whirligig beetle

Whirligig beetle
Gyrinus natator
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Coleoptera
Suborder:	Adephaga
Family:	Gyrinidae Latreille, 1802
Genera
Andogyrus Aulonogyrus Dineutus Enhydrus Gyretes Gyrinus Heterogyrus Macrogyrus Metagyrinus Orectochilus Orectogyrus Porrorhynchus Spanglerogyrus

Wikispecies has information related to: Gyrinidae

The whirligig beetles are a family (Gyrinidae) of water beetles that normally live on the surface of the water. They get their common name from their habit of swimming rapidly in circles when alarmed, and are also notable for their divided eyes which can see both above and below water.

They are also known for their grouping behavior, a survival mechanism which helps them to avoid predation. Their places in the group are thought to be determined by a number of factors, including hunger, sex, species, water temperature, age, parasite level and stress level. Research being done on their behavior serves as a model to study the significance of chemical defense in relation to their position in the group, which relates to such fields as nanotechnology because the beetle's motion provides insight into the way in which groups of robots might coordinate movements.^{[citation needed]}

This article may be confusing or unclear to readers. Please help clarify the article; suggestions may be found on the talk page. (November 2007)

Specifically, the beetles make behavioral trade-offs which lead them to different group positions. For example, relatively hungry beetles go to the outside of a group, where there is more food but higher risk of predators. Males are also more likely to be found on the outside of groups (although grouping is unrelated to mating behavior in this family). Individuals swimming against the flow of water in a stream incorporate the needs of drafting into these group positioning decisions. Drafting is when animals swim behind others to take advantage of forward-moving drafts. The determination of forward/backward positioning within a group has been found to be a complex function relating to the: speed of the water, the sex of the beetle, and the type of predator (bird or fish) most recently observed by a beetle.

They have a bubble of air trapped underneath their abdomens which allows them to dive and swim under the water for a long time. The family includes about 700 species worldwide.

Larva and Adult

Hind leg of Gyrinus

Antenna of Gyrinus

References

• Ross H. Arnett, Jr. & Michael C. Thomas (2001). American Beetles. CRC Press. 

• William L. Romey (1995). "Temperature and hunger alter grouping trade-offs in whirligig beetles". The American Midland Naturalist 134: 51–62. doi:10.2307/2426482. 

• William L. Romey (1995). "Position preferences within groups: do whirligigs select positions which balance feeding opportunities with predator avoidance?". Behavioral Ecology and Sociobiology 37: 195-200. 

• William L. Romey & Abigail C. Wallace (2007). "Sex and the selfish herd: sexual segregation within nonmating whirligig groups". Behavioral Ecology 18: 910-915. 

• William L. Romey & Emily Galbraith (2008). "Optimal group positioning after a predator attack: the influence of speed, sex, and satiation within mobile whirligig swarms". Behavioral Ecology 19: 338-343. gytr