| Gerridae | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
 Adult Water Strider Gerris remigis
|
||||||||||||||
| Scientific classification | ||||||||||||||
|
||||||||||||||
| Genera | ||||||||||||||
|
Aquarius |
The family Gerridae contains insects commonly known as water striders, water bugs, magic bugs, pond skaters, skaters, skimmers, water scooters, water skaters, water skeeters, water skimmers or water skippers. Arthropods are Animals belonging to the Phylum Arthropoda (from Greek ἄρθρον arthron, " Joint " Insects ( Class Insecta) are a major group of Arthropods and the most diverse group of Animals on the Earth with over a million described Hemiptera is an order of Insects comprising around 80000 Species of Cicadas Aphids Planthoppers Leafhoppers Heteroptera is a group of about 40000 species of insects in the Hemiptera. Hemiptera is an order of Insects comprising around 80000 Species of Cicadas Aphids Planthoppers Leafhoppers William Elford Leach FRS ( 2 February 1790 – 26 August 1836) was an English Zoologist and Marine biologist These are predatory insects which rely on surface tension to walk on top of water. Insects ( Class Insecta) are a major group of Arthropods and the most diverse group of Animals on the Earth with over a million described For the work of fiction see Surface Tension (short story. Surface tension is a property of the surface of a Liquid that causes it to Water is a common Chemical substance that is essential for the survival of all known forms of Life. They live on the surface of ponds, slow streams, marshes, and other quiet waters. They can move very quickly, up to 1. 5 m/s.
"Five species of Halobates sea skaters are the only insects that have successfully colonized open ocean habitats. [. . . ] H. micans populations from the Pacific, Atlantic and Indian Oceans have been isolated for 1 to 3 million years". [1]
Contents |
Propulsion method
Animals such as water striders that live on the surface of water need to push something backwards to generate a reaction force (that is, Newton's third law of motion). Newton's laws of motion are three Physical laws which provide relationships between the Forces acting on a body and the motion of the
It was originally thought that water striders transferred momentum to the water by the creation of capillary waves on the surface. In Classical mechanics, momentum ( pl momenta SI unit kg · m/s, or equivalently N · s) is the product A capillary wave is a Wave travelling along the interface between two fluids whose dynamics are dominated by the effects of Surface tension. However, biophysicist Mark Denny showed that to do this, some object must move faster than about 0. Mark W Denny (born 1951 is a professor of biology at Stanford University. 25 m/s—far faster than a water strider can move its legs. This apparent contradiction is known as Denny's paradox. In the study of Animal locomotion, Denny's paradox refers to the apparent impossibility of surface-dwelling animals such as the Water strider generating enough propulsive
Water striders beat Denny's paradox by generating not capillary waves but hemispherical vortices in the water. V erification of the O rigins of R otation in T ornadoes Ex periment or VORTEX, is a field project that seeks to understand how a These vortices carry sufficient backwards momentum to propel the animal forwards.
In a series of experiments, mathematician John W. A mathematician is a person whose primary area of study and research is the field of Mathematics. M. Bush and several graduate students showed that during the rowing stroke, water striders drive their middle legs backwards without penetrating the surface, and can attain speeds of up to 1. 5 m/s.
