Hydraenidae is a family of very small aquatic

Aquatic animal

An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that...

 beetle

Beetle

Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...

s with a worldwide distribution. These beetles are generally 1-3 mm in length (although some species reach 7 mm) with clubbed antennae

Antenna (biology)

Antennae in biology have historically been paired appendages used for sensing in arthropods. More recently, the term has also been applied to cilium structures present in most cell types of eukaryotes....

. They do not swim well and are generally found crawling in marginal vegetation. Most are phytophagous but a few saprophagous and predatory

Predation

In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...

 species are known.

The larva

Larva

A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...

e, although preferring damp habitats near water, are non-aquatic and tend to drown easily.

Subfamilies

• Subfamily Ochthebiinae
  • Gymnochthebius
  • Ochthebius
  • Micragasma
  • Neochthebius
  • Hughleechia
  • Meropathus
  • Tympanogaster
• Subfamily Hydraeninae
  • Coelometopon
  • Sicilicula
  • Prosthetops
  • Hydraenida
  • Parahydraenida
  • Parhydraena
  • Decarthrocerus
  • Mesoceration
  • Podaena
  • Homalaena
  • Orchymontia
  • Laeliana
  • Limnebius
  • Adelphydraena
  • Hydraena