Mystery shrimp larvae -- long

fish farmer

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Hi,

I am currently culturing a batch of shrimp larvae that I thought were L. amboinensis because I collected the larvae from a tank that had 2 L. amboinensis adults. One had fertile eggs for ~ 2 wks. (and had hatched larvae in the past) and when I figured they would hatch, instead of larvae I saw its molt and figured either it molted with the eggs still attached or all of the larvae were eaten before I could collect them. I doubted the latter though because I only had an airstone in the tank with 3 shrimp and some hermits/snails... and also because I have had some survivors from previous batches in the same amount of time (mid-morning).

Then, 2 nights later I was examining the tank and saw shrimp larvae swimming around!! 8O I just figured they were L. amboinensis, collected them and have been rearing them ever since (29 days now).

Okay, here's where it gets strange -- After I collected the larvae out of the "broodstock" tank, I noticed the other smaller L. amboin. had eggs which were fertile. Then about a week later, my larger adult died. All other tank inhabitants fine. Smaller shrimp released eggs/larvae which I collected. But as I collected them I noted that they did not look the same as the larvae I had collected previously!

I was examining both sets of larvae today (the younger batch is 11 days old) and they are most definitely different. The older batch are half the length of the L. amboin larvae, they are not as "spidery" looking and they look like a dark brown color when looking at them in the tank. When I remove one and look at it in a glass beaker, it is yellowish in color. The eyes are not nearly as "stalked-looking" as the L. amboin.

So... my question is: What type of larvae could these be??? I really wish I could post a pic. They are ~0.5 cm or so. The only animals in the tank are (now one) L. amboinensis, one R. uritai, hermit crabs and snails. Does anyone know what R. uritai larvae look like? And if the larvae are R. uritai, how did I get eggs/larvae from a single individual? I've had all of these critters in the same tank for about 2 months now.

Sorry for the long post, but I am baffled!

Thanks in advance for any info. anyone can give me.

K
 

croaker

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Sorry, I don't know too much about shrimp larvae because I culture fish. Have you done any water changes and where did you get that water? Maybe these larvae came in with the water if you didn't make it or buy it. Maybe it's a hybrid of L. amboinensis and R. uritai...who knows. Interesting though. Hopefully you will get a good survival and be able to ID them that way if not before. Good luck and sorry I'm no help!
 

fish farmer

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A few of the larvae are starting to form pincer-like appendages that they keep pointed up along their heads (like if you put both your arms straight up toward the sky held close to your head). I'm thinking they're hermit crab larvae... Does anyone know when they settle -- when I should start putting substrate in and/or very small shells??? I figure I've spent all this time rearing them, may as well see them through to "the end" of metamorphosis if they are willing. :D

Croaker -- I use only artificial seawater, so they didn't come in through the water, but thanks so much for the reply. :D

I'm looking to get a scope sometime soon, and maybe I can get pics of them before they either all die or settle into shells. Not particularly interested in rearing hermit crabs, but it's been interesting.
 

croaker

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Fish farmer,
I didn't even think about the hermit crabs you said you had in there. I have no idea how long it takes them to settle but just keep on eye on them and hopefully you'll get lucky and have a few survive. Good luck and if you do get pictures I'd be interested in seeing them.

Christine
 

spawner

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Oh she is CUTE; my wife can never see your avatar.

You can send me some perserved if you want them ID.

andy
 

spawner

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One more thing, change your name, these are more interesting than fish larvae. "Fish farmer" so bias, the injustice.
 

lusoreef lda

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Hello,

The L. amboinensis larvae has several zoe (stages - at least 14) that can last up to 3 months before the final molt (when they settle and become a small shrimp).

The first stage is about 600 microns and has the eyes close to the head.
The second stage (zoe) splits the eyes and they become litlle ET´s.
The third stage shows splitting in the rear fins.
The fourth stage shows appearance of the first "legs"
And so on...
Untill they reach the final stage in which they are about 2.5-3 cm, have long rows, and begin mark time molting (God knows why!) :(

In first 8 stages (at least) each zoe last around 3-4 days.

So the older larvae you have should look different from newly hatched larvae.

Hermit crabs also have small larvae which look different from the shrimp larvae.

They will most probably have 4 zoe before the final megalopa stage (final stage when they are not larvae nor crab)

Hermit crabs need small shells when they settle, or they will not settle at all (they start mark time molting aswell). I´ve tryed with small shells (1-2 cms) and they seemed to work fine.

The reaction you saw on the amboinensis, which had the eggs attached to the molt, usually means they had a stress reaction which caused them to molt early (salinity changes, Temperature change). Another cause is lack of good food (protein and lipid deficiency in feeding), or old age. Usually a shrimp has 3-4 years to live.

Kind Regards :p ,

Brian
 

fish farmer

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Thanks for all the info Brian!

The larvae were in fact hermit crabs and they have grown to the megalops stage and then settled to the bottom.

My amboinensis larvae also did well until I had to leave town for over a week. Oh well. Fortunately, my adult shrimp have eggs every 14 days or so, so I will try again very soon.

Thanks again for the reply!!

K
 

fish farmer

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I had about 4 of them actually make it past metamorphosis and settle. They were pretty cool looking. :D

Then I had to leave town and they didn't make it while I was gone, despite having someone feeding them, etc.

It was fun while it lasted though and very interesting.

K
 
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