Adephaga

Adephaga is a suborder of beetles (order Coleoptera) that comprises many predatory lineages and includes both terrestrial and aquatic forms. Along with Polyphaga, it represents one of the two major divisions of beetles. A defining morphological feature is that the hind coxae divide the first abdominal ventrite, a condition used to separate Adephaga from Polyphaga in many classifications.

The suborder is commonly divided into two informal groups: Geadephaga, which includes terrestrial, predatory beetles such as ground beetles and tiger beetles; and Hydradephaga, which includes aquatic or semi-aquatic predators such as diving beetles, whirligig beetles, crawling water beetles, and burrowing water beetles. This grouping reflects major ecological differences within Adephaga.

Representative families within Adephaga include Carabidae (ground beetles) and Dytiscidae (diving beetles), as well as Gyrinidae (whirligig beetles), Haliplidae (crawling water beetles), and Noteridae (burrowing water beetles). The tiger beetles are often treated as the subfamily Cicindelinae within Carabidae, though some classifications place Cicindelidae as a separate family.

Ecology and life history in Adephaga are characterized by predation, with adaptations ranging from agile terrestrial hunters to streamlined aquatic predators. The diversity of habitats ranges from soils and leaf litter to ponds and streams. Taxonomic placement of some groups, such as Cicindelidae, varies among authorities as phylogenetic understanding evolves.