The
Dytiscidae – based on the Greek
dytikos (δυτικός), "able to dive" – are the
predaceous diving beetles, a
family of
water beetles. They are about 25 mm (1.0 in) long on average, though much variation is seen between
species.
Dytiscus latissimus, the largest, can grow to 45 mm long. Most are dark brown, blackish, or dark
olive in color with golden highlights in some
subfamilies. 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.