Besides skating on the surface of water, most adult water striders can also use wings (e. g. to fly to another body of water). In many species the presence or absence of wings in the adults is a polymorphism; that is, only at certain times of year, or under certain conditions, do adults develop wings in order to disperse, while at other times, they conserve their developmental resources and develop as wingless adults. [1]
Nature of the hydrophobic legs
Water striders can stand effortlessly on water due to their non-wetting legs. The arthropod leg is a form of jointed Appendage of Arthropods usually used for Walking. Writing in Nature, biophysicists Xuefeng Gao and Lei Jiang show that the water resistance of the legs is due to the "special hierarchical structure of the legs, which are covered by large numbers of oriented tiny hairs (microsetae) with fine nanogrooves". Nature is a prominent Scientific journal, first published on 4 November 1869 Biophysics (also biological physics) is an Interdisciplinary Science that employs and develops theories and methods of the Physical sciences for Xuefeng Gao (born March 22, 1980) is a Chinese speed skater who competed in the 2006 Winter Olympics in Turin. Hair is a keratinised protein filament that grows through the epidermis from follicles deep within the Dermis. They go on to demonstrate that the water resistance is due more to this physical structure than the chemical properties of the wax coating of the legs. Wax has traditionally referred to a substance that is secreted by Bees ( Beeswax) and used by them in constructing their
Gao and Jiang calculate the maximal supporting force of a single leg to be is 1. 52 millinewtons (152 dynes or 0. The newton (symbol N) is the SI derived unit of Force, named after Isaac Newton in recognition of his work on Classical 011 poundal), which is about 15 times the total body weight of the insect. The poundal is a non- SI unit of Force. It is a part of the Foot-pound-second system of units a coherent subsystem of English units introduced This shows that the surface of the leg is strikingly water repellent.
For comparison, Gao and Jiang made a hydrophobic 'leg' from a smooth quartz fibre that was similar in shape and size to a strider's leg. In Chemistry, hydrophobicity (from the combining form of water in Attic Greek hydro- and for fear phobos) refers to the physical property of Quartz (from German) is the most abundant Mineral in the Earth 's Continental crust (although Feldspar is more common in Fiber or fibre is a class of Materials that are continuous filaments or are in discrete elongated pieces similar to lengths of thread. Its surface was coated with a thin layer of heptadecafluorodecyltrimethoxysilane (FAS-17), whose contact angle with water is 109°. The contact angle is the Angle at which a Liquid / Vapor interface meets the solid surface Water is a common Chemical substance that is essential for the survival of all known forms of Life. However, this artificial leg supported a force of only 0. 19 mN (19 dyn or 0. 0014 pdl): this would be just about enough to support the strider at rest, but not to enable it to dart around rapidly on the surface.
Gao and Jiang went on to calculate that the contact angle with water on a real strider's leg would be greater than 150° (and described this using the neologism 'superhydrophobic') and, using a sessile water-drop showed that the contact angle of the insect's legs with water was 167. A neologism (from Greek neo = "new" + logos = "word" is a word that although devised relatively recently in a specific time period has been In Chemistry, hydrophobicity (from the combining form of water in Attic Greek hydro- and for fear phobos) refers to the physical property of 6° ± 4. 4°.
They went on to infer that the observed superhydrophobicity was due to microstructures on the legs and, using a scanning electron microscope, showed that the legs were covered in many needle shaped setae, with diameters ranging from 3 micrometres down to a few hundred nanometres. The scanning electron microscope ( SEM) is a type of Electron microscope that images the sample surface by scanning it with a high-energy beam of Electrons Seta (plural setae) is a biological term derived from the Latin word for " Bristle " A micrometre ( American spelling: micrometer; symbol µm) is one millionth of a Metre, or equivalently one thousandth of a Millimetre A nanometre ( American spelling: nanometer, symbol nm) ( Greek: νάνος nanos dwarf; μετρώ metrό count) is a Most of the setae were about 50 micrometres long and were at an angle of about 20° from the surface of leg. Each microseta also had nanoscale grooves, contributing to the hierarchical structure of the leg.
Gao and Jiang used Cassie's law to show that air is trapped in spaces in the microsetae and nanogrooves, forming a cushion at the leg–water interface. Cassie's law describes the effective Contact angle θ c for a liquid on a composite surface. Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five This cushion prevents the legs from being wetted.
See also
- Veliidae (Smaller water strider)
- Animal locomotion on the surface layer of water
Sources and notes
- Gao X, Jiang L (2004). Veliidae is a family of predatory Insects in the suborder Heteroptera. Animal locomotion on the surface layer is the study of Animal locomotion in the case of small Animals that live on the surface layer of Water, relying on "Biophysics: water-repellent legs of water striders". Nature 432 (7013): 36. Nature is a prominent Scientific journal, first published on 4 November 1869 PMID 15525973.
Further reading
Dapyx Software network: MP3 Explorer | Ebook Manager | Zenithic