Notonecta glauca

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Notonecta glauca
Notonecta glauca1.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hemiptera
Suborder: Heteroptera
Family: Notonectidae
Genus: Notonecta
Species:
N. glauca
Binomial name
Notonecta glauca

Notonecta glauca (common backswimmer) is a species of aquatic insect, and a type of backswimmer. This species is found in large parts of Europe, North Africa, and east through Asia to Siberia and China. [1] In much of its range it is the most common backswimmer species. [2] It is also the most widespread and abundant of the four British backswimmers. [3] Notonecta glauca are Hemiptera (true bug) predators, [2] that are approximately 13–16 mm in length. [4] Females have a larger body size compared to males. [2] These water insects swim and rest on their back (hence their common name "backswimmer" or "water boatman") and are found under the water surface. [5] Notonecta glauca supports itself under the water surface by using their front legs and mid legs and the back end of its abdomen and rest them on the water surface; [6] They are able to stay under the water surface by water tension, also known as the air-water interface (surface tension). [7] They use the hind legs as oars; these legs are fringed with hair and, when at rest, are extended laterally like a pair of sculls in a boat. [8] Notonecta glauca will either wait for its prey to pass by or will swim and actively hunt its prey. When the weather is warm, usually in the late summer and autumn, they will fly between ponds. [9] [10] Notonecta glauca reproduce in the spring. [2]

Contents

Eye

Compound eye Eyes of the beholder.jpg
Compound eye

There has been a great deal of research on the eye of N. glauca. These insects use their eyes for both day and night vision, which is used for prey capture and flight when searching for new habitats. [5] Notonecta glauca, like other insects, have a compound eye. Specifically, their eye is an acone-type with corneal structure, which helps them create a sharp image when both in the water and in the air. [11] [12] [13] The acone is the site of the pupil. Immonen et al. (2014), found that backswimmers are able to see in both day and night light conditions because of:

They also found that the green-sensitive peripheral photoreceptors function in a similar way as nocturnal Phasmatodea (or stick insects). To protect their eye from direct sunlight during the day, the pigment cell's diaphragm are condensed, and during the night they open fully to allow as much light in as possible. [5] Notonecta glauca have two photoreceptor subsystems:

  1. Large and most sensitive peripheral photoreceptors
  2. Smaller peripheral and central photoreceptors

The first subsystem is sensitive to green light, one of the colours in the visible spectrum. This sensitivity helps the backswimmer see in dimmer light or at night. The second subsystem allows the backswimmer to see in bright light and when in flight. [5] Notonecta glauca pupil (acone) take a different amount of time to adjust to light. It takes the N. glauca approximately 40 minutes for the pupil to adjust to daylight and approximately 50 minutes to adjust to the light at night. [14]

Air retention

Notonecta glauca Notonecta glauca01.jpg
Notonecta glauca

Although N. glauca live in the water, they breathe atmosphere air and do not have gills. When these insects are diving or resting under the water surface, they create a film of air that surrounds their body. [15] This air film is also known as a superhydrophobic coating or surface, and it prevents the insect from becoming wet. [4] It also reduces the drag (physics) that is created when diving. [16] [17] To be able to create this air film around it, N. glauca is covered in hairy structures, except on its head and legs. [15] There are two types of hairs and air retention is maximized by having both types: setae and microtrichia. [15] The most important part in creating an air film is the density of the hairs. [4] Notonecta glauca has dense microtrichia and their air film can last up to 120 days. [4] The air film cannot last forever because as an insect respires (breathes), the oxygen partial pressure will decrease and nitrogen partial pressure will increase, causing the air bubble to decrease in size. [4]

Model organism

Notonecta glauca is used as a model organism for friction reduction and air retention. [15] Possible applications for this include reduction of drag in ships.

Wave discrimination

Notonecta glauca can discriminate between prey and non-prey, like other backswimmers, by surface waves. [18] Lang (1979), completed an experiment that showed that waves that were created by other backswimmers swimming, emerging, turning and paddling were of a lower frequency (below 40 Hz) compared to waves created by their prey items, who had a frequency between 70–140 Hz. Larval backswimmers were found to create different waves that differed from adult backswimmers, but their frequency were similar to that of adult swimming produced waves (up to 70 Hz).

