Blue shrimp ID?

[SurlyDiver]

Is this a Shortscale Eualid (Eualus suckleyi)? What could cause the amazing blue pigmentation?

This pic was taken at Three Tree Point last week on a deteriorating stump at about 30 fsw.

[SurlyDiver]

There was at least one other nearby that had the same blue coloration.

[Dusty2]

Very nice photo. I'll let Greg say what it is. He's the expert

[LCF]

I'm no shrimp expert, but I wonder if that's another Heptacarpus brevirostris, like the deep green one I posted a few days ago? They apparently come in a wide range of blue-green colors.

[SurlyDiver]

Thanks! It seems to have more of a pattern than Stout Shrimp that I've seen. It has white bands on its legs though they're not very noticeable. I have seen some Stout Shrimp trend toward blue, too, but it's uncommon I think, based on my limited experience with looking at shrimp. I'm mostly curious about what would turn it blue.

[Greg Jensen]

It's another stout shrimp, Heptacarpus brevirostris. Color in these shrimps is largely due to chromatosomes (groups of pigment-bearing cells) that can be expanded or contracted, kind of like the chromatophores on an octopus but nowhere near as fast. They can also have a greenish to turquoise colored meat, which is likely something derived from their diet.

Some Deep blade shrimp (Spirontocaris prionota) change quite dramatically at night to a beautiful blue-green color, but I have no idea why some individuals do it and others don't.

[SurlyDiver]

Thanks for the info, Greg. I'll keep an eye out for them and see if I can notice any trends. Time of year, habitat, varying hues, and the like. If it's diet related, do you have a theory on what would force blue pigment? If it is a chromatophore, what is the purpose of it?