opae'ulas - halocaridina rubra
"Great info. So does this mean their life expectancy is a lot more than 4 years, and they are not sexually mature until 4 year or older? Very interesting read. Thanks."
Kevin
My original exposure to this was 8yrs. ago. In 2001, my gf (now my wife) bought a Migi-cube from a co-worker as a present for me. The Migi-cube was one of those inexpensive "self-sufficient" eco-sphere things and contained 4 opaes, a snail, and about 5oz. of water. The system wasn't completely sealed - there was a plug at the top for gas exchange. No instructions other than leave near indirect sunlight for algae growth.
Well, the snail died for lack of sufficient algae within 4 weeks. Ironically, by the 5th week, I had quite a bit of algae. Still, things were hardly in balance. Something went terribly wrong, the system probably crashed, and one by one, the opaes died over the next 9 months. The survivors turned cannibal until there was just one guy left. I'm pretty sure they didn't kill the live ones, just ate the dead.
I knew nothing about them at the time, not even their common and scientific names, and so it was tough to find out much about their ecology. I assumed they were just short-lived. But, that last guy lived in that death chamber for another 3yrs. all by himself, eating the algae that formed on the walls, and thinking lonely shrimp thoughts.
In 2005, I stumbled on more info about these opaes, did some research, ordered the 1/2gal habitat from fukubonsai, and dremeled the lone survivor out of the Migi and put him in with the 25 or so in the 1/2gal. He was different: smaller, paler - it turns out he had SHRANK because he wasn't getting enough nutrition during those first 4yrs.! I feel terrible about that.
Anyway, he lived happily with his new buddies (lots of bigger females in the 25) for the next 4yrs. and I could always tell him apart from the rest of them because he was the smallest. About 4 months ago, they started breeding. The kids grew up quick, and now I have a bunch of smaller opaes swimming around, so I can no longer tell him apart. He could be dead, he is 9yrs. old. Or he could still be alive and a midget.
To answer your questions: yeah, that first dude lived at least 9yrs. and may still be alive. As for sexual maturity, since I didn't change any of their water parameters, I'm assuming they came of age in August (which would make them ~4yrs. old), and then did what comes naturally.