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Old 09/23/2009, 12:42 PM   #2
The Hardy Mongolian Pony
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Join Date: Nov 2008
Location: Dallas, Texas
Posts: 1,372
Thurge you beat me to it. We've needed this thread for so long, hopefully it will be stickied.

So how do you know if you have a stomatopod in your reef tank?

It should be noted that you must know there is a mantis before attempting removal. If there isn’t a stomatopod in your tank, well, you’re just wasting your time. The familiar claim is “I keep hearing a clicking noise at night coming from my tank.” God knows, this could be anything. I’ve heard my tank “click” when my stomatopods weren’t even striking anything. I could see them out in the open just watching me and hear a click noise. A click can be almost anything, a thermometer, a hermit crab’s shell hitting glass, even some fish make a noise that is similar to a mantis strike. The point is just because you hear a click doesn’t mean you have a mantis shrimp in your tank.

The tell-tale sign is broken shells. If you see your hermit or snail shells bashed in and pieces all over the place it is safe to say you have a mantis. Also if you see one (and this is usually rare), but is the most positive proof. Usually you will only see the eyes watching you from a hole. To get an idea of what you are looking for, consult pictures of these guys and get to know they’re anatomy (hint, Roy’s List). The more you learn about them, the better your chances of a successful hunt.

When do they come out in the open?

When they are hungry, or sometimes just curious. They are very curious creatures and therein lies they’re vulnerability. Stomatopods only need to eat about once/twice a week to survive and they can go even longer (a month) during a molt without eating. That being said, if you are attempting the bottle trap or are trying to lure it out using food, don’t let any meaty food particles hit the substrate. Any scraps can be foraged and taken back to the burrow to sustain the animal. When searching for food, they will make slow movements around rocks and zip back into their burrow. If nothing is found, they will do this several times before staying inside the burrow. Like Thurge said, if you know you have a mantis, remove the clean-up crew. Also any hard or soft bodied crustaceans are on the menu as well. Fish, not so much, slow bottom dwelling fish are most vulnerable. Many species will seal-up their burrow at night using small rubble and sand. However, to be sure, consult the species guide of Roy’s List or to get a handle on what species you may be dealing with. A common hitch-hiker is the mantis Neogonodactylus wennerae. Small rock dwelling species like this one are often found in reef tanks as well. In short, match where your live rock came from with the species to learn of the activity of the stomatopod. Their time of activity can lead to a better capture and a proper plan.

So how do I get this killing machine sent from Hell out of my tank?!?

First off, while having a mantis shrimp in one’s reef tank may be a little unnerving; these animals have been given an incorrect reputation within the reefing community. A common hitch-hiking mantis will NOT break the glass. There are only two species that do this and they must get large in order to produce the necessary force to break glass. These two species are Odontodactylus scyllarus and Gonodactylus chiragra . Contrary to popular belief, they do not kill on sight. The majority of your fish will be safe, the clean-up crew is where the damage is done and that is if they need to feed. Can a mantis catch a fish? Yes, but look at it from the standpoint of the mantis, why waste energy catching a fish when you can just grab a snail? Mantis shrimp also do not eat corals, nor will they damage them. The only exception is if the coral is not anchored down to a rock. The mantis will usually move the coral to block its burrow entrance, only it will be the wrong side up. So your corals are safe. At this point you must decide if it is really worth all the effort you are about to go through to get this animal out. Sometimes it is better to just leave the mantis in the tank. As crazy as it sounds, if you keep it fed and full , it won’t kill for food. “A fat mantis is a happy mantis”.
At this point if you are still convinced that a stomatopod in your tank is your worst nightmare read on.

Biological Control: Doesn’t anything eat these creatures?

Yes, but most of the time they are more destructive than the mantis in a reef tank. Puffers, Triggers, Cephalopods, Lionfish, Moray eels, all have the ability to solve your mantis problems. However, just because a trigger is in the tank doesn’t mean the mantis will be eaten; meanwhile your corals are being crushed by the trigger. Basically, biological control is a bad plan because all of the above animals can do more damage than the mantis.

Chemical Control: What about Copper?

Even small amounts of copper can kill a stomatopod. Unfortunately, Cu will also kill most of your inverts and hence isn’t a great option. If you have a fish only tank, well you’re in luck.

Getting your hands wet: Ok ok what do I gotta do?

The Bottle Trap
Thanks to Justinl for this article.

