The Gerridae is an insect family in the Hemiptera order, commonly known as water striders , water insects , skater pond , < b> water skipper , or jesus bug . Consistent with Gerridae classification as an actual bug ( ie, suborder Heteroptera), gerials have mouths evolved to pierce and suck, and differentiate themselves by having unusual abilities to walk on water, making them pleuston (live surface) animals. They are anatomically built to transfer their weight to run on the surface of the water. As a result, one might be able to find water striders present in any pond, river, or lake. Scientists have identified more than 1,700 species of grinding, 10% of them are marine.
While 90% of Gerridae is a freshwater bug, the oceans of Halobates make families quite unusual among insects. The genus Halobates was first studied in depth between 1822 and 1883 when Buchanan-White collected several different species during the Challenger Expedition. Around this time, Eschscholtz discovered three Gerridae species, bringing attention to the species, although little of their biology is known. Since then, Gerridae continues to be studied for their ability to walk on water and unique social characteristics. Small gerrids are often confused with other semiaquatic bugs, Veliidae. The most consistent characteristic used to separate these two families is the difference between the internal genitalia. Since internal genitalia require special training and tools to identify, it is almost impossible to tell Gerridae members apart from Veliidae members by external visual cues. One must study their habitat and behavior to distinguish the two without seeing their specific anatomy.
Video Gerridae
Description
The Gerridae family is physically characterized by having hydrofuge hair, retractable prehistoric claws, and elongated legs and body.
Hydrofuge hairpiles are small hydrophobic microhairs. These are small hairs with more than a thousand microhairs per mm. The entire body is covered by these hairpiles, providing water strider resistance to splashes or water droplets. These hairs repel water, preventing droplets from burdening the body.
Size
They are generally small, long-legged insects and the body length of most species is between 2 and 12 mm (0.08-0.47 inches). Some of them are between 12 and 25 mm (0.47-0.98 inches). Among the broadest genera, the Northern Hemisphere is among the largest species, generally exceeding 12 mm (0.47 inches), at least among females, and the largest species averaging about 24 mm (0.94 inches). Women are usually on average larger than men of their own species, but seem to be reversed in the largest, relatively less known species of Gigantometra gigas from streams in northern Vietnam and adjacent southern China. It typically reaches a body length of about 36 mm (1.42 inches) in men without wings and 32 mm (1.26 inches) in winged women (winged men, however, only slightly larger on average than females). In this species every middle and rear leg can exceed 10 cm (4 inches).
Antennae
Air striders have two antennas with four segments on each. The antenna segment is numbered from the closest to the head to the furthest. The antenna has short, stiff hairs in segment III. The relative length of the antenna segment can help identify the unique species within the Gerridae family, but in general, segment I is longer and more contained than the remaining three. The four composite segments are usually no longer than the length of the water strider's head.
Thorax
Thorax water striders are generally long, narrow, and small in size. These generally range from 1.6 mm to 3.6 mm throughout the species, with some bodies more cylindrical or rounded than others. Pronotum, or outer layer of thorax, of a water strider may be shiny or dull depending on its species, and covered with microshair to help dissipate water. The water belly strider can have several segments and contain metasternum and omphalium.
Attachment
A pair of front, middle, and rear legs appeared. The shortest forelegs and has a preyed claw tailored to the prey puncture. Preapical claws are claws that are not on the toes, but half way, like mantides. The middle leg is longer than the first pair and shorter than the last pair and is adjusted for propulsion through water. The rear pair is the longest and is used to spread the weight in large surface areas, and direct the insects to the water surface. The forelegs are mounted directly at the back of the eye, while the center legs are mounted closer to the hind legs attached to the midthorax but extend past the terminal end of the body.
Wing
Some water striders have wings present on the dorsal side of their thorax, while other species of Gerridae are not - especially Halobates. Water striders experience long wing polymorphisms that have affected their flying ability and evolved phylogenetically in which populations either winged long, wing-dimorphic, or short-winged. Wing dimorphism consists of a summer gerrad population that develops different long wings of winter populations within the same species. Habitats with rougher water tend to hold the wing with shorter wings, while habitats with calm waters tend to have long winged motion. This is due to the potential for wing damage and the ability to spread.
Maps Gerridae
Wings polymorphism
Wings polymorphism is important for varieties and spread of Gerridae. The ability for a single parent to have a young with wings and the next does not allow the water striders to adapt to the changing environment. Long, medium, short, and nonexistent wings are all required depending on the environment and the season. The long wings allow to fly to the neighboring water bodies when one becomes too crowded, but they can get wet and weigh the strider's water down. Short wings allow for short trips, but limit how far outlets can spread. Non-existent wings prevent the tiles from being weighed, but prevent spread.
Wings polymorphism is common in Gerridae although most of the univoltine population is completely flavored (winged) or macropterous (with wings). The diverse population of tiles will be limited to stable aquatic habitats that have little change in the environment, while macropterous populations can inhabit more changes, changing water supplies. Stable water is usually a large lake and river, while unstable waters are generally small and seasonal. Gerim produces a winged form for the purpose of spreading and the individual macropter is retained because of their ability to survive under changing conditions. Wings are needed if the water body tends to dry because the gerrid must fly to a new water source. However, the wingless form is favored because competition for the development of ovaries and wings and reproductive success is a major goal because of the selfish gene theory. Drizzle rumbling is usually makropterous, or with wings, so they can fly back into their aquatic habitats after winter. An environmental switch mechanism controls the seasonal dimorphism observed in bivoltine species, or species that have two mains per year. This switch mechanism helps determine whether or not the mains with the wings will evolve. Temperature also plays an important role in the photoperiodic switch. Temperature signifies the seasons and thus when the wings are needed because they hibernate during the winter. Ultimately, this switching mechanism alters the genetic allele for wing characteristics, helping to maintain biological spread.
Nature of ability to walk on water
Water striders can walk on water because of a combination of several factors. Air striders use high tensile surface water and long and hydrophobic feet to help them stay on the water. Water molecules are polar and this causes them to attract each other.
Gerridae species use this surface tension to their advantage through their highly adaptable and heavