Go Tiges

Well the footy season is over for Richmond AGAIN! But rest assured all you Richmond Tigers fans, there are some Tigers—Water Tigers, that is—fighting and scrapping in your local dams and billabongs. Water Tigers (Dytiscidae sp., from the Greek dytikos meaning ‘able to dive’), pictured left, are the larvae of Predaceous Diving Beetles.

Both the adult beetles and larvae eat by grasping their prey between strong pincers. The pincers are hollow, which allows the Water Tiger to inject enzymes into the victim and then suck out the juices while the prey is still alive, similar to how a Robber Fly feeds. Whereas the adult beetles can swim and catch prey, the camouflaged larvae hunt by remaining motionless on a rock or stick and then grabbing any prey that floats or swims by. Adult beetles can stay underwater for prolonged periods by trapping air between the wings and body. The larvae breathe through three snorkel-like attachments at the rear of the body (see photo).

And then there were two!

These insects are highly predaceous at all stages of development. In some aquatic environments the Water Tiger is the apex predator (has no predators itself). In the time it took me to get my camera focused for the photograph (right), two Water Tigers had already attacked and half-devoured a third individual.

It appears that pond life is just as cut-throat as footy.