Foraging behaviour

Asellus aquaticus Asellus aquaticus.jpg
Asellus aquaticus

Water depth can affect how N. glauca pick which prey they eat. Males and females both spend a lot of time on the surface of the water where they encounter mosquito ( Culex ) larvae. They feed on this prey because there is a decrease in travel cost (having to dive for them) and Culex gives a higher energy rate. [19]

Adult Culex mosquito Culex mosquito (4620846673).jpg
Adult Culex mosquito

Mature females, however, will also dive to the bottom of the pond to feed on isopods ( Asellus ), but only in shallow waters. [19] Reaching Asellus requires a higher travel cost of energy. This behaviour is not consistent with the optimal foraging theory. [19] It is possible, however, that because mature females are larger than males and immature females, they have a reduced buoyancy and therefore require less energy to capture Asellus. [20] Also, mature females have a larger abdominal size, which could support a larger air bubble and allow them to remain submerged for longer. [19] However, if the water depth increases, mature females will switch and spend more time at the surface and not feed on Asellus, as the deep water increases the amount of energy needed for diving and staying submerged. [19]

The oxygen concentration in the body of water can affect the choice of prey N. glauca pick, as Cockrell (1984) found that when oxygen was at a high dissolved level, N. glauca will spend more time submerged and attacking Asellus. [21]

Notonecta glauca feeding Notonecta.glauca.jpg
Notonecta glauca feeding

Related Research Articles

<span class="mw-page-title-main">Eye</span> Organ that detects light and converts it into electro-chemical impulses in neurons

Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and convert it into electro-chemical impulses in neurons (neurones). In higher organisms, the eye is a complex optical system which collects light from the surrounding environment, regulates its intensity through a diaphragm, focuses it through an adjustable assembly of lenses to form an image, converts this image into a set of electrical signals, and transmits these signals to the brain through complex neural pathways that connect the eye via the optic nerve to the visual cortex and other areas of the brain. Eyes with resolving power have come in ten fundamentally different forms, and 96% of animal species possess a complex optical system. Image-resolving eyes are present in molluscs, chordates and arthropods.

<span class="mw-page-title-main">Hemiptera</span> Order of insects often called true bugs

Hemiptera is an order of insects, commonly called true bugs, comprising over 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, assassin bugs, bed bugs, and shield bugs. They range in size from 1 mm (0.04 in) to around 15 cm (6 in), and share a common arrangement of piercing-sucking mouthparts. The name "true bugs" is often limited to the suborder Heteroptera.

<span class="mw-page-title-main">Lesser water boatman</span> Species of true bug

The lesser waterboatman or lesser water boatman is a water-dwelling insect of the order Hemiptera.

<span class="mw-page-title-main">Aquatic insect</span> Insect that lives in water

Aquatic insects or water insects live some portion of their life cycle in the water. They feed in the same ways as other insects. Some diving insects, such as predatory diving beetles, can hunt for food underwater where land-living insects cannot compete.

<span class="mw-page-title-main">Pentatomoidea</span> Superfamily of true bugs

The Pentatomoidea are a superfamily of insects in the Heteroptera suborder of the Hemiptera order. As Hemiptera, they share a common arrangement of sucking mouthparts. The roughly 7000 species under Pentatomoidea are divided into 21 families. Among these are the stink bugs and shield bugs, jewel bugs, giant shield bugs, and burrower bugs.

<span class="mw-page-title-main">Reduviidae</span> Family of insects

The Reduviidae is a large cosmopolitan family of the order Hemiptera. Among the Hemiptera and together with the Nabidae almost all species are terrestrial ambush predators; most other predatory Hemiptera are aquatic. The main examples of nonpredatory Reduviidae are some blood-sucking ectoparasites in the subfamily Triatominae. Though spectacular exceptions are known, most members of the family are fairly easily recognizable; they have a relatively narrow neck, sturdy build, and a formidable curved proboscis. Large specimens should be handled with caution, if at all, because they sometimes defend themselves with a very painful stab from the proboscis.

