Copepod... Or Mantis Fry?

[smithrc]

I was quite happy with the ammout of copepods walking the tank until I started to notice that there are now a lot that are 2-3mm in size....
That and the fact that they are looking different to what I had been expecting...
I've had a look on google and cant find any copepod pictures that look like these.

They have large pincers at the front, tucked under their body... and the flick them at each other... reminisent of a mantis shrimp...

someone put my mind at rest and tell me I'm wrong please

 

[SkiFletch]

Well those pics arent the clearest... Do they look like this amphipod?

Or perhaps like this isopod?

Shots courtesy of melevsreef.com

 

[Mr Miagi]

Look like an isopod to me. Dont be surprised if you get large pods though, take a look at my largest specimen! He was found in the bottum of my canister filter!

 

[nmonks]

Looks like some kind of isopod to me, too.

Mantis larvae are planktonic and very distinctive (huge stalked eyes relative to body size, a large body segment, and a thin, scrawny abdomen). Once metamorphosed into the bottom-dwelling form, they all look pretty similar regardless of size. The tail "plate" for example is invariably a solid plate with perhaps some knobs and spines but never long "feelers" like those seem to.

Another good clue to a mantis shrimp is they relatively few walking legs, I think only ever six. Behind them are reduced swimming leg / gill things rather like flaps, neatly tucked underneat the body and certainly not sticking out the side when viewed from above. Only on either side of the tail "plate" will there be paddle-like legs.

There are lots of crustaceans with mean-looking pincers that are actually quite harmless. Often, these are no pincers at all. Corophium, for example, has huge claws, but they're used for digging. Snapping shrimps use their giant claws to produce sound (which makes them great fun pets, if a bit unsettlingly noisy). Male fiddler crabs use them in ritual displays and for wrestling matches over females and territorial disputes.

Cheers,

Neale

 

[smithrc]

Isopod it is - phew