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Weird Mantis Shrimp behaviour

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Has anyone ever seen this behaviour before? I filmed it pre-dawn at Mabul, Malaysia. The spear mantis was in amongst some anchovies so I thought it might have been trying to hunt them but I never saw it go for one.... any ideas?!

 

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Has anyone ever seen this behaviour before? I filmed it pre-dawn at Mabul, Malaysia. The spear mantis was in amongst some anchovies so I thought it might have been trying to hunt them but I never saw it go for one.... any ideas?!

 

I think he was just doing his morning keep fit exercises.

 

Stew

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Wild!

 

Someone here at the museum kept a stomatopod. When live food was put into the tank it would dash out of its burrow, grab the food, somersault & dash back. It never did anything like this.

 

I linked to this thread in the mantis shrimp forum on Reefcentral. Hopefully someone there will check this out & have an answer for you.

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How cool is that! Who said Shrimp don't know how to have a good time? :)

 

Cheers,

Jim.

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Wild!

 

Someone here at the museum kept a stomatopod. When live food was put into the tank it would dash out of its burrow, grab the food, somersault & dash back. It never did anything like this.

 

I linked to this thread in the mantis shrimp forum on Reefcentral. Hopefully someone there will check this out & have an answer for you.

 

Thanks Leslie, I'm sure it must be some hunting technique to cope with moving schools of fish but I'd love to hear from someone who's seen it as well. I've seen them do a single somersault when digging out burrows but only once have I seen one go crazy like this.

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Hey Roger --

 

Dr. Roy Caldwell, THE top stomatopod expert, runs the mantis forum at RC. I was hoping he would reply and he did: "The animal is disoriented by the light. Stomatopods don't have gravity receptors and rely on a doral light reflex to tell which way is up. The lights being used to film probably moving as well as bouncing off the sand confusing the Lysiosquillina. The fish have nothing to do with this behavior."

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In 2008 at Lembeh, a mantis shrimp was observed to do similar weird and crazy behavior for at least 10-15 minutes while we watched swim crazily all over. It was also a spearer mantis, and we noted that not only did the shrimp swim up into the water column repeatedly, did circles and other strange movements, but it also was seen to scrape it's tail shell on the sand repetitively.

 

I have only still images of the behavior, but a friend did take video, but the shrimp did some of the maneuvers seen in the video in the OP. The dive managers and dive guide from Lembeh Resort who were present on the dive said they had never seen a shrimp do this before.

 

I thought I saw something on the back of the tail and so took some close ups of the area. There seems to be a reddish blob on the tail area.

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I sent Dr. Caldwell a PM, asking him to take a look.

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Interesting reply complete with id --

"Thanks. The species in the photos is Acanthosquilla multifasciata, a fairly common stomatopod that lives in sand burrows. The red color are the ovaries packed with eggs visible through the transparent cuticle. If you look at the first photo with the female on her back, you can see some white bands on her thorax. These are cement glands that only develop when the female is ready to lay her eggs. They provide the cement that holds the egg mass together. This species almost never leaves its burrow and is quite clumsy on the surface. I suspect she was disoriented and was trying to make a swimming escape, although another possibility is that she was distressed by a failed attempt to lay her eggs. When something goes wrong physiologically, stomatopods often leave their burrows. Again, thanks for showing me the photos. It is rare to see the species - especially a gravid female."

 

The white bands that he refers to are the 3 bands that stretch between the 3 pairs of legs. To me the clump of eggs on her back supports the idea of a failed attempt to lay her eggs.

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Interesting reply complete with id --

"Thanks. The species in the photos is Acanthosquilla multifasciata, a fairly common stomatopod that lives in sand burrows. The red color are the ovaries packed with eggs visible through the transparent cuticle. If you look at the first photo with the female on her back, you can see some white bands on her thorax. These are cement glands that only develop when the female is ready to lay her eggs. They provide the cement that holds the egg mass together. This species almost never leaves its burrow and is quite clumsy on the surface. I suspect she was disoriented and was trying to make a swimming escape, although another possibility is that she was distressed by a failed attempt to lay her eggs. When something goes wrong physiologically, stomatopods often leave their burrows. Again, thanks for showing me the photos. It is rare to see the species - especially a gravid female."