<span class="mw-page-title-main">Gerridae</span> Family of true bugs

The Gerridae are a family of insects in the order Hemiptera, commonly known as water striders, water skeeters, water scooters, water bugs, pond skaters, water skippers, water gliders, water skimmers or puddle flies. Consistent with the classification of the Gerridae as true bugs, gerrids have mouthparts evolved for piercing and sucking, and distinguish themselves by having the unusual ability to walk on water, making them pleuston (surface-living) animals. They are anatomically built to transfer their weight to be able to run on top of the water's surface. As a result, one could likely find water striders present in any pond, river, or lake. Over 1,700 species of gerrids have been described, 10% of them being marine.

<span class="mw-page-title-main">Corixidae</span> Family of true bugs

Corixidae is a family of aquatic insects in the order Hemiptera. They are found worldwide in virtually any freshwater habitat and a few species live in saline water. There are about 500 known species worldwide, in 55 genera, including the genus Sigara.

<span class="mw-page-title-main">Notonectidae</span> Family of true bugs

Notonectidae is a cosmopolitan family of aquatic insects in the order Hemiptera, commonly called backswimmers because they swim "upside down" (inverted). They are all predators and typically range from 0.5 to 1.5 cm (0.2–0.6 in) in length. They are similar in appearance to Corixidae, but can be separated by differences in their dorsal-ventral coloration, front legs, and predatory behavior. Their dorsum is convex, lightly colored without cross striations. Their front tarsi are not scoop-shaped and their hind legs are fringed for swimming. There are about 350 species in two subfamilies: Notonectinae with seven genera, and Anisopinae with four genera. Members in the former subfamily are often larger than those in the latter.

<span class="mw-page-title-main">Belostomatidae</span> Family of true bugs

Belostomatidae is a family of freshwater hemipteran insects known as giant water bugs or colloquially as toe-biters, Indian toe-biters, electric-light bugs, alligator ticks, or alligator fleas. They are the largest insects in the order Hemiptera. There are about 170 species found in freshwater habitats worldwide, with more than 110 in the Neotropics, more than 20 in Africa, almost as many in the Nearctic, and far fewer elsewhere. These predators are typically encountered in freshwater ponds, marshes and slow-flowing streams. Most species are at least 2 cm (0.8 in) long, although smaller species, down to 0.9 cm (0.35 in), also exist. The largest are members of the genus Lethocerus, which can exceed 12 cm (4.5 in) and nearly reach the length of some of the largest beetles in the world. Giant water bugs are a popular food in parts of Asia.

<span class="mw-page-title-main">Ultrahydrophobicity</span> Material property of extreme resistance to wetting

In chemistry and materials science, ultrahydrophobic surfaces are highly hydrophobic, i.e., extremely difficult to wet. The contact angles of a water droplet on an ultrahydrophobic material exceed 150°. This is also referred to as the lotus effect, after the superhydrophobic leaves of the lotus plant. A droplet striking these kinds of surfaces can fully rebound like an elastic ball. Interactions of bouncing drops can be further reduced using special superhydrophobic surfaces that promote symmetry breaking, pancake bouncing or waterbowl bouncing.

<span class="mw-page-title-main">Nepomorpha</span> Infraorder of true bugs

Nepomorpha is an infraorder of insects in the "true bug" order (Hemiptera). They belong to the "typical" bugs of the suborder Heteroptera. Due to their aquatic habits, these animals are known as true water bugs. They occur all over the world outside the polar regions, with about 2,000 species altogether. The Nepomorpha can be distinguished from related Heteroptera by their missing or vestigial ocelli. Also, as referred to by the obsolete name Cryptocerata, their antennae are reduced, with weak muscles, and usually carried tucked against the head.

