Whirligig beetle

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Whirligig beetle
Temporal range: Early Jurassic–Present
Gyrinus substriatus Stephens, 1828 (3968701087) (2).jpg
Gyrinus substriatus
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Coleoptera
Suborder: Adephaga
Family: Gyrinidae
Latreille, 1802
Subfamilies

The whirligig beetles are water beetles, comprising the family Gyrinidae that usually swim on the surface of the water if undisturbed, though they swim 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. [1] 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. [2] They tend to be flattened and rounded in cross section, in plain 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. Whirligig beetles belong to the beetle suborder Adephaga, which also includes ground beetles and diving beetles.

Contents

Description

Illustration of Gyrinus convexiusculus, with arrows pointing to the two pairs of eyes COLE Gyrinidae Gyrinius convexiusculus.png
Illustration of Gyrinus convexiusculus, with arrows pointing to the two pairs of eyes

Whirligig beetles are most conspicuous for their bewildering swimming. They can be difficult to see if they are not moving or are under water. Most species are coloured 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, which is constantly supplemented. Among other functions, the lubricant layer and smooth outline make the beetles difficult to hold on to if caught. [3]

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. [1] In this respect they recall the horizontally divided eyes of the four-eyed fishes (Anableps), which also live at the surface of the water. The middle, and more especially the hind legs are adapted for swimming (natatory): 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 are used to hold onto the slippery female during mating. [1]

Behavior and morphological adaptations

Video of swarming whirligig beetles

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.[ citation needed ]

Whirligig Beetle 01.jpg

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.[ citation needed ]

The beetles could use the waves generated by their moving as a sort of radar to detect the position of object on the water surface around them. This technique could be used to detect prey or to avoid colliding each other. [4]

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 Whirligigbeetle.PNG
Larva and Adult
Gyrinus Head, lateral aspect showing placement of antenna and divided compound eye Gyrinus Head1.jpg
Gyrinus Head, lateral aspect showing placement of antenna and divided compound eye
Hind leg of Gyrinus GyrinusLeg.jpg
Hind leg of Gyrinus
Antenna of Gyrinus GyrinusAntennae.jpg
Antenna of Gyrinus

Taxonomy

Whirligig beetles were previously grouped with other aquatic members of the Adephaga such as Dytiscidae, as members of the group "Hydradephaga". However based on molecular evidence they are currently thought to be the earliest diverging lineage of the Adephaga, and to have evolved their aquatic ecology independently from other adephagans. Cladogram after Vasilikopoulos et al. 2021 [5]

Adephaga

Gyrinidae

Geadephaga

Trachypachidae

Cicindelidae

Carabidae

Haliplidae

Dytiscoidea

Noteridae

Hygrobiidae

Aspidytidae

Amphizoidae

Dytiscidae

Internal taxonomy

Taxonomy after [6] [7] [8] [9]

Related Research Articles

<span class="mw-page-title-main">Cupedidae</span> Family of beetles

The Cupedidae are a small family of beetles, notable for the square pattern of "windows" on their elytra, which give the family their common name of reticulated beetles.

<span class="mw-page-title-main">Adephaga</span> Suborder of beetles

The Adephaga are a suborder of beetles, and with more than 40,000 recorded species in 10 families, the second-largest of the four beetle suborders. Members of this suborder are collectively known as adephagans. The largest family is Carabidae which comprises most of the suborder with over 40,000 species. Adephaga also includes a variety of aquatic beetles, such as predaceous diving beetles and whirligig beetles.

<span class="mw-page-title-main">Trachypachidae</span> Family of beetles

The Trachypachidae are a family of beetles that generally resemble small ground beetles, but that are distinguished by the large coxae of their rearmost legs. There are only six known extant species in the family, with four species of Trachypachus found in northern Eurasia and northern North America, and two species of Systolosoma in Chile and Argentina. They were much more diverse in the past, with dozens of described species from the Mesozoic.

<span class="mw-page-title-main">Dytiscidae</span> Family of beetles

The Dytiscidae – based on the Greek dytikos (δυτικός), "able to dive" – are the predaceous diving beetles, a family of water beetles. They occur in virtually any freshwater habitat around the world, but a few species live among leaf litter. The adults of most are between 1 and 2.5 cm (0.4–1.0 in) long, though much variation is seen between species. The European Dytiscus latissimus and Brazilian Megadytes ducalis are the largest, reaching up to 4.5 cm (1.8 in) and 4.75 cm (1.9 in) respectively. In contrast, the smallest is likely the Australian Limbodessus atypicali of subterranean waters, which only is about 0.9 mm (0.035 in) long. Most are dark brown, blackish, or dark olive in color with golden highlights in some subfamilies. The larvae are commonly known as water tigers due to their voracious appetite. They have short, but sharp mandibles and immediately upon biting, they deliver digestive enzymes into prey to suck their liquefied remains. The family includes more than 4,000 described species in numerous genera.

<span class="mw-page-title-main">Hydraenidae</span> Family of beetles

Hydraenidae is a family of very small aquatic beetles, sometimes called "Minute moss beetles", with a worldwide distribution. They are around 0.8 to 3.3 mm in length. The adults store air on the underside of the body as well as beneath the elytra which allows them to crawl underwater, often on the underside of the water surface tension, though they cannot swim. Some species have gills that effectively allow them to stay underwater indefinitely. Larvae vary from being fully terrestrial, to being aquatic at least in their earliest instars. The diet of hydraenid larvae and adults is thought to consist of algae, spores and other plant matter. At least some hydraenid adults use stridulation to communicate. There are around 1,300 species in 42 genera.

