Dragonfly nymphs propel themselves through the water with a miniature jet engine, taking water in below their mouths and shooting it out their back ends. You can see the ripples from the jet out this one's back in this video.
Cordulegaster Dragonfly NymphView 4 PicturesThis is a realy big, dark dragonfly nymph. Notice how "fuzzy" it is--it's covered with small hairs that collect sediment and debris and camouflage the nymph to match its natural surroundings. The greenish cast in some of the photos of this specimen is due to strange lighting during my first night photographing things for this site.
Leucrocuta hebe (Little Yellow Quill) Mayfly NymphView 4 PicturesThis is a very early instar (Instar: Many invertebrates molt through dozens of progressively larger and better-developed stages as they grow. Each of these stages is known as an instar. Hard-bodied nymphs typically molt through more instars than soft-bodied larvae.).
Epeorus vitreus (Sulphur) Mayfly NymphView 3 PicturesI suspect this is an Epeorus vitreus nymph. At the current instar (Instar: Many invertebrates molt through dozens of progressively larger and better-developed stages as they grow. Each of these stages is known as an instar. Hard-bodied nymphs typically molt through more instars than soft-bodied larvae.), it's tough to make out the pair of dots on the tergites (
One tergite of this Isonychia bicolor mayfly spinner is highlighted in red.
Tergite: The top (dorsal) part of a single segment on an insect's abdomen when it consists of a single chitinous plate (sclerite), or an individual sclerite if the segment has more than one.) which signify that species, but with zooming and contrast enhancement they become evident.
Isonychia (Slate Drakes) Mayfly NymphView 3 PicturesThis smaller Isonychia nymph was caught with a bunch of bicolor specimens, but it does not have the fluffy spine structure at the base of its gills. This might mean it's Isonychia sayi, or it might just be a bicolor nymph too young to have developed those structures.
Leucrocuta hebe (Little Yellow Quill) Mayfly NymphView 2 PicturesThis is a very early instar (Instar: Many invertebrates molt through dozens of progressively larger and better-developed stages as they grow. Each of these stages is known as an instar. Hard-bodied nymphs typically molt through more instars than soft-bodied larvae.).