Does anybody have any experience with mantis shrimp in the tank with an octo? My little fella has about a 1" mantle & 2" arms, would he be able to handle a 2.5 - 3" mantis? ive heard the mantis are quite aggressive.
Dr Roy Caldwell is your guy for this (being ver knowledgable in both mantis and cephs), but i fear that the octo may eventually make a meal out of the mantis. On the flip side, if the octo is small the mantis may hurt the octo.
It all depends on size. Stomatopods are common part of octopus diets, but large stomatopods also will feed on octopus. I've looked at this a bit in blue-rings and an H. lunulata will kill and partially eat a stomatopod roughly its own size, but there are species of stomatopod that will kill and eat blue-rings if they are about have the size of the stomatopod.
Many smashing gonodactylids when they see an octopus coming try to get into the open and attack aiming at the head. In one of Hall's films there is a great shot of a Hemisquilla attacking a large BiMac and in one of the Mimic films their is a sequence of a large lysiosquillid swimming up into the water column pursuing a mimic.
The bottom line is that if the octopus and stomatopod are vary different in size, the smaller one will probably become lunch. It they are close to the same size, it will depend on the species and other factors, but it is unlikely that they will coexist for very long.
Woah, lesson learned: Mantis and octos don't go well together. Mantis are just plain aggresive if you ask me, I went diving with a older buddy once and he was trying to spear a mantis with his titanium diving knife, the mantis sorta turned around and used the arm club, thing and hit the knifing knife, resulting in a sudden "CLANG!" and a very suprized diver backing away.
Several years ago a local importer received a large (4 cm mantle length) Hapalochlaena lunulata. It was the first one I had seen for sale and I bought it paying way too much even by today's prices. For a few days I photographed the female and then decided to try to get a photo of her killing a stomatopod. I had a spare Gonodactylus smithii that was brightly colored and contrasted nicely to the octopus, so I prepared to sacrifice her to the photography gods. The stomatopod was about 5 cm long, but smaller by weight and bulk than the blue-ring. I waited until the octopus was nicely positioned in front of a piece of coralline algae and released the stomatopod. Both froze staring at one another. Then the octopus started to bob up and down (range-finding), raised up slightly and started to change color - all behaviors that I now know indicate that she was preparing to attack. Suddenly the stomatpod lunged forward launching a double strike that hit the blue-ring right between the eyes driving the dactyl spikes deep into the blue-ring's brain. Death was instant. The octopus never moved again. Worse yet, it happened so quickly I never even got off the shot.
A high school friend of mine did an internship sorting whale stomach contents (and I'm only starting to realize now what she was going through ) - I think they were sperm whales, but am not sure. Anyway she invariably found, amongst the ceph beaks, the remains of one (and only one) mantis shrimp in most stomachs. We wondered whether the whales might have seriously wised up after one accidental ingestion (and I would hate to think of the condition of the mouth and esophagus afterward), or whether the ingestion of that single mantis shrimp could have contributed in some way to the stomach contents winding up on my friend's desk.
Well, I never saw the remains personally (great story if she made it all up though ) so I don't know what shape they were in, or whether you could tell anything about the condition of the animal when it was ingested. But... what's the likelihood of several separate whales each scavenging one dead, but still recognizeable, mantis shrimp?