What Marine Organisms Are Filter Feeders?

What exactly is a filter feeder? Filter feeders are animals that obtain their food by filtering water through a sieve-like structure that catches food particulates. Filter feeding only works in water, and most filter feeders are found in marine environments (meaning they live in the ocean).

A wide range of marine species use filter feeding as a strategy. Filter feeders can be motile (meaning they can move by themselves) or non-motile (meaning they remain in one place unless moved). They can be small enough to fit in the palm of your hand, or larger than a car.

All non-motile filter feeders are also invertebrates, or animals that lack a backbone. These include sponges, tunicates, and bivalves like oysters and mussels. Non-motile filters feeders feed by pumping water through gills or other structures in their body, which brings in a constant flow of food particles.

In some habitats, filter feeders like oysters play a big role in removing toxins and other particulates from the water column. Their filters catch not only food, but also pollution, sediment, and other tiny debris. This helps keep the water clean and healthy for other organisms.

Motile filter feeders include massive animals like whale sharks and baleen whales. Whale sharks feed by swimming with their mouth open and pushing water through their gills. Baleen whales, on the other hand, feed by gulping huge amounts of water that contains krill or other food items. They then force the water out through their baleen (a stiff, comb-like structure), which allows the water to escape but keeps the food inside.

The largest animal to have ever lived, the blue whale, is a filter feeder. Blue whales are so large that an adult human could crawl through their aorta, yet they feed on tiny creatures like krill that are almost too small to see without a microscope.