Larvae of the mayfly family Ephemeridae have large, distinct mandibular tusks projecting forward from the head, used to help burrow in soft silty sand or marl along the edges of still-water habitats or along the quiet parts of streams. They react negatively to light and immediately burrow back into the sediment if removed. Larvae also have feathery gills along the abdomen, giving them a rather “fluffy” appearance from the dorsal side. They are able to undulate these gills in order to increase flow of water for oxygen intake, which is especially important in the burrows where there is little water flow. The adults of this group are popular for fly-fishing enthusiasts because they are relatively large, and the duns (flying subadults) emerge in large numbers. The larvae are also sometimes used as bait.
Wings developing in wing pads. Mouthparts suitable for chewing. Gills present on tops and sides of abdomen. Segmented legs present. One tarsal claw per leg. Usually with 3 tails (sometimes 2).
Family:Large tusks project forward anteriorly from the face and are visible dorsally, when viewed laterally they curve upward. Foretibiae are fossorial (modified for burrowing: expanded or with tubercles). Ventralapex of each hind tibia acutely pointed. Abdominal gills on segments 2–7 are conspicuous dorsally, forked and elongate-lancolate, with fringed margins, giving the animal a fluffy appearance.
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