Word for "opening and closing the mouth?"

Question

Example:

The stranded fish were flapping desperately on the sand, their mouths closing and opening, seeking for the water that wasn't there.

Is there's a word that means opening and closing the mouth? I thought of gaping but I think it only means keeping the mouth open?

Answer 1

The idiomatic way of saying this is

The stranded fish were flapping desperately on the sand, gasping for breath.

Answer 2

To gulp: (from TFD)

• to gasp, as if taking large drafts of a liquid.

Fish gulping for air:

• After feeding time all the other fish are on the surface gulping or gasping. Sometimes this happens later in the day as well.

( from www.fishchannel.com)

Answer 3

The term for the action a fish uses to "gasp" for air is called buccal action pumping. I am wrapping up a conservation biology degree with focus in fishery science at CSU. Here's some information:

dual pump: buccal and opercular action operating in tandem drives water in a nearly continuous unidirectional flow across the gill curtain between them

• the suction phase begins with compressed buccal and opercular cavities and closed valves
• as the buccal cavity expands, the internal oral valves open and water moves into the buccal cavity and across the gill curtain
• during the force phase, the oral valve closes and water is forced out through the opercular valve

Source: https://www.shsu.edu/~bio_mlt/Chapter11.html

A good image of this action can be found here: