Water beetle
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A water beetle is a beetle adapted for living in water. A number of different types are known, nearly all living in or on fresh water. The few marine species tend to live in the intertidal zone.
Many water beetles carry an air bubble underneath their abdomens, which both provides an air supply, and prevents water from getting into the spiracles. Others have the surface of their exoskeleton modified to form a plastron, or "physical gill", which permits direct gas exchange with the water.
Most families of water beetles have larvae that are also aquatic, but the reverse is not true; many have aquatic larvae and terrestrial adults.
Types that are aquatic in all life stages include:
- whirligig beetles (Gyrinidae)
- crawling water beetles (Haliplidae)
- burrowing water beetles (Noteridae)
- trout-stream beetles (Amphizoidae)
- predacious diving beetles (Dytiscidae)
- skiff beetles (Hydroscaphidae)
Types in which the adults are not necessarily aquatic include:
- water scavenger beetles (Hydrophilidae)
- travertine beetles (Lutrochidae)
- long-toed water beetles (Dryopidae)
- riffle beetles (Elmidae)
- forest stream beetles (Eulichadidae)
- variegated mud loving beetles (Heteroceridae)
- minute mud beetles (Limnichidae)
- water pennies (Psephenidae)
- Ptilodactylidae
- minute bog beetles (Sphaeriusidae)