Metabetaeus lohena

[KenCotigirl]

Anybody have any experience with these. I can describe them quite unscientificaly as a large Halocaridina rubra with claws and they share the same brackish water ponds in Hawaii. Berried females seem common in literature. I have been told they are as hardy as the H. rubra. Have not seen larvae of this specie but have seen M. mcphersonae in print. Do the newly hatched zoea need full salt water? Plankton feeders?

[Mustafa]

I've had a few of them before, unfortunately all females with no male. Despite what others have documented, I have never observed them eat H. rubra or even chase them around. They seem to be omnivorous scavengers. Judging from the size of their eggs, it appears that their larvae are probably quite small and would have to be fed planktonic food. I don't know if they need full saltwater or not at this point; it seems likely as the larvae tend to drift long distances in the ocean before settling down as the M. lohena found on the Hawaiian islands appear to be genetically homogenous. H. rubra are a whole lot more diverse with apparently no genetic interchange going on between the various populations on different islands.

[KenCotigirl]

I obviously have a male and female since I have a shrimp with eggs. She never stays still for me to to get a very good look or take a picture. The eggs look smaller than H. rubra but not too much smaller. Grey black in color. Any thoughts on how long she will hold the eggs till they hatch? Assuming they are a low form any suggestions on keeping the larvae alive? Should I seperate the mom from the rest of her tank mates? I have given the adults the occasional spirulina flake but they seem only to take a taste then drop the flake. The H. rubra will then finish off the flake. What did you feed yours? Are the M. lohena as long lived as the H. rubra? Final question(s) for now: These shrimp live in anchialine ponds which have no direct surface contact with the ocean then how does the larvae get to the sea? The ponds are still water. How can the larvae negotiate the cracks, lava tubes etc to get to the sea? Other low form shrimp larvae float on stream currents to the sea.

[KenCotigirl]

A few of pictures of pregnant M. lohena and H. rubra.

H. rubra ready to drop

IMG_4176.JPG (226.25 KiB) Viewed 5326 times

[Mustafa]

Thanks for the pictures! I have seen ovigerous M. lohena females before and also think that the larvae aren't likely to be very small. In fact, even if they must be fed it probably won't be for too long before they develop into postlarvae. You could try to feed the larvae baby brine shrimp and see how that goes. I doubt anything in your tank will eat the larvae. If the larvae disappear it will be because they either died or developed into postlarvae and are running around. My M. lohena ate literally *anything*...flake, pellets, and even algae that I scraped off the walls of the aquarium. They *never* even attempted to catch H. rubra, so my observations cannot confirm some of the theories floating around out there that they feed on Opea ula. I'm sure they will eat dead Opea, but M. lohena's claws are way to small to catch any large shrimp with them. I'm leaving open the possibility that they may go for tiny postlarval Opae, though. As for M. lohena's longevity...no idea. I have not found any literature so far that mentions anything about age. Generally, though, cave-dwelling (and similar anchialine animals) tend to get rather unusually old.

There are actually connections large enough for shrimp larvae (and even adult shrimp) to move from these anchialine habitats to the sea. The connection to the sea in anchialine habitats does not always have to be just through tiny cracks in lava rock. There are plenty of anchialine habitats in the world that seem to have a deep, underground connection directly to the sea...even if it is through really large "cracks" in the rock. So, the deeper waters are much saltier than the surface waters in such places as freshwater is lighter than saltwater. I assume that the larvae move in and out with the tidal flows but there may be additional mechanisms involved.

By the way, when I visited an anchialine cave pool on the Island of Curacao in the Caribbean I discovered species of animals that weren't even supposed to be there...like the huge Macrobrachium carcinus, usually a river dweller, living in complete darkness in the cave (got there as a larva from the sea). There were also fish in that anchialine pool, which also entered the cave as larvae from the sea.

In any case, I've always wanted to breed M. lohena, and I'm confident that I can succeed, but I have not gotten my hands on some breeders yet (I must admit that I have not really tried all that hard finding them, either..). I hope you'll see some larvae soon and maybe even succeed at feeding them so they stay alive. Defininitely worth a try.

I obviously have a male and female since I have a shrimp with eggs. She never stays still for me to to get a very good look or take a picture. The eggs look smaller than H. rubra but not too much smaller. Grey black in color. Any thoughts on how long she will hold the eggs till they hatch? Assuming they are a low form any suggestions on keeping the larvae alive? Should I seperate the mom from the rest of her tank mates? I have given the adults the occasional spirulina flake but they seem only to take a taste then drop the flake. The H. rubra will then finish off the flake. What did you feed yours? Are the M. lohena as long lived as the H. rubra? Final question(s) for now: These shrimp live in anchialine ponds which have no direct surface contact with the ocean then how does the larvae get to the sea? The ponds are still water. How can the larvae negotiate the cracks, lava tubes etc to get to the sea? Other low form shrimp larvae float on stream currents to the sea.

[Newjohn]

It is always nice to see pictures.
Any updates ?

[KenCotigirl]

Staying positive, any update is a good thing. I would say that the female M. lohena holds the eggs for at least 2 weeks. I noticed at about the 2 week point that the eggs changed from grey/black to a clear space with a small black dot, the yolk nearly exhausted. The black spot was much larger than a developing eye so I do not think the spot was an eye. M. lohena have very small eyes like the H. rubra. The next sighting she was without eggs. No larvae have been seen to date. The two week period could be very inaccurate. 3 weeks is also possible but not 4 weeks.

