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amphipod tiff spotted edit colour_filtered unsharpen_filtered by ernie.cooper, on Flickr

It has been waaaaay too long since I posted any photos. Funny how life can speed-up and suck all your time—especially over Christmas holidays when you have kids! Anyhow, I’m back and after a 2-week hiatus I have finally posted some photos on my blog of freshwater amphipods (that I took last summer). The photo above is of a very pretty specimen of Gammarus lacustris; apparently the only species of freshwater gammarid amphipod found in British Columbia.

Whenever (and wherever) I have collected freshwater Gammarus in the past, they have been coloured drab shades of brown and olive green. But as you can see, the specimens I collected from this particular stream showed some real diversity in colouration, including some really pretty specimens with bright red spots on a translucent yellowish body. Others had a single very obvious bright red spot on their side. I still don’t know if the spot was on the critter’s exoskeleton or was something inside the body…


amphipod red spot sharpened copyright ernie cooper_filtered by ernie.cooper, on Flickr

I really need to get back to that stream again this summer to collect more of these critters and do a better job of photographing them…

Cheers,
EC
www.macrocritters.wordpress.com

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The red spot is the young stage of an acanthocephalan parasite (probably Polymorphus). It alters the shrimp's behaviour so that it is more likely to be eaten by a bird which is the primary host of the acanthocephalan.

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Thank you very much for this! I’ve been reading-up on the topic and it is fascinating. Now I am especially keen to get back to that stream this fall and see if I can find more infected specimens. Hopefully I’ll be able to dissect out a specimen to have a look at (and maybe photograph) under the microscope. I’ll definitely need to lay off the coffee that day!

Cheers,
EC
www.macrocritters.wordpress.com