whirligig beetle

　

WordNet

1. aquatic beetle that circles rapidly on the water surface
2. fly or go in a manner resembling a beetle; "He beetled up the staircase"; "They beetled off home"
3. insect having biting mouthparts and front wings modified to form horny covers overlying the membranous rear wings
4. jutting or overhanging; "beetle brows" (同)beetling
5. beat with a beetle
6. biennial Eurasian plant usually having a swollen edible root; widely cultivated as a food crop (同)common beet, Beta_vulgaris
7. round red root vegetable (同)beetroot
8. whirl or spin like a whirligig

PrepTutorEJDIC

1. 甲虫,カブトムシ;(一般に)甲虫に似た虫類(ゴキブリなど)
2. (木製の)大づち,かけや,布打ち用のつち,すりこぎ,きね / (大づちで)…'を'打ち込む
3. 〈まゆ,がけなどが〉出っぱっている,突き出る / 出っぱっている;(特にまゆ毛が)突き出ている
4. 〈C〉《しばしば複数形》(野菜サラダなどに用いる)赤かぶ,サンゴジュナ(red beet)(葉・根ともに食用) / 〈U〉〈C〉《米》その根の部分《英》beetroot) / 〈C〉砂糖大根
5. 〈C〉回転おもちゃ(こま・風車など) / 〈C〉回転木馬 / 〈U〉〈C〉回転運動;変転
6. =beetle {形}

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/08/03 12:34:51」(JST)

wiki en

[Wiki en表示]

Whirligig beetle
Gyrinus natator, 1909 illustration
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Coleoptera
Suborder:	Adephaga
Family:	Gyrinidae Latreille, 1802
Genera
Anagyrinus (fossil) Andogyrus Angarogyrus (fossil) Aulonogyrus Avitortor (fossil) Baissogyrus (fossil) Cretotortor (fossil) Dineutus Enhydrus Gyretes Gyrinoides Gyrinopsis (fossil) Gyrinulopsis (fossil) Gyrinus Heterogyrus Macrogyrus Mesodineutes (fossil) Mesogyrus (fossil) Metagyrinus Miodineutes (fossil) Orectochilus Orectogyrus Porrorhynchus Protogyrinus Spanglerogyrus

The whirligig beetles are a family (Gyrinidae) of water beetles that usually swim on the surface of the water if undisturbed, though they swim actively underwater when threatened. They get their common name from their habit of swimming rapidly in circles when alarmed, and are also notable for their divided eyes which are believed to enable them to see both above and below water. The family includes some 700 extant species worldwide, in 15 genera, plus a few fossil species. Most species are very similar in general appearance, though they vary in size from perhaps 3 mm to 18 mm in length. They tend to be flattened and rounded in cross section, in plan view as seen from above, and in longitudinal section. In fact their shape is a good first approximation to an ellipsoid, with legs and other appendages fitting closely into a streamlined surface.

Taxonomy

The Gyrinidae generally have been regarded as a family in the Adephaga, but there is a great deal of work underway to clarify the relationships both within the Adephaga and within the Coleoptera in general. Within the Adephaga there is confusion as well, with various rival proposals in contention; for example some workers regard the Gyrinidae as being closely related to such families as the Dytiscidae and various other predacious water beetle families, whereas other analyses suggest rather that the Gyrinidae are a sister group to the rest of the Adephaga. Some of the Adephagan families seem to be polyphyletic themselves, so a definitive cladistic structure will have to await more advanced nucleic acid analyses.

Description

Whirligig beetles are most conspicuous by reason of their bewildering swimming, but their coloration is not showy and commonly they can be quite hard to see if they are not moving or are under water. However, seen to best effect most species are handsomely coloured with a sombre lustre of steely grey or bronze. Their integument is finely sculpted with little pits; it is hard and elastic and produces a water repellent waxy outer layer, constantly supplemented. Among other functions, the lubricant layer and smooth outline make the beetles remarkably difficult to hold on to if caught; they slip from between one's fingers like a fresh orange pip.

The antennae are unusual among beetles, being short and plump, and placed about at water level. The compound eyes are remarkable for each being divided into a higher part that is above water level when a beetle is floating passively, and a lower part that is below water level. In this respect they recall the Four-eyed fish. The middle, and more especially the hind, legs are natatory, meaning adapted for swimming; they are greatly flattened and fringed with bristles that fold to aid swimming action. In contrast the front legs are long and adapted for grasping food or prey. In males the front tarsi have suckers, which they need for holding onto slippery females during mating.

Behavior and morphological adaptations

The Gyrinidae are surface swimmers for preference. They are known for the bewildering and rapid gyrations in which they swim, and for their gregarious behavior. Most species also can fly well, even taking off from water if need be. The combination constitutes a survival strategy that helps them to avoid predation and take advantage of mating opportunities. In general the adults occupy areas where water flows steadily and not too fast, such as minor rapids and narrows in leisurely streams. Such places supply a good turnover of floating detritus or struggling insects or other small animals that have fallen in and float with the current.

The positions that individuals occupy within a group are determined by a number of factors, thought to include hunger, sex, species, water temperature, age, parasite level and stress level. Research underway on their behavior is directed at investigating the significance of chemical defense in relation to their position in the group. Such studies are of interest in research into aspects of nanotechnology because the beetles' motion may be expected to provide insights into how groups of robots might coordinate movements.