 

The white bands that he refers to are the 3 bands that stretch between the 3 pairs of legs. To me the clump of eggs on her back supports the idea of a failed attempt to lay her eggs.

 

Wow!

Thanks for the info. We had no idea what that red blob was, nor that the shrimp had eggs.

While I have seen the peacock mantis holding the eggs, have not ever seen eggs before on the "spearer" variety of mantis shrimp.

Does anyone know if they lay eggs or carry them around like the "smashers", too?

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According to the Australian Museum's stomatopod page, species either carry them around like the peacock or cement to the wall of their burrows

http://crustacea.net/crustace/stomatopoda/index.htm

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FWIW, whilst I locate my wife's video of this, here's my images of the same event in Lembeh in 2008 - not significantly different to Robin's. I couldn't work out how to insert the images, so just links for now (sorry):

 

http://www.flickr.com/photos/markatwell/3197881732/

http://www.flickr.com/photos/markatwell/3197035909/

 

Thank you for settling this! Robin and I were still 'heatedly' discussing it in Lembeh last week - July 2010! I thought it was struggling to slough its shell, and Robin thought it was 'crazed' by a parasite. At least honour has been served - we were both wrong! :unsure:)

 

Mark

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Hey Roger --

 

Dr. Roy Caldwell, THE top stomatopod expert, runs the mantis forum at RC. I was hoping he would reply and he did: "The animal is disoriented by the light. Stomatopods don't have gravity receptors and rely on a doral light reflex to tell which way is up. The lights being used to film probably moving as well as bouncing off the sand confusing the Lysiosquillina. The fish have nothing to do with this behavior."

 

Thanks Leslie

 

I could swear that it was already doing this behaviour when I came upon it and I've certainly shined lights at many mantis shrimp in the past without that sort of thing happening.. BUT.. it was a long time ago! Sounds like Dr Roy knows what he's talking about so I'll take that as gospel. Thanks very much for following up Leslie, much appreciated :unsure:

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I watched a giant mantis do this while night diving the south shore of New Britain Island, PNG. It followed us for quite a while doing these somersaults. It did it even without direct light on it. It just kept following, getting quite close at times. It was a bit unsettling, as it was huge and it was not clear if it was being aggressive or not. We would turn off our lights and move away, only to find it still with us when the lights came back on.

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FWIW, whilst I locate my wife's video of this, here's my images of the same event in Lembeh in 2008 - not significantly different to Robin's. I couldn't work out how to insert the images, so just links for now (sorry):

 

http://www.flickr.com/photos/markatwell/3197881732/

http://www.flickr.com/photos/markatwell/3197035909/

 

Thank you for settling this! Robin and I were still 'heatedly' discussing it in Lembeh last week - July 2010! I thought it was struggling to slough its shell, and Robin thought it was 'crazed' by a parasite. At least honour has been served - we were both wrong! ;) )

 

Mark

 

I would be nice if you/Dana could dig through the video and post a small clip of the crazed animal.... :unsure:

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Here's a link to the video:

 

IIRC - with some confidence - the shrimp was already behaving weirdly as we arrived - i.e. no light causing it to start behaving weirdly. As you'll also see, it was covering quite some distance - including up in to the water-column.

 

Mark and Dana (who took the video)

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Before the lights came on? I'll pass the info onto Dr. Caldwell.

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Here's a link to the video:

 

IIRC - with some confidence - the shrimp was already behaving weirdly as we arrived - i.e. no light causing it to start behaving weirdly. As you'll also see, it was covering quite some distance - including up in to the water-column.

 

Mark and Dana (who took the video)

 

We noticed it because of the weird swimming around behavior, and it was in the daytime too.

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Here's a link to the video:

 

IIRC - with some confidence - the shrimp was already behaving weirdly as we arrived - i.e. no light causing it to start behaving weirdly. As you'll also see, it was covering quite some distance - including up in to the water-column.

 

Mark and Dana (who took the video)

 

It's great that you've seen this as well... I guess it rules out hunting as your mantis is not anywhere near prey. I'll be interested to see what Dr Caldwell comes back with.

 

Roger

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