<span class="mw-page-title-main">Ommatidae</span> Family of beetles

The Ommatidae are a family of beetles in the suborder Archostemata. The Ommatidae are considered the extant beetle family that has most ancestral characteristics. There are only seven extant species, confined to Australia and South America. However, the geographical distribution was much wider during the Mesozoic spanning across Eurasia and Australia, suggesting that they were widespread on Pangea. So far, over 26 extinct genera containing over 170 species of these beetles have been described. Three extant genera have been assigned to this family: Omma,Tetraphalerus and Beutelius. The family is considered to be a subfamily of Cupedidae by some authors, but have been found to be more closely related to Micromalthidae in molecular phylogenies. A close relationship with Micromalthidae is supported by several morphological characters, including those of the mandibles and male genitalia. Due to their rarity, their ecology is obscure, it is likely that their larvae feed on deadwood.

<i>Andogyrus</i> Subgenus of beetles

Andogyrus is a subgenus of Macrogyrus, a genus of beetles in the family Gyrinidae. It was formerly considered a distinct genus, until a phylogenetic study in 2017 downgraded it in rank to a subgenus. It contains the following species:

Enhydrus is a genus of beetles in the family Gyrinidae, containing the following species:

Macrogyrus is a genus of beetles in the family Gyrinidae, containing the following species:

<i>Omma</i> Genus of beetles

Omma is a genus of beetles in the family Ommatidae. Omma is an example of a living fossil. The oldest species known, O. liassicum, lived during the final stage of the Triassic (Rhaetian), over 200 million years ago, though the placement of this species in Omma has been questioned. Numerous other fossil species are known from the Jurassic and Cretaceous of Europe and Asia. The only living species is Omma stanleyi, which is endemic to Australia. Three other extant species endemic to Australia that were formerly part of this genus were moved to the separate genus Beutelius in 2020.Omma stanleyi is strongly associated with wood, being found under Eucalyptus bark and exhibiting thanatosis when disturbed. Its larval stage and many other life details are unknown due to its rarity. Males are typically 14–20 mm in length, while females are 14.4-27.5 mm. Omma stanleyi occurs throughout eastern Australia from Victoria to Central Queensland.

<span class="mw-page-title-main">Gyrininae</span> Subfamily of beetles

Gyrininae is a subfamily of ground and water beetles in the family Gyrinidae. There are at least 740 described extant species in Gyrininae.

<i>Dineutus hornii</i> Species of beetle

Dineutus hornii is a species of whirligig beetle in the family Gyrinidae. It is found in North America.

<i>Dineutus carolinus</i> Species of beetle

Dineutus carolinus is a species of whirligig beetle in the family Gyrinidae. It is found in the Caribbean Sea, Central America, and North America.

<i>Dineutus ciliatus</i> Species of beetle

Dineutus ciliatus is a species of whirligig beetle in the family Gyrinidae. It is found in North America.

<i>Dineutus assimilis</i> Species of beetle

Dineutus assimilis is a species of whirligig beetle in the family Gyrinidae. It is found in North America.

<i>Dineutus sublineatus</i> Species of beetle

Dineutus sublineatus is a species of whirligig beetle in the family Gyrinidae. It is found in Central America and the Southwestern United States.

<i>Dineutus nigrior</i> Species of beetle

Dineutus nigrior is a species of whirligig beetle in the family Gyrinidae. It is found in North America.

<i>Dineutus discolor</i> Species of beetle

Dineutus discolor, the large whirligig beetle, is a species of whirligig beetle in the family Gyrinidae. It is found in Central America and North America.

Chimerogyrus gigagalea is a fossil species of beetle in the family Gyrinidae, the only known species in the genus Chimerogyrus. It is known from a larval form found in Cenomanian aged Burmese amber of Myanmar. it was found to be a member of Gyrininae, sister to Dineutini + Orectochilini.

References

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  8. Gustafson, G.T.; Prokin, A.A.; Bukontaite, R.; Bergsten, J.; Miller, K.B. (2017). "Tip-dated phylogeny of whirligig beetles reveals ancient lineage surviving on Madagascar". Scientific Reports . 7 (1): 8619. doi: 10.1038/s41598-017-08403-1 . PMC   5567340 . PMID   28831048.
  9. Gustafson, G.T.; Miller, K.B. (2017). "Systematics and evolution of the whirligig beetle tribe Dineutini (Coleoptera: Gyrinidae: Gyrininae)". Zoological Journal of the Linnean Society . 181 (1): 118–150. doi: 10.1093/zoolinnean/zlw014 .
  10. Zulong Liang; Zhihao Qi; Jiahui Chen; Fenglong Jia (2020). "Cretodineutus rotundus gen. et sp. nov., the oldest adult whirligig beetle from the Upper Cretaceous of Myanmar (Coleoptera, Gyrinidae, Gyrininae)". Cretaceous Research. 106: Article 104251. doi:10.1016/j.cretres.2019.104251. S2CID   204257893.
  11. 1 2 Gustafson, Grey T.; Michat, Mariano C.; Balke, Michael (2020). "Burmese amber reveals a new stem lineage of whirligig beetle (Coleoptera: Gyrinidae) based on the larval stage". Zoological Journal of the Linnean Society. 189 (4): 1232–1248. doi:10.1093/zoolinnean/zlz161. PMC   7398075 . PMID   32780030.