In particular the beetles make behavioral trade-offs that affect their choices of positions within a group. For example, relatively hungry beetles go to the outside of a group, where there is less competition for finding food, but higher risk of encountering predators. Males are also more likely to be found on the outside of groups (although grouping is not known to be relevant to mating behavior in this family). The economies that the beetles can gain by suitably adjusting their positions within the group, are important when individuals swim against the flow of a stream. By swimming behind other beetles they can take advantage of forward-moving drafts. Such action is called drafting. The determination of forward/backward positioning within a group has been found to be affected in a complex manner by a combination of water speed, sex of the beetle, and the type of predator (bird or fish) that a beetle has most recently observed.

The adult beetles carry a bubble of air trapped beneath their elytra. This allows them to dive and swim under well-oxygenated water for indefinite periods if necessary. The mechanism is sophisticated and amounts to a physical gill. In practice though, their ecological adaptation is for the adults to scavenge and hunt on the water surface, so they seldom stay down for long. The larvae have paired plumose tracheal gills on each of the first eight abdominal segments.

Generally Gyrinids lay their eggs under water, attached to water plants, typically in rows. Like the adults, the larvae are active predators, largely benthic inhabitants of the stream bed and aquatic plants. They have long thoracic legs with paired claws. Their mandibles are curved, pointed, and pierced with a sucking canal. In this they resemble the larvae of many other predatory water beetles, such as the Dytiscidae. Mature larvae pupate in a cocoon that also is attached to water plants.

Larva and Adult

Gyrinus Head, lateral aspect showing placement of antenna and divided compound eye

Hind leg of Gyrinus

Antenna of Gyrinus

References

• Ross H. Arnett, Jr. & Michael C. Thomas (2001). American Beetles. CRC Press. 
• William L. Romey; Rossman, David S (1995). "Temperature and hunger alter grouping trade-offs in whirligig beetles". The American Midland Naturalist 134 (1): 51–62. doi:10.2307/2426482. JSTOR 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 (3): 195–200. doi:10.1007/BF00176717. 
• William L. Romey & Abigail C. Wallace (2007). "Sex and the selfish herd: sexual segregation within nonmating whirligig groups". Behavioral Ecology 18 (5): 910–915. doi:10.1093/beheco/arm057. 
• 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 (2): 338–343. doi:10.1093/beheco/arm138. 

External links

• Gyrinidae Tree of Life
• Data related to Gyrinidae at Wikispecies

UpToDate Contents

全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.

• 1. 成人における吸入剤の到達 delivery of inhaled medication in adults

English Journal

• Tip-dated phylogeny of whirligig beetles reveals ancient lineage surviving on Madagascar.

• Gustafson GT1, Prokin AA2, Bukontaite R3, Bergsten J3, Miller KB4.
• Scientific reports.Sci Rep.2017 Aug 22;7(1):8619. doi: 10.1038/s41598-017-08403-1.
• PMID 28831048

• Flash Expansion Threshold in Whirligig Swarms.

• Romey WL1, Lamb AR1.
• PloS one.PLoS One.2015 Aug 24;10(8):e0136467. doi: 10.1371/journal.pone.0136467. eCollection 2015.
• PMID 26301958

• The New World whirligig beetles of the genus Dineutus Macleay, 1825 (Coleoptera, Gyrinidae, Gyrininae, Dineutini).

• Gustafson GT1, Miller KB1.
• ZooKeys.Zookeys.2015 Jan 23;(476):1-135. doi: 10.3897/zookeys.476.8630. eCollection 2015.
• PMID 25685002

Japanese Journal

• コオナガミズスマシ(甲虫目, ミズスマシ科)の京都における再発見と形態

• 吉安 裕,広岡 佑太,中尾 史郎
• 京都府立大学学術報告. 生命環境学 64, 9-13, 2012-12-25
• … An endangered water beetle, Orectochilus punctipennis, was newly discovered in Kamogawa River, Kyoto City, and this is the second collecting record since 1884 in Kyoto Prefecture. …
• NAID 110009555824

• オオミズスマシの飼育下繁殖について

• 竹田 正義
• ホシザキグリーン財団研究報告 (15), 275-285, 2012-03
• NAID 40019299228

• PIVを用いたミズスマシ遊泳時の可視化(バイオ・マイクロ・スポーツの流れ 生物の流れ,一般講演)

• 高木 直樹,深瀬 雅央,北川 一敬,田中 康恵,早坂 航平
• 日本流体力学会年会講演論文集 2009, 360, 2009-09-02
• … The aim of the present work is to investigate the flow behavior of swimming whirligig beetle. … The swimming behavior of whirligig beetle was visualized by a high speed camera recording and PIV. … The aquatic insect was Gyrinidae species whirligig beetle (Gyrinus japonicus). …
• NAID 110008459990

Related Links

• Whirligig beetle - Wikipedia, the free encyclopedia

The whirligig beetles are a family (Gyrinidae) of water beetles that usually swim on the surface of the water if undisturbed, though they swim actively underwater when threatened. They get their common name from their habit of swimming ...

---

★リンクテーブル★

関連記事	「beet」「beetle」

「beet」

　　[★]

テンサイ、フダンソウ

関

Beta vulgaris、chard

　 　 　

「beetle」

　　[★]

カブトムシ

関

Coleoptera