn.
### Behaviour To witness a herring shoal is to see a single, pulsing organism. They are obligate schoolers; a single "mountain" of fish can contain billions of individuals. They follow a strict diel vertical migration, hovering in the safety of the dark depths during the day and rising to the surface at night to feed. An observer would notice their synchronized movements—a silver flash as the entire school turns in unison to evade a predator.
### Diet Herring are specialized "ram-feeders." They swim with their mouths agape, using gill rakers to strain tiny organisms from the water. Their diet consists almost exclusively of zooplankton, with a particular preference for fatty copepods and krill. During the summer "bloom," they gorge themselves to build the massive fat reserves required for winter survival.
### Fascinating Fact Herring communicate through "FRTs" (Fast Repetitive Ticks)—which are essentially high-frequency flatulence! By expelling air from their swim bladders through their anal duct, they produce a series of clicks. This "bottom-talk" allows the school to maintain tight formations and "chat" in total darkness without alerting predators who can't hear such high frequencies.