A water tiger, the diving beetle in it's larval form, attack a large dragonfly nymph, Danube Delta, Romania. Photographed at night. The flat and square head is equipped with a strong pair of large pincers. Their usual prey includes tadpoles.
Dytiscidae are a family of water beetles. They have short, but sharp mandibles. Immediately upon biting they deliver digestive enzymes. The larvae are commonly known as water tigers. The family has not been comprehensively cataloged since 1920, but is estimated to include about 4 000 species in over 160 genera.