Cudas are filter feeders?

[Steve_C]

A week ago while doing my safety stop off NC in 83 degree very clear water I watched some barracuda. There were probably twenty or thirty of them holding formation about 15 feet under water. Most about 2 -3 ft long so young ones. There were no visible bait fish in the area. Every now and then one would swim forward in a straight line opening wide and closing their mouth several times the whole time. The speed was way slower than when they strike. They would swim about 10-15 ft and then stop. There was not another cuda near their line of travel since all were pretty much facing the same direction.

What was this behavior? Were they scooping up zoo plankton? Trying to get more oxygen? I do not recall seeing this before.

 

[drbill]

Possibly flushing their gills?

 

[Steve_C]

Possibly flushing their gills?

To remove parasites? Is this a common behavior in some species?

 

[drbill]

I can't be sure that this is the case here, but I've seen a number of different species backflush their gills usually by opening their mouths and forcing water over the gill. Not sure why they do this. It could dislodge parasites. In a few cases it looked like they were eliminating fragments of kelp.