Nano Tank

I spent a good portion of the afternoon yesterday with my hands in our marine tank due to issues caused by a new resident. Last weekend we added three new critters to our tank which, until now only contained live rock and soft corals. Actually, we did have Mr Whippy the hermit crab but sadly he died for reasons unknown after only 2 weeks in the tank. We think he wasn’t quite right from the start as he never moved around much and spent all day every day sleeping, until that one particular night when he pulled himself out of his shell and dumped himself on the substrate to be eaten by the bristleworms. I came down in the morning to find a pile of inedible legs and his shell laying on the gravel. Sad times.

The new residents are facinating. First off we bought another Hermit Crab. He’s a bit different from the last one, not as attractive and slightly disabled yet at some point during the day he wakes up and goes for a wander to turn over the substrate in search of food before returning to the same rock under the toadstool coral to sleep. His legs are an orangey brown colour and I’m not sure but I think he may be missing an extra leg on each side as he only has two skinny little legs that pull him around and two pincer claws at the front which he uses to pick through the sand and eat. The pincer claws are what got him his name, with one being very large and the second being much smaller we decided to name him Jeremy Beadle (a late British TV presenter who, due to Poland Syndrome, had one had smaller than the other).

The other two new residents are a pair, a Yellow Watchman Goby fish and a Pistol Shrimp. The deal with these two are that they form a ‘symbiotic pair’ which is a pairing of two different species. The shrimp digs a burrow in which the fish lives and in return for the shelter the fish protects the shrimp – whom is blind.

Watching Valentino (the shrimp) and Rossi (the fish) live together is facinating in that Valentino is like the super busy tidy freak – or your mum busily trying to vacuum under your feet while you slob on the couch. And Rossi is like a fat lazy teenager who hangs around in one spot looking out for food all day. Where ever Rossi sits, Valentino is never far behind shovelling arm loads of substrate out of the way to provide a better more spacious cave for them both to hide in. If Rossi gets in the way I’ve seen Valentino shovelling him  out of the way too.  The whole time Valentino is working Rossi sits at the entrance of the cave keeping an eye out for food and predators – or us, walking into the room. Rossi warns Valentino either by a specific twitch which Valentino feels by keeping his long antennae rested on Rossi’s back or simply by getting crammed head-on back into the cave as Rossi makes his lightening fast duck for cover!

Valentino is like a minature bulldozer. Shaped like a dwarf lobster he has two longer arms at the front with pincers on the end. One pincer is larger than the other and together these arms are capable of shovelling and holding about half a teaspoon of substrate! He spends all day every day bulldozing mounds of gravel from underneath the rocks creating a maze of interlinked caverns beneath. And therein lay the reason for my arm bath yesterday – within an hour of introducing them to the tank, Valentino had already shovelled so much gravel from under the reef that part of it collapsed in the middle! Worried that he would eventually set to work on the rest of it I had to reach in and rearrange the rock so it sat flat on the tank floor with no gravel underneath it.

Fortuantely the rearrangement has worked out really well providing much more space for new corals and even bigger areas for Valentino to safely clear out creating their new network of caves that has at least four exits from which he and Rossi sit viewing the tank floor and grabbing the occasional brine shrimp that floats past.

Valentino’s talents don’t stop there. Being blind I guess hunting food can be a bit tricky so these aptly named ‘Pistol Shrimp’ posses an awesome ability in thier larger claw which doubles as a mini gun.

Routinely throughout the day and evening you can hear a loud CLICK coming from the tank, this is Valentino shooting his prey. With one clamping shut of his larger claw he can create a shot of air that fires through the water at over 60mph.  When the air bubble bursts it results in the loud click that we hear. I’ve also read that when the bubble bursts it emits a flash of light (not visible to the naked eye). This flash has a temperature of over 8,000 degrees farenheight, the temperature of the sun! The force and sound eminating from this deadly claw stuns the shrimps prey so he can eat it. How does it find the prey in the first place? I guess it’s by vibrations in the water.

Here is a little video of Jeremy Beadle asleep under his toadstool, Rossi ‘watching’ and Valentino bargeing in and out of the cave with arm loads of substrate gravel.



  1. Redhead said

    Busy little fellow, isn’t he!

  2. Foxsden said

    Yer… wish I had some of his enthusiasm to get off my ass and do my housework!

  3. Tilly said

    LOVE that. Also love that Eels track, haven’t heard it for ages.

    You should totally set up a webcam, so we can check out your fish tank all the time – you can even watch it from work! Seriously.

  4. Foxsden said

    I love the way the shrimp marches out of the cave and lifts the fish up over his head when he’s in the way! Cracks me up.

    The problem I’ve got with a webcam is that the tank is 3 rooms away from the computer!… would need a very long cable..

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