It is a highly coordinated behavior achieved by the dorsal rotation of the dermatocranium, lateral expansion of the suspensorium, and the depression of the lower jaw and hyoid.

In addition, the derived trait of anterior protrusion via the premaxillary bone in the upper jaw is acknowledged to increase the force exerted on the prey to be engulfed.

This diversity in relative use is quantified using the ram-suction index (RSI) that calculates the ratio of use for ram and suction during prey capture.

Extreme suction feeding is demonstrated by sit-and-wait predators that rely on rapid depression of the jaws to capture prey (e.g., frogfish, Antennariidae).

A predator with a small mouth aperture can generate strong suction force compared to an individual with a wider gape.

[19][18] This was demonstrated by Wainwright et al. (2007) by comparing the feeding success of the bluegill sunfish, Lepomis macrochirus, and the largemouth bass, Micropterus salmoides.

This can be accomplished by means of a swept-back mouth, as in balaenid whales,[21] or by allowing water to flow out through the gills, as in sharks and herring.

The fish all open their mouths and opercula wide at the same time (the red gills are visible in the photo below—click to enlarge).

[24] Biomechanically this is a unique and extreme feeding method, for which the animal at first must accelerate to gain enough momentum to fold its elastic throat (buccal cavity) around the volume of water to be swallowed.

Jaw protrusion is the outward movement of the premaxilla or mouthparts towards the prey, which is achieved via more mobile mechanical linkages in the articulations of the mouth.

Another example of protrusion is seen in dragonfly larvae (nymphs), which have hydraulic lower mandibles that can extend rapidly, protruding forward to catch prey and bring it to the top jaw.

[28] With prey capture times of down to 5 ms (shrimpfish Centriscus scutatus) this method is used by the fastest feeders in the animal kingdom.

The secret of the speed of pivot feeding is in a locking mechanism, in which the hyoid arch is folded under the head and is aligned with the urohyal which connects to the shoulder girdle.

These are contrasting methods for the removal of food particles from a water flow: for example, by the gill rakers of fish, the baleen of whales, or the ostia of sponges.

In filter feeding, the water flow is primarily generated by the organism itself, for example by creating a pressure gradient, by active swimming, or by ciliary movements.