Latreilla valida pair

Latreilla valida pair

Postby FuEl » Mon Sep 01, 2008 7:14 am

Picked up this pair today. :lol:

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Postby mpedersen » Mon Sep 01, 2008 1:16 pm

Whoa, what the HECK are those?! I've NEVER seen this species of crab before. What's it related to?
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Postby aomont » Mon Sep 01, 2008 4:38 pm

When you put them in the tank take a picture from the front ! They look very interesting !
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Postby FuEl » Tue Sep 02, 2008 10:33 am

The crabs came from the Philippines I believe. Usually they burrow in the sand. Now they come out to feed. When threatened they raise their first pair of walking legs into the water column for defense. :lol:

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Postby FuEl » Thu Oct 02, 2008 10:37 pm

Slightly over a month after I got them, when I was losing confidence in getting this species to breed, I noticed the female paying extra attention to her abdomen. Turns out that she was carrying eggs! During the past month, she did not moult at all. Happens that this species can mate somehow without the female moulting? :shock:

I moved her to a hatching chamber just in time. She started releasing shortly after midnight. :lol:

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Postby FuEl » Thu Oct 02, 2008 10:41 pm

Photos of the zoea.

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Postby FuEl » Tue Oct 07, 2008 9:12 am

New findings. Megalopa stage is reached in 5 days. Notice the top right picture, can see the blurry chelipeds. :P :lol:

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Apologies as I do not have a microscope, pics were taken using a digital camera.
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Postby tcmfish » Tue Oct 07, 2008 11:33 am

Nice! keep us posted
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Postby FuEl » Thu Oct 09, 2008 2:37 am

Pics of the megalopa at 7 days. The red things are frozen cyclopeeze for comparison. :lol:

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Postby FuEl » Sun Oct 12, 2008 12:37 pm

All megalopa died at 11 days. Might have aerated them too much initially. Now just have to wait for a second try. :(
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Postby spawner » Sun Oct 12, 2008 2:09 pm

How many days were they megalopa? They might need to be moved to a settlement area or need a settlement cue.
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Postby FuEl » Sun Oct 12, 2008 11:21 pm

Hi Andy,

Their larval duration was short. They reached megalopa around 5 days, with 2 distinct zoeal stages. I bought the book by Calado which he recommends a circular settling tray but with so few individuals (around 20) which were at megalopa I did'nt think that was neccessary. As there is no information on this species as yet, I guess I will have to keep trying. Btw, you happen to know how vigorous I should tune the aeration? I treated them like Lysmata larvae, tumbling them around with the fine bubbles from a wooden airstone. I think that might have done them in somewhat. :oops:

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Postby spawner » Mon Oct 13, 2008 4:46 pm

Did you read my paper on the Mithraculus juv? We used 3" PVC and put screens on the bottom to make enclosures. No air inside the enclosures. I'd suggest that they need 2-3 more days in megalopa to become competent. Did you notice a behavioral change? From buzzing in the water column to moving to the bottom of the tank?
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Re:

Postby FuEl » Tue Oct 14, 2008 6:20 am

spawner wrote:Did you read my paper on the Mithraculus juv? We used 3" PVC and put screens on the bottom to make enclosures. No air inside the enclosures. I'd suggest that they need 2-3 more days in megalopa to become competent. Did you notice a behavioral change? From buzzing in the water column to moving to the bottom of the tank?


Did'nt come across that paper Andy, was'nt aware of such a paper. :oops: Perhaps you could provide me with the link?

Is there any advantage of the screen bottom compared to a solid smooth bottom besides letting the detritus fall through? Does the mesh bottom provide some sort of tactile cue for the megalopa to metamorphose successfully? I know for blue swimmer crab megalopa, netting is used to encourage them to settle.

I did notice a behavioral change, late stage megalopa stopped buzzing around and stayed at the bottom. :)

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Postby spawner » Tue Oct 14, 2008 8:43 am

Well I personally think that a mesh bottom does two things, one it allows water flow, but the other is an important tactical cue. If you let Mithraculus settle in a rearing tank you get marginal results, if you put them on screens they settle out and have a substrate right away. With out substarte they clump grabbing each other.

You need to move your larvae the day before you noticed the behavior change. That is the point where they are competent.

Penha-Lopes, A.L. Rhyne, J. Lin and L. Narciso, Effects of temperature, stocking density and diet on the growth and survival of juvenile Mithraculus forceps (A. Milne Edwards) (Decapoda: Brachyura: Majidae), Aquac. Res. 37 (2006), pp. 398–408.



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Postby FuEl » Tue Oct 14, 2008 9:29 pm

Thanks Andy,

Will try the mesh bottom for the next batch. Now the hard part..predicting when the female will release again. No moults to help me keep track! :(
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Postby aomont » Sun Nov 30, 2008 5:49 pm

Any progress with this pair FuEl ?
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Postby FuEl » Mon Dec 01, 2008 12:27 am

Hi Anderson,

I have been focusing on the dottybacks and clownfish. It's much easier to obtain larvae from them compared to the crabs. The crabs have never moulted since I got them so it is very hard to predict when the female is due for release. The only hint I can get is when she starts fanning the eggs, usually the hatch occurs soon after. That said, I have'nt had time to observe the pair much as they are mainly nocturnal. They only come out from beneath the sand after lights out.

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