Tadpole Shrimp at Swimming Hole

Observation: This was found in our swimming place yesterday I think. This is a lake where people like to swim in the summer and it was pretty warm with temperatures in the high 70s. The girl that took the picture said there are hundreds more by the shore line. People are concerned and wanna know what this is. If you have any info. please let us know ASAP so I can let everyone know. All freakin' out. Sharon Kozevnikoff

LEO says: This observation was forwarded to the Institute of Ocean Sciences in Sydney BC, Canada. Based on the consultation it may be a tadpole shrimp (Lepidurus arcticus)), mainly a scavenger that feeds of the sediment. It is not thought to pose any hazard to people. Moira writes:

Institute of Ocean Sciences Consult: Moira Galbraith, a Zooplankton Taxonomist, writes "It looks like a branchiopod but need to see more of the animal to make out all of the features. It appears to have a large cephalon with eye spots? Notostraca: Triops or Lepidurus, the telson structure is more like Lepidurus. These animals can get anywhere from 2cm to 10cm long, considered to be living fossils and are found worldwide in saline pools and brackish water. I would need more pictures of appendages or a specimen to confirm identification. Apparently these are rare, occurring episodically, usually found in ponds and shallow lakes so the reference to the river is interesting. They appear to be primarily epibenthic in nature but will swim to capture Daphnia and copepods. Warmer water leads to more of them but I think it is unusual for them to be in the river unless it was a back water area."

For more on the topic, Dan Rinella from the Environmental and Natural Resources Institute (ENRI)) at UAA recommends Revision of the NE Arctic Lepidrus (Notostraca) by D Christoper Rogers, in the Journal or Crusteacean Biology.

LEO says Thank you Moira for your assistance and also thank you to Tom Okey, Bruce Wright, Sonia Batten, Kris Holdreid and Dan Rinella.

Note: see also post on August 27, 2013, Circumpolar Climate Events Map, entitled Living fossil found in Enontekiö).