E-Fauna Photo Gallery
© Ian Gardiner (Photo ID #17313)
Photographer's Submitted Details
Wapiti Lake, nr Jaffray, BC
July 08, 2012
UTM Zone #
Photo ID #
Blue form. Length ~15mm. Collected 03 Jun 2012. In a study by Hindsbo, it was found that 100% of blue Gammarus lacustris (5% of the sample studied) were infected with the final larval stage of the parasitic worm Polymorphus sp. It was demonstrated that this parasite affects both the colour and behaviour of Gammarus, making it more susceptible to predation by Polymorphus' final hosts - waterbirds. The blue colour is caused by the intake of carotenoids by Polymorphus from their intermediate hosts. Polymorphus can be seen as the bright orange spot under the colourless cuticle. Location coordinates have been offset by up to 5km.