Groupers typically have a stout body and a large mouth. They are not built for long-distance fast swimming. They can be quite large, and lengths over a meter and weights up to 100 kg are not uncommon, though obviously in such a large group species vary considerably. They swallow prey rather than biting pieces off it. They do not have many teeth on the edges of their jaws, but they have heavy crushing tooth plates inside the pharynx. They habitually eat fish, octopus, crab, and lobster. They lie in wait, rather than chasing in open water.
Their mouth and gills form a powerful sucking system that sucks their prey in from a distance. They also use their mouth to dig into sand to form their shelters under big rocks, jetting it out through their gills. Their gill muscles are so powerful that it is nearly impossible to pull them out of their cave if they feel attacked and extend those muscles to lock themselves in.