Subject: What is it
Location: San Isabel national forest, Colorado
August 18, 2015 4:13 pm
I found this critter in a unnamed lake at about 12,000 ft. There was only this creature, leaches and small invertabreas that looked like minnows. Under closer inspection they were not minnows but a small swimming animal using cilia to move. I have found pictures close to this mystery animal but nothing exact. Also, was wondering if there may be a guess at what the smaller swimming creatures were too, (sorry blurry pic).
This magnificent aquatic predator is a Water Tiger, a Predaceous Diving Beetle larva, probably in the genus Dystycus based on this BugGuide image. According to BugGuide, they can be identified by the following features: “Larvae with prominent cerci and dense lateral fringes of hair on the last 2 abdominal segments and cerci. The anterior portion of the head is rounded.” We cannot make out anything in your blurry image, but we suspect the “small swimming animal using cilia to move” is a Fairy Shrimp.