<i>Lethocerus</i> Genus of true bugs

Lethocerus is a genus of the hemipteran family Belostomatidae, known colloquially as giant water bugs, toe biters and electric light bugs, distributed in tropical, subtropical and temperate areas of the world. The greatest diversity of species occurs in the Americas, with only a single species in Europe, two in Africa, two in Australia and three in Asia. It includes the largest true bugs with species capable of reaching a length of over 12 centimetres (4.7 in). The South American L. grandis and L. maximus are the only species to commonly exceed 9 cm (3.5 in), with more typical lengths for the remaining species being between 4.5 and 9 cm. Lethocerus sp. are distinguished from other genera in the Lethocerinae by two symmetrical furrows in the inner pad of setae on the fore femur, the external borders of parasternites II and III narrowed and nearly straight, and with the setae of the tarsomeres following the line of the tibial setae.

<i>Thermonectus marmoratus</i> Species of beetle

Thermonectus marmoratus is a relatively colorful North American species of diving beetle known by the common names sunburst diving beetle and yellow-spotted diving beetle. The behavior of this diving beetle has been compared to a scuba diver, since it carries with it a bubble of air as it dives down into the water. Its aquatic larval stage was the first ever recorded use of bifocals in the animal world. The beetle uses in its principal eyes two retinas and two distinct focal planes that are substantially separated, in the manner of bifocals to switch their vision from up-close to distance, for easy and efficient capture of their prey.

<i>Notonecta maculata</i> Species of true bug

Notonecta maculata is a backswimmer of the family Notonectidae, found in Europe, including the United Kingdom.

<i>Notonecta undulata</i> Species of true bug

Notonecta undulata, also known by the common name grousewinged backswimmer, are from the family Notonectidae and the insect suborder Heteroptera. They are a type of hemipteran or true bug. These aquatic insects typically spend their time at the water's surface, using their abdomen and legs to cling to the underside of the surface tension. The Grousewinged backswimmer can be found in both lotic and lentic environments; however, they typically prefer small ponds and lakes where the water is slow-moving with less current. They swim upside down looking for prey. Once they stop swimming they float back up to the surface. These insects can be distinguished from water boatman or Corixidae by their segmented beak and front legs. Water boatman have highly modified front legs whereas backswimmers do not. Backswimmers are distributed across a broad range throughout North America. However, the species Notonecta undulata has only been documented and studied in southern Manitoba, Saskatchewan, Alberta and the western United States. N. undulata differs from other backswimmers by their antennae and size. They are approximately 10–12 mm long, and their antennae are 4 segmented.

The Salvinia effect describes the permanent stabilization of an air layer upon a hierarchically structured surface submerged in water. Based on biological models, biomimetic Salvinia-surfaces are used as drag reducing coatings (up to 30% reduction were previously measured on the first prototypes. When applied to a ship hull, the coating would allow the boat to float on an air-layer; reducing energy consumption and emissions. Such surfaces require an extremely water repellent super-hydrophobic surface and an elastic hairy structure in the millimeter range to entrap air while submerged. The Salvinia effect was discovered by the biologist and botanist Wilhelm Barthlott and his colleagues and has been investigated on several plants and animals since 2002. Publications and patents were published between 2006 and 2016. The best biological models are the floating ferns with highly sophisticated hierarchically structured hairy surfaces, and the back swimmers with a complex double structure of hairs and microvilli. Three of the ten known Salvinia species show a paradoxical chemical heterogeneity: hydrophilic hair tips, in addition to the super-hydrophobic plant surface, further stabilizing the air layer.

<i>Musgraveia sulciventris</i> Species of true bug

Musgraveia sulciventris is a large stink bug found in Australia, sometimes known as the bronze orange bug. It is considered a pest, particularly to plants in the citrus group. Bronze orange bugs suck the sap from trees, which causes the flowers and fruit to fall.

Gerris buenoi is a species of water strider that belongs to the family Gerridae. It was first identified in 1911 and is native to continental USA and Canada. Individuals of this species are small in size and have modified appendages, allowing them to float and "skate" along the surface of the water. G. buenoi can be found near the shoreline of freshwater ponds and small lakes, where they hunt for terrestrial insects that have fallen into the water.

References

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