Varys' babies (O. mercatoris)

4 month anniversary (7/2/08)

The Nice Animal Mother;120570 said:
Your pictures make me kinda miss Einy. I always enjoyed watching him take down fiddler crabs.

Varys' offspring turn 4 months old today! And to celebrate, I asked Tarzan to do a video re-enactment of AM's "Einy" taking down a fiddler crab! :biggrin2:
 
It looks as if the crab is reacting to the cephlotoxin in the last second where its legs seemed to shake. Did you notice if the crab died and was then eaten or if Tarzan attacked it further to cause the death? I am reading Jacques Cousteau's The Soft Intelligence (still well worth the read) and he mentions noting the use of the toxin more as "spit" than bite as Tarzan appears to do in the video.
 
dwhatley;121147 said:
It looks as if the crab is reacting to the cephlotoxin in the last second where its legs seemed to shake. Did you notice if the crab died and was then eaten or if Tarzan attacked it further to cause the death? I am reading Jacques Cousteau's The Soft Intelligence (still well worth the read) and he mentions noting the use of the toxin more as "spit" than bite as Tarzan appears to do in the video.

That's what I thought too D... and it seems to be a consistent pattern. The merc grabs the crab, bites the joint between legs and body, the crab shakes, the crab stops moving within a minute, and then the merc begins to envelope the crab with its mantle. I haven't seen anything that would indicate "spitting" cephalotoxin, but I'll keep an eye out during future feedings. Are you talking about something like the cephalotoxin coating the crab's gills?

Also, I'm assuming the dark spot visible inside Tarzan's mantle in that video is the ink sac? Or could it be something else, like the gill heart?
 
I've never heard about cephalotoxin impacting the gills... I remember Gilly mentioned that the mechanism (for a cuttle and a crab) was much like some insecticides, that causes convulsive muscular paralysis in arthropods when injected by a beak bite.

I'm also not clear on what "spit" means in this context: I believe it's produced in the salivary glands before injection, but I've never heard it "thrown" at a distance the way a cobra spits venom... Although I have heard about something in the ink that works at a distance and coats the gills of the octo's predators...
 
Cousteau is not clear on (and I don't think they were sure themselves) how the "spit" was delievered but (and remember that this is translated so the meanings could be somewhat distorted) the book clearly implies that there was no bite involved (close contact, yes, but not a beak bite). They did a lot of disection in their exploration and did say that the salivary glands produce the toxin.

When 'Tane takes a crab (rare today but originally he would not let them hit the substrate) or his shrimp it disappears into the folds underneath and you can't see anything even when he is spread on the glass. If this is common in the larger octos then they might be exposing the food to the toxin in a very contained area or they may just be sufficating it as they seem to do with each other when fighting. However, the little guys don't completely cover the food immediately (and it can always be seen). The leg reaction of the crab suggest something entered his system rapidly. It would seem that gills might be a very vunerable spot for a quick acting toxin and would not require the small beak to penetrate the shell (IME the Merc's beak can't even penetrate human skin).

gholland;121150 said:
Also, I'm assuming the dark spot visible inside Tarzan's mantle in that video is the ink sac? Or could it be something else, like the gill heart?

You are likely looking at the hearts if you are seeing the dark spots on each side of the mantle. Sometimes you can even see them pumping (particularly when the octos are white and stressed). I have seen two but I am not sure where to look for the third ;>). I wish I had a better way to photograph the details since I keep thinking that the noticable paralasis I saw in both Sisturus and Little Girl had to do with heart failure or blockage of one of those visible hearts.
 
dwhatley;121160 said:
It would seem that gills might be a very vunerable spot for a quick acting toxin and would not require the small beak to penetrate the shell (IME the Merc's beak can't even penetrate human skin).

I agree with your observation that mercs don't seem able to bite us (I do think they would if they could), but I have to wonder if that's actually because they can't break the skin or is it due to the relatively flat surface (compared to the size of the beak) that skin on a hand presents, preventing them from getting any real purchase with the beak? A relatively narrow crab leg (or the weaker membrane at the joint) would seem to be much easier to wrap a beak around to apply a bite. Of course the gills are also right there on the side where Tarzan was attached...

I watched the full-length video again... the crab starts twitching about 20 seconds after contact and then goes still at about 40 seconds.
 
I have read that octopuses look for a joint or a soft place like an eye to inject venom.

As for J. Cousteaiu's theories, that book was published in 1973(first American edition) and we have learned a lot more about cephs since that time. However, it's still an interesting book and I've included it in the reading list for our Cephalopods book.

Nancy
 
Food fight

Last night we witnessed our first "food fight". Beluga was off eating a fiddler claw that I had given him, while Tarzan and Quattro(?) (it's getting so hard to tell!) were both sitting on the same rock, closely watching a fiddler that we had just dropped in the tank. Quattro was "bobbing", clearly excited by the prospect of crab dinner, while Tarzan was obviously interested, but had dined on crab the night before.