I would like to add that there are additional ways to construct a device to catch these guys. It’s truly amazing what you can do with plastic screens and zip ties. I’ve seen little chambers constructed out of just these two materials. One way is to make the trap in the shape of a heart with the opening located in the top, between the two curves. The opening should continue down to the point of the heart with just enough room for a fish to swim through. You can also put more barriers within the two halves of the heart. Simply put, the more turns and the more complicated the trap is, the better your chances of catching the mantis. In all honesty I have yet to hear of the bottle trap working. The most successful ways of catching these animals in your reef is the most direct. Get creative, the mantis sure is.

Rock Location and Removal

The best way to get rid of a mantis shrimp is to find the rock it is using as a home. Simple right? Yeah, no. The best way to tell what rock the animal is in is to watch in physically enter/leave the hole. They can burrow inside rock and underneath so the mantis can be underneath rock work as well. Another way to tell is to look for a sealed hole. You will see crushed snail shells and sand blocking a hole. If you see that it is safe to assume the mantis is using that rock as a home, remove it and place it in a bucket of saltwater for now. The following is a post from Dr. Roy Caldwell on the removal of a stomatopod from a rock cavity at this stage.

“N. bredini can survive in fresh water for several minute and often do not bail out when hit with it. These are animals that live in cavities on exposed reef flats. They encounter dessication, high temperatures and fresh water (rainstorms at low tide). In short they are extremely tolerant of nasty conditions and other organisms in your LR are likely to be damaged before the stomatopod comes out of its cavity. I have seen N. bredini survive over a day in a piece of LR left to dry on a counter.

When I have to remove an animal from a cavity, try to be another stomatopod and poke at it with a probe for several minutes until the animal gives up and flees. I usually do this with the LR in the air for a few minutes, then return it to a bucket of water with more poking. With a blunt probe and a little care, you can avoid damaging the animal. I also sometimes use a clove oil solution to anesthetize them and then remove them with forceps. (This works well in the field. For example, we perfected the technique to remove a species of stomatopod that was found in cavities in large barrel sponges found at 50-60 m. With very little bottom time, we could usually find and remove three or four on a dive.)

The one dip that seems to work to some extent is sparkling soda water. The carbonic acid may be sufficiently irritating to their soft tissues to drive them out. I've tried it a few times (I filled the cavity with selzer, let it stand for a minute or two and place the cavity back into sea water.”
- Dr. Roy Caldwell

If these techniques do not work, hammer time. Get a hammer and bash that rock in half. If you wish to safe the mantis, and please do, you can leave the mantis rock in a small container and try to entice it out with food. If it never comes out, just leave the rock in there until it does and remove the rock afterward.

What if I cannot find the rock?

Guess what, it’s time to roll up those sleeves and do what I do when moving mine. Note: This involves tearing down all the rockwork and moving it, so if this is not possible for you, well, tough luck, keep trying the bottle trap. Or you can learn to live with the mantis (it’s really not that bad). First you need to start lifting up and shaking the hell out of every rock you have, after shaking it, put it to one side of the tank. There is no guarantee that shaking the rock will remove the mantis but it always works for me. Usually the mantis will be in between the rock and the substrate so simply moving it will make it shoot out. Repeat this until you find the mantis and use a big net to corner it against the glass. Once the mantis is out in the open, quickly move all the rocks to one side and keep an eye on the mantis. DO NOT let it get to the side of the rocks. The goal is to move all the rocks to one side of the tank and keep the mantis on the other side. In cornering the mantis, slowly move the net toward it and try to distract it with another object (another net/feeding stick). Get the mantis in between the net and the glass and press the net up against the glass. This point is critical because when you start moving the net close it will most likely dart to one side or the other (emphasis on big net). And obviously make sure it is a fine threaded net, no big holes. They are very good swimmers and extremely quick when startled. Take your time. Once the mantis is up against the net and glass, just slide the net up, keeping it pressed up against the glass, until you get to the surface. Quickly lift the mantis out and place it in a container of saltwater. There you have it, you have captured a stomatopod. Now you can sell it to us! Money for your nightmare!

I would like give credit to Dr. Roy Caldwell, Justinl, Trappedmetal, Thurge, and anyone else who posted about not being able to get a mantis out. Much of the information from this post came from this forum and my memory of past experiences/posts.
Happy Hunting!

Last edited by Koshmar; 09/23/2009 at 12:54 PM.
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