More Mystery Shrimp! - 10/04/2005
Hello,
<Hi!  Sabrina the slightly shrimp-obsessed with you today....  And please let me apologize for the extreme lateness of my reply; on top of having been sick and missed some emails in my box a few days back, you've really given some perplexing pictures!  Excellent photos, I must add.>
I have seen this question before ("Mystery Shrimp - Fun with Freshwater Inverts") but I would like to ask it once again... is what I have actually a ghost shrimp?
<Not what is commonly considered to be a ghost shrimp, but it does look like a Palaemonetes species to me.  Perhaps P. antennarius - your shrimp seems to have the same bizarre iridescence that they exhibit.  They do develop markings like yours shows as they grow, but yours is more prominently marked than ones I've seen.>
or is it a "long-arm" - Macrobrachium... because this guy's arm's aren't longer then his body, but he is a bit big to be a ghost shrimp. He is about 4.5cm (1 3/4").
<Not a Macrobrachium, as far as I can tell, but not a "common" "ghost shrimp".>
I have posted photos here: http://www3.telus.net/public/al_s/ShrimpPhotos/  I am wondering what the morphological difference is between the Macrobrachium and the Palaemonetes?
<Well....  See, you're asking tough questions now!  Just kidding, this is a good one.  To be quite honest with you, I do not know the difference in systematics between these two genera.  They are both in family Palaemonidae, though Palaemonetes shares the subfamily Palaemoninae with a few other genera, whereas Macrobrachium is not in that (or other) subfamily.>
is it just the length/size of the pincer arms or am I missing some other key item?
<Macro = big, brachium = arm ....  All of the shrimps of genus Macrobrachium do have very prominent "arms".  Some more so than others, to be sure, but all are quite big.  This can be somewhat less noticeable in females, but even most females have really big arms.  Also, all of the Macrobrachiums (Macrobrachia?  Uhh, I don't know the pluralization of this word!) that I have met seem to have an impressively large rostrum.  Some Palaemonetes do as well though, including P. antennarius, whose rostrum can be quite wicked-looking.  Physically, those two pincer arms will tell all.  Or most, at least.  Yours is not a Macrobrachium, as far as I can tell.  Now, that doesn't mean it's not aggressive!  P. antennarius, if it were just the size of a dog, would take over the world and wipe out humanity.  And you'd hear an evil laugh while they did it.  Fortunately, they stay at or under 2", so hopefully we're safe.  Or maybe that's just what they want us to think....>
Thanks,  -Rose
<And thank you for showing us these great images; I do hope you enjoy this animal.  Wishing you well,  -Sabrina>

Differences between Palaemonetes and Macrobrachium species shrimps....  9/21/05
Hey Bob!
<Sabrina>
I know I should know this, or at least be able to find it, but I don't and I can't.  I wonder if you know, or
can point me in the right direction.
<Will try>
What, physiologically, ARE the differences between these two genera?  I mean, aside from the (macro) big
(brachia)" arms"/pincers, what really makes a Macrobrachium a Macrobrachium?  What makes a
Palaemonetes a Palaemonetes?  Both are of the same family (Palaemonidae), though Macrobrachium is in
sub-family Palaemonidae....  But....  What determines this?  I've struggled a couple days to try to find
*something*....  hobby-related websites and the few books that mention shrimps (including Uwe Werner's
Aqualog) just talk about care, and those big honkin' arms....  and I can't seem to find any scientific
websites that really explain what makes a Macrobrachium a Macrobrachium, or a Palaemonetes a
Palaemonetes.  Any thoughts?  I wish/hope it could be as simple as counting scales, rays in fins, tooth
shapes and pharyngeal bones....  Fish are so easy
<.
<Don't know... w/o "looking"... likely at SIO... but here is the feedback from Google on Systematics of the Palaemonidae:
http://www.google.com/search?sourceid=navclient&ie=UTF-8&rls=GGLD,GGLD:2004-27,GGLD:en&q=systematics+of+the+palaemonidae
Looks like there are some useful bits here... and I would try the (not ready
for prime time) "Google Scholar" as well... Next time you're in town, let's
make a sojourn down to the Scripps Library... am facile at searching "the
literature". Bob F>
Thanks much....
-Sabrina

Macrobrachium rosenbergii information
Robert,
Around 14 years ago I purchased three "Blue Lobsters" from a pet store in Mt. Pleasant, MI. Later on I learned that they were known as Macrobrachium rosenbergii. These three invertebrates were the most interesting aquarium pets that I had ever owned. They are long gone now, but I recently purchased a 125 gallon aquarium which I intend to put my larger Cichlids in.
Thinking about what to put into the empty 55 gallon, I remembered the "Blue Lobsters" which I loved having in the past. My question is where can I purchase them??? I can not find them anywhere in the West Michigan area.
Whenever I ask pet shop employees they look at me like I am crazy!! If you might have any information that might be helpful please e-mail me back.
<These crustaceans are still about, though not near as popular as they were years back. This one species is widely and intensively cultured as a food organism (mainly in the Far East). It and a handful of new species of interesting prawns, shrimp and true lobsters can be had from larger retailers and etailers. Please contact the folks on our Links Page here: http://www.wetwebmedia.com/links.htm to start your search, and ask your local fish stores if they'll please look, special order one, more for you. Bob Fenner>
Thank you,
Andy Shearer

