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For a couple of months I’ve been hoping that the offspring of the orange shrimp would color in as they reached maturity.  They’re about half-grown now, and they’re all still shades of brown and clear.

For comparison, here’s a photo taken of a parent under the same lighting conditions:

Possibilities I can think of are

1)  The orange color is a recessive trait, and even though the mother was orange, she coincidentally (and repeatedly) mated with a homozygous clear male.  That seems pretty unlikely.

2) The young need to grow up more before they’ll display the orange color.  Possible, but the largest of the new generation are approaching the smallest orange members of the older generation.

3) Color is the result of parasitic infection (a parasite that really, really wants to be eaten.)

4) Color is dietary.

5) Color is the result of some dying process done by the importers.

#4 and #5 (or a combination) seem the most likely, but that raises questions as well.  How could a bright coloration like that persist for months through repeated molting?

#3 I can try to test by raising the new generation in close quarters with the parents.  However, a “wants to be eaten” parasite surely requires one or more predators as part of its lifecycle, and that’s going to be pretty hard to simulate.

#2 Would be obvious in another few months.

#1 Is fairly easy to test, but will take a long long time,