In the water-beetle, the structure of its legs, so well adapted for diving, allows it to compete with other aquatic insects, to hunt for its own prey, and to escape serving as prey to other animals.
Uretako kakarraldoaren kasuan, bere hanka urpetik ibiltzeko hain ongi moldatuen egiturak, beste uretako intsektuekin lehian ihardun, harrapakinak eskuratu eta beste animalien harrapakin izatetik ihes egiteko modua eskaintzen dio.