To catch a predator!?

[RoxyDog]

Ok, I'm pretty convinced my can't-keep-a-shrimp-alive problem is not temperature or my water.  So either my clowns suddenly took a liking to shrimp, or I have a mystery predator!     Only shrimp are affected, no snails/hermits/"good" crabs/fish.
I know some of you have found bad crabs etc in your tank and I wondered if it was by accident or did you go "hunting"?  Any ideas on how to catch a bad guy would be appreciated.  And does anyone think it's possible that a large serpent star in a small tank (who seems to eat any kind of food I put in there) would prey on live shrimp?

[mdugly]

Serpents are known predators of fish/shrimp...
I have seen a pic of serpent after eating a shrimp - was almost unbelievable how it expanded to almost twice it normal size to swallow it whole.

[RoxyDog]

I never knew that...hmmm...maybe he was my problem!

[redbelly]

Almost all serpent stars are reef safe actually and are not predatory.

Here is a quote from an article by Anthony Calfo with regard to the serpent starfish:
Ophiuroids - Serpent Stars: with the exception of basket stars (see overview of Crinoid feather stars below as similarly challenging), the majority of serpent and brittle stars are hardy and suitable for home aquarium life. Many will fare well even in smaller aquariums (under 20 gallons), provided that they are target fed at least weekly. Most are harmless, if not helpful, in reef displays as innocuous bio-turbators (sand-stirrers), eating particulate matter or at least keeping it in motion or suspension for nutrient export processes such as skimmers and mechanical filters. They are the least discriminating and most adaptable feeders of all "starfish." Unlike other popular clean-up creatures (hermit crabs, perhaps most notoriously), Ophiuroids are only a light burden on the bio-load and bio-diversity of the system. Numerous species in this class are suitable for beginners.



Specific type or serpent starfish are predatory actually. Most notably the green serpent start fish often refered to as the "green serpent of death" starfish.

Here is a quote from an article by Anthony Calfo:
"Ophiarachna incrassata, the infamous Green Brittle Star, and a few related kin are the rare exceptions to the otherwise reef-safe and well-behaved Ophiuroid serpent and brittle starfish class. In some tanks O. incrassata will behave for months or even years, while in other tanks they tend to catch and kill motile creatures whenever possible They are active predators, which arch their central disk above their legs to form a trap for fishes and other prey. "
http://www.reefkeeping.com/issues/2004-06/ac/feature/index.php

[RoxyDog]

yeah, I read that too, but I also read that they CAN be opportunists.  I wonder though if he didn't get enough to eat and found the shrimp easy prey in such a small tank, being that he was so big?  I still have the little orange guy I got from you Pat, who I never see.  this big red guy was very very active.  so, if it wasn't big red, any ideas about finding another possible predator?

[Julie]

I think I have a big red or purple not sure what colour he is and he has never paid attention to my shrimp and it's been a couple years.  He's large and particularly fond of the turkey baster as it brings treats.
What about a trap - do you ever hear clicking or see a snail or crab mysteriously being thrown on it's side?

[RoxyDog]

I've heard clicking, but think it was just snail/thermometer/etc..against the glass.  the snails and hermits and other crabs are all fine.

[Tyler.L]

the clicking could actually be a pistol shrimp that hitchhiked its way in

[rockgarden]

I've uploaded a photo of a trap that I think Nelson had which will give you some design ideas if you are wanting to build something fancy for your purpose.   The trap in the photo would be too large for your small tank but might give you some ideas anyway. The very, very small souvenir lobster traps that you can buy in Nova Scotia also good for trap design ideas.  Basically you want something where the critter goes in and doesn't get back out.  I had a mantis shrimp hitch hike in my original reef and it lived there for about five years.  Heard it often.  Saw puffs of rock dust come out of holes every so often as it made its cavities and hiding places larger but I only got to se it a couple of times and then only a quick glimpse.  Eventually decided that it was knocking off snails form time to time but didn't seem to be affecting the hermit crab or fish population but by all other accounts that I have read, you don't want one in your tank under normal circumstances.

http://www.flickr.com/photos/rjhayphotography/2168513913/

Best of luck with your mystery.

Ron

 

[RoxyDog]

Ok, so I think my big red serpent star was the predator I was looking for.  A big serpent star in a small-ish tank that's not overfed (fish fed every 2 days, anemone/inverts once or twice a week) = possible bad idea.

I tried a few things before deciding Big Red was probably the problem.  I got a shrimp from another person's tank to reduce the possibility of stress from shipping, etc.  Acclimated said shrimp well, and into a critter keeper he went in my tank.  This was to be able to watch him for signs of illness and to make sure my water wasn't the problem.

Just so happens @ this time I decided to find my big serpent star a home b/c well, he was simply too big.  Out goes the star fish.  Next, I search day and night for anything out of place.  Then, I try a trap with a raw shrimp and all I catch is my other small serpent star, a hermit and a nassarius snail.  So I let the shrimp out.  A week later he is alive and well.  Hopefully all continues to be well with him, after all it hasn't been that long. 

I'm not saying ALL serpent stars are bad, and I'll keep my little guy for now.  I think the key was the small tank with the big star fish.

[veron]

in this hobby the rules will be broken by our creatures sometimes.
but,,, how are you acclimating you shrimp? are you checking the salinity from whence it came? number one mistake many make is NOT checking the store salinity which is notoriously low. combined with many stores do not acclimate very well either. but, funny thing is your snails are all doing well

[mdugly]

Possible your red serpent was one of these ?

Reef Invertebrates, page 345:
Ophioderma squamosissimum. The Red Caribbean Brittlestar. This beauty will predate on small motile invertebrates if not kept properly fed.

[RoxyDog]

certainly could have been?  I'm not sure if all red brittle/serpents are the same kind, but it looks similar.  quoting wetwebmedia:  "The Red Caribbean Brittlestar (Ophioderma squamosissimum) or (Ophioderma rubicundum) are particularly striking and generally well behaved if well fed. If not well fed they can be predatory, but these species are the least predatory and among the best of the brittlestars. "  I don't think mine was "well fed".