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Crab breaking mussel shell

 
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nrp



Joined: 20 Nov 2005
Posts: 10
Location: Anstruther, Fife

PostPosted: Mon Dec 05, 2005 6:33 pm    Post subject: Crab breaking mussel shell Reply with quote

I've got some mussels in my aquarium. I planned to crack one open from time to time as food for the other inhabitants.

I went for the first one today and found that something had beaten me to it. The shell halves were separated. One half was in pieces. It was picked clean. I know it

was alive yesterday because I watched it belay itself to the glass.

There are starfish and shore crabs in the tank. I imagine a starfish would not break the shell,

and would take some time to finish eating it, so I suspect the crab is guilty. But I wasn't sure a crab would be strong enough to do this. The mussel was about 2 cm

long, the crab about 3 cm broad.

Any opinion?

Also - does this mean my aquarium is now self-feeding? That would be nice. I would not have to take it

with me when I go on holiday.
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bethany
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Joined: 28 Feb 2005
Posts: 19
Location: Nearwater

PostPosted: Tue Dec 06, 2005 12:46 am    Post subject: Reply with quote

Poor mussels, they are prey for number of preditors. So yes, as in the wild, the crabs and starfish will wittle away at your stock of mussels...

good to have them in the tank - as you've discovered.

There are a few topics on this, in this forum. One

here:
http://www.seashoreantics.com/forum/viewtopic.php?t=10

On the website (and even better on the SeaShoreAntics CD, it shows a two hour effort for a

common crab to scissor open the shell) Not crack it though - the edibles usually do that.

Starfish insert their stomach and eat them alive in their shells. Ther's

another topic on that in here as well - and a cut away demo on the website.
http://www.seashoreantics.com/forum/viewtopic.php?t=26

Lifes a matter of

survival on the seashore - it aint no pic-nic Cool
Good to say the sizes, like you mentioned, that is always useful and proper info to dish out with written

info.

Bethany
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nrp



Joined: 20 Nov 2005
Posts: 10
Location: Anstruther, Fife

PostPosted: Tue Dec 06, 2005 6:46 pm    Post subject: Reply with quote

This probably explains why mussels are so hard to find. I searched several places before a man told me where to look - right in the middle of a

burn that flows into the sea, about 50 m out from the high water mark.

I was puzzled by this but I guess the mussels can close themselves up to resist the fresh

water from the burn, and the fresh water will keep crabs and starfish away. Plus the mussels'll get suspended matter from the burn water. I'll look in other fresh water

outflows to see if this hypothesis holds up.

Meanwhile, another mussel has gone, this time to a starfish. It's mayhem in this fish tank! It's kind of weird how the

starfish, with no obvious centre of intelligence, was able to pick out the smallest mussel in the cluster. This kind of thing makes me think that if we ever meet intelligent

aliens, we won't have the slightest chance of communicating with them - they'll just be too alien. Heck, we can't even communicate with each other half the time.

Smile
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bethany
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Joined: 28 Feb 2005
Posts: 19
Location: Nearwater

PostPosted: Wed Dec 07, 2005 5:31 am    Post subject: Reply with quote

Mussels will survive:
where they can sufficiently feed
where they can sufficiently attach to substrate
where they can reproduce faster or

equal to the rate of predation

Around the UK there are places (often close) where populations are sparse and then there will be places where there are huge

numbers.............. all due to the above reasons.

Meyhem in your tank - indeed! It's meyhem in the wild also. Our first ever experiment/observation was ''what

ate what''!
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