As luck would have it, the crab practically stumbled over Tarzan and he made quick work of it, pulling it into his den. Moments later, Quattro swam up to Tarzan's den with his mantle elongated and made a "grab for the crab"! There was a quick flurry of arms, and then Quattro actually entered the den with Tarzan. A few seconds later, one of them (Quattro?) exited where Quattro had just entered and quickly crawled around to the other side of the liverock. We promptly added another fiddler to appease the "loser", but at this point, it was no longer about dinner. Quattro ignored the second crab and eventually began creeping back around the rock, only he did it down low and came up from below this time. Another flurry of arms, another entry into the den, but this time an octo came out the opposite side that one had gone in. Whoever this one was, they squirted ink and then jetted off. (Note: the ink is much less viscous now than it was when they were babies.) Shelby actually ended up getting the second crab and the "inky loser" had to settle for a hand-fed crab claw. :roflmao: It's funny now, but we were freakin' out when it happened!

I know mercs sometimes get dismissed as "boring", but we're having a ball with these 'podes!
 
Greg,
I saw that sneak attack several time with Sisturus and Medusa (usually Sisturus stalking Medusa) but I don't remember Sisturus actually entering Medusa's den. I initially thought I was seeing mating behavior but it may have been male dominance since Medusa turned out to be a male. These are the references I found doing a quick search:

Tonight, Medusa was in the live rock at the front of the tank and showed her eyes. After eating though she went back to the main rock and Sistrurus reacted quickly and they had a brief skirmish. Medusa made his/her way back into the LR and Sistrurus blocked the opening for a few seconds but did not follow. I am hoping this is a sign that he wants to mate but she is not ready rather than the possibility that they are both male. They have lived very close to each other without problems, choosing to be within arms reach until they were put into the larger tank (they still stayed close for about 2 weeks). Sistrurus' reaction was particularly surprising because he is extremely gentle. If I am seeing a mating behavior, it appears that if a male catches a female in the open, it may match the violence that Roy has seen.

I have seen Sisturus approach her and touch arm tips without any sign of aggression between them but at other times they will quickly meet beak to beak (without actually touching mouths) and seem to be squabbling. Neither turns deep red during these meetings and they are brief but it does make me nerveous. Tonight Medusa jetted across the tank in front of Sisturus and took a very aggressive (possibly defensive) position. She held two of her arms very rigidly out from her body (not the typical arms up between the eyes pose) and made a quivering motion with them. The whole length of the arm was in a tight motion, not just the tips like in the video that gave Sisturus his name. She did not attack but look ready to take on a ninja.

He is more interactive with Medusa and the contact is less aggressive. I have seen her reach out to touch him when he is doing his wall climbing and sometimes they tussle for a second or two but not violently and no one is missing arm tips or has sustained any damage. I don't know if this is courting behavior or just two octopuses reaching maturity in a small tank. Tonight they were both in the same barnacle cluster and when I sat in front of the tank both came out at about the same time. Sisty covered Medusa's shell, quivered and then arched over the opening for a maybe a minute but there was no biting and no arm reaching into the shell.
 
A while back, I started noticing that the 'podes came out much faster, and more completely when the tank was dark than when the red filter was on the light. I recently bought another sheet of red vellum with the hopes of dimming the light level still further. It seems to have made a significant difference. I now see more of them and I see them sooner than ever before. I think we now have 4 layers of vellum and 2 layers of red acetate film over a standard fluorescent light at night?

The color of my shirt seems to be somewhat important too. If I wear a light shirt, they see me coming and withdraw into their dens for a while, but eventually come back out while I'm there. If I wear a dark shirt, they rarely withdraw when I approach. Either way, they don't seem to mind me being there once they realize who/what I am? I can stick my face right up to the glass where they are attached with no fear.

I keep trying to catch sight of a hectocotylus or enlarged sucker, but so far I haven't seen anything.

I did have some fun with Beluga at 4:30 am one morning when I woke up and couldn't go back to sleep... Beluga was staring out of the hole in his/her rock as usual and did a little head-bob when I brought my face close to the glass. I bobbed back. Beluga bobbed again. I bobbed again. Then I put my finger up to the glass and made very slow and short stroking motions. Beluga slowly reached out about 2 inches and put a tentacle up to the glass when I was touching it. (D, didn't Trapper do this with you regularly?) The "contact" only lasted a few seconds, but it was very cool to interact from outside the tank like this!

Krill doesn't seem to be a popular food item, despite the 'podes reputation as "the little piglets that will eat anything". :wink: Here's a pick of Quattro (about half the size of the others, but growing) after he discarded the krill and stole the bamboo skewer. Tarzan ate on the krill for a short while, but not much.
 
(D, didn't Trapper do this with you regularly?) The "contact" only lasted a few seconds, but it was very cool to interact from outside the tank like this!

Yep! After she took her barnacle den, she would do an "ET touch" on the glass (acrylic). She would only do it once but would repeat the action nightly.

I have found that s-l-o-w-l-y stoking the glass seems to be a positive way to interact with many of the tank critters. Some of my seahorses would come and dance with my finger when they were young (after they were full adults, however, the interaction was minimal). Unfortunately, my male mandarin does not respond this way but his mate did before he joined her. Octane will (sometimes)follow my finger arund the tank even though I interact in-tank with him daily.

I can't decide if the taking of the feeding stick/pipette is a defensive move or just an entertainment. I have not read of an octopus inking when they do this but when mine have taken the feeding tool, they were in pissy moods (Octane has only done this once the whole time he has been with us). Medusa started taking the pipette regularly afer Sisturus died but not before so I am not sure what the behavior signifies. Most people report that they feel the octopus is playing and perhaps Medusa was lonely and trying to interact.
 

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