Descriptions are difficult due to my setup. I purchased several pieces of broken coral from the LFS about tennis ball size. Not branch coral but more tube like coral thats all clumped together and creates many voids and caves. The H. rubra crawl all over the surface of the coral and actively scrape for food but the M. lohena like to stay in the caves. They dart in and out and stay in the shadows. Whenever they are in open areas they move rapidly as if they fear getting caught out in the open. When they shed their exoskelton they do not stay hidden in the caves. They are more exposed and cling to the bottom of the sponge filter for a day, maybe two. Is this hiding in plain sight but away from their M. lohena tank mates in the caves?

Females are quick to produce eggs after dropping a batch, about a month. The eggs of M. lohena are more tightly packed together, glued together, than the H. rubra. When a H. rubra fans her eggs you can often see individual eggs move. There is absolutly no movement in M. lohena.

The above described setup is not condusive to removing a female with eggs. A barren setup would work for removing and viewing shrimp but I think the M. lohena prefer the hiding places. They are not gregarious like the H. rubra. They seem more like crayfish and prefer elbow room. High densities may not be possible. I currently have 3 females with eggs. I am contemplating in the future starting a new barren tank. This way a female with eggs could be isolated and more easily observed. However these shrimp are $$ and not readily available and I am not keen on disturbing the status quo but I will see.

[Newjohn]

Thanks for the update.
Your detailed descriptions made me feel like I was there watching.

This thread will be a good reference for anyone that can obtain this Species.

[KenCotigirl]

New picture of a female M. lohena with eggs nearing release. You may notice that the eggs are not as tightly packed. When she moves the eggs also move a little. There is also a picture of the coral I was talking about.

[Mustafa]

Thanks for the update and the pictures. If you never see any larvae in the tank, not even of the H. rubra, then there are usually two reasons why. 1. too much feeding. Even if the shrimp are healthy and looking just fine larvae and young have a hard time dealing even with tiny amounts of water pollution and keel over quite quickly...larvae pretty much right after hatching. 2. The M. lohena may be eating all the larvae. That's especially likely if the larvae gather near the bottom after their lights turn off. Any, even weak, light source attracts the larvae and make them accumlate in one area. There, the M. lohena could just pick them up like candy in a jar.

I really hope that some larvae come out of this. The eggs of M. lohena are medium sized, and, hence, should have an abbreviated larval development. I'd say 2-4 weeks max depending on temperature.

[Newjohn]

Sorry for the question.
Are these what they were calling " Micro Lobsters " a few year back ?

[Mustafa]

No. The "Micro Lobsters" are just Opae ula (Halocaridina rubra). Micro lobster is just a (pretty unfitting, in my opinion) marketing name.

Sorry for the question.
Are these what they were calling " Micro Lobsters " a few year back ?

[KenCotigirl]

Additional comments. I have larvae and baby shrimp of H. rubra but have not seen larvae of M. lohena. I was wrong about the large dot in the eggs. I did not believe they were eyes. Pictures from 3 days later show greater differentiation in the egg. Now instead of one large black spot you can see two smaller eyes. Two pictures are from Feb. 6 and the other two are from Feb. 9. I am contemplating how to save any larvae if I see any from M. lohena as I do want to think about them being snack food.

Comment on marketing. As a cacti and succulent enthusiast we use scientific names. However the genus names like Opuntia are Ferocactus are not 'sexy' to the general public. The term 'Bunny Ears' and 'Barrel Cactus' are. So we live with it since it increases public awareness and allows the hobby to expand. Once the person is hooked we re-educate them to use scientific binomial names. I am sure the same applies to shrimp.

[ernopena]

Hey, Cotigirl, great pics!! Those are killer macro shots. I wish I still had 100mm macro lens for my Canon.

I don't have an Opae Ula tank right now, but when I did, I tried adding 3-4 drops of PhytoPlankton once a week to my tank when I had larva swimming at the top of the water column. I noticed they did slowly congregate in the cloud of blue-green water after a few minutes, but not in a swarming fashion. I think the larva fed on the phytoplankton. The adults definitely chowed down on the phyto. I wish I had taken pics to document it.

When I setup a new tank, I am going to experiment with feeding the shrimp phytoplankton and rotifers, in addition to spirulina and fish flakes. My buddy's girlfriend is from Oahu, and she said they feed reef food, specifically PhytoFeast and RotiFeast, to the Opae Ula in the tanks at the local fish store. I've never seen that mentioned before in any of the other shrimp forums, but it makes sense.

Maybe phytoplankton may work for your larva...

[Mustafa]

Comment on marketing. As a cacti and succulent enthusiast we use scientific names. However the genus names like Opuntia are Ferocactus are not 'sexy' to the general public. The term 'Bunny Ears' and 'Barrel Cactus' are. So we live with it since it increases public awareness and allows the hobby to expand. Once the person is hooked we re-educate them to use scientific binomial names. I am sure the same applies to shrimp.

Yes, of course, and I agree. However, my comment about "micro lobster" being unfitting was referring to the fact that Atyid shrimp (like H. rubra) don't even have lobster like claws, so maybe another name would have worked better. As you can see, when people see the M. lohena, which do have claws, they think that *that* may have been the "micro lobster" they saw on some website somewhere.