Fluid Propulsion in Dragonfly Nymphs

  Immature dragonflies (nymph stages) are aquatic. The rectal chamber of dragonfly nymphs is highly specialized for respiration. By contracting abdominal muscles, water is pumped in and out of the rectal chamber.  The chamber thus functions as a gill.
   1) In what aquatic habitats would you expect to find dragonfly nymphs?
   2) What do dragonfly nymphs eat?
  
3)  What features of the adult dragonfly are developing on the dorsal surface of the thorax and abdomen of this nymph? 
   4) What is the main form of locomotion in adult dragonflies?



When dragonfly nymphs are disturbed or attacked, rapid contraction of abdominal muscles can forcefully and rapidly eject water out of the rectal chamber and anus, as shown in the two animations at the far right.  Thus, forward locomotion in these cases is achieved by fluid propulsion.

   5) What other forms of locomotion exist in dragonfly nymphs?
   6) What other invertebrates use fluid propulsion to move?