Mystery Shrimp - Fun with Freshwater Inverts Hey all, <Hey, Chris> I have a rather odd hitchhiker that came with my bumblebee shrimp today. It's about the size of a large ghost shrimp, it's pincer arms are about as long as it's body <This alone screams "Macrobrachium!"  Now, Macrobrachium *what* is the question.> and are sort of banded in alternating pale red and grayish-black. LFS said it'd snuck in with the bumblebee shipment and hadn't injured/killed any of the bumblebees in the couple weeks it had been in their tank at the store, but they're not sure what it is. <Fun!> Well, due to various chaos today involving having to return/exchange the tank I got for Xmas (Marineland 10gs apparently have different dimensions than All-Glass 10gs), having to take relatives to the zoo for their annual Zoo Lights event, discovering I either need to buy an adaptor for the power cord and/or change the outlet the tank was going to be plugged into, my new 10g didn't get set up like I'd planned it to be. <Boy, when things go wrong!> So, for the night, the bumblebees (and unknown) all got placed in a 1 gallon tank with an airstone and some algae wafer bits. A short time later, both my sister and myself observed this unknown shrimp would wander the perimeter of the tank trying to pinch the tails of all the bumblebees (who'd jump out of the way). <Oh yes.  Macrobrachium shrimps almost all are aggressive meat eaters.  Fish, shrimp, anything that holds still long enough to be nabbed, are all at risk.> So the unknown got moved to a separate 1g, where he's mostly watching the bumblebees in the tank next door. <Dreaming of snacking, I'm sure.> (The bumblebees now appear much happier, munching away on the algae wafer and exploring instead of sitting in groups along the walls) <Probably feeling a touch safer, now that they're not potential meals!> So, can anyone ID this critter? <Your photos are quite unclear (no offense, just an observation) and therefore very difficult to tell anything for sure....  is it possible to get him into a position against a solid background?  It'd be especially nice to be able to see his first pair of legs, their shape, color, etc.  From what you've given me, the best rough guess I can give you is Macrobrachium japonicum.> I'm probably going to try and take him back, unless someone can convince me he'd be better behaved in the 10g with the bumblebees (and future fish inhabitants) rather than how he acted when stuffed into a 1g with them. <I would not expect him to change his ill manners, not at all.  But it certainly might be fun to hang on to him in his own tank, see what he grows up to be!  I'm sure he'll worm his way into your heart, even with an unbeatable appetite and a bit of a bad disposition.> I'm hazarding a guess it's some kind of Macrobrachium, perhaps? <Almost definitely.> The object it's sitting on in the photos is an airstone if that helps with scale at all. Given the day it's been, you're probably going to tell me I just got a future 5" monster shrimp that eats fish or something ;) <Well....  ;)  I do believe you're reading my mind!  I'm not at all certain on his ultimate size, though.  I'd guess somewhere in the neighborhood of a couple of inches.  Small fish would likely be at risk, and small shrimp, as you've observed, certainly aren't safe.  But again - don't give up on him just yet!  He may prove to be an endearing little dude, well deserving of his own tank.  Give him a chance, if you can.> Thanks again for any help you're able to provide,  Chris <You betcha.> --Addendum-- A friend located this photo that sort of looks like the unknown shrimp:  http://www.shrimpcrabsandcrayfish.co.uk/Shrimp.htm?Longarm.htm~mainFrame  (scroll down to Striped-Hand Prawn and click on the image). Although this site's photo is a bit redder than the one I have appears. <This picture looks very much like Macrobrachium japonicum to me.> And it seems to be the only site on the internet that uses the name Striped-Hand Prawn (aren't common names fun to deal with?) <Ugh.  I think the world would be a far less confusing place if we simply scrapped ALL common names.  *sigh*> Also, I already checked through the photos at  http://www.wirbellose.de/arten.html#Großarmgarnelen   to try and ID it with no luck (Remembered the site from when it was pointed out to me in the forums by vintage_fish <Hey, that's me!  ;) > several weeks ago in regards to a different species) <Try this one:  http://www.wirbellose.de/arten.cgi?action=show&artNo=220 .  Do please look very closely at the faint striping on the legs (I bet this is a juvenile or young female) and compare with your shrimp.  Also, try a Google search on Macrobrachium japonicum and check out some of the pics that come up.  If at all possible, try to get a clearer pic on a plain (perhaps black) background.  In any case, a fun little fellah to find out more about, if you can spare a tank for him!  Wishing you well,  -Sabrina>