By Hanae Armitage

They travel in massive hordes, are a keystone ocean species, and even show a little glitz. Yet anchovies are primarily known for being a commonly picked-off pizza topping.

The 144 oily species of anchovy make up the the Engraulidae family, and are a paramount contributor in maintaining the balance in marine life populations, especially in temperate waters. A huge range of fishes, birds, and mammals depend on anchovies as a main food source. These little fish even satiate some of the ocean’s most enormous critters, including humpback whales.

Anchovies inhabit the Atlantic, Indian, and Pacific Oceans, and spawn their transparent, buoyant, sausage-shaped eggs during the summer months when the water is warmer. Shortly after fertilization, the tiny hatchlings are born, just under a half-inch long. Typically they grow to 5 inches, but can reach a sizable (in the anchovy world) 18 inches.

Up close, anchovies have an obvious green hue, but a single silver stripe spans their body, creating a shimmery, metallic appearance. Their average lifespan hovers around four years, but some have been recorded to reach the ripe age of seven.

Anchovies typically eat plankton and fry—newly hatched fish. To feed, they swim through the ocean with their mouths agape, appearing perpetually surprised. Since their yawning mouth lets in a significant amount of non-edible junk, a filtration system separates food from common ocean muck. Once food and muck are separated, their teensy, razor-sharp teeth munch down the sustenance.

Because they’re rather helpless on their own, anchovies employ the “safety in numbers” survival strategy. These little fish have to band together to have any hope of surviving. They congregate by the thousands and cruise the ocean in tightly knit schools. Their goal is to deter predators with sheer magnitude.

When predators attempt to feed, the anchovies form a defense mechanism known as a bait ball — a violent swirl of thousands of fish trying to overwhelm and hinder predator success. The bait ball also protects against easy, individual pick-offs. While a massive, whirling tornado of thousands of glinting life forms isn’t particularly inviting, hungry marine mammals gets their fill of these salty morsels, keeping the predator-prey balance in check.