The largest animals of all, blue whales, are intermittent ram feeders. So are all the other baleen whales. That means they open their huge mouths and surge forward, engulfing tons of water as their pleated throats expand. They force the trapped water back out through the baleen fringes, which snare edible particles in the process. Whales don't make this mighty effort unless the water holds plenty to eat.
Basking sharks are continuous ram feeders.
Oversized jaws agape, they swim for hours through thin and thick swarms of zooplankton. Because their oceanic prey sometimes is found near the surface during daylight hours, these sharks looked to sailors as if they were basking in the sunshine. That behavior gave them their name, and also explains why the unusual visitor was easily spotted from the bridge of the Alpha Helix . Its mouth was in an animal soup while its fins jutted above the surface. Unlike whales, ram-feeding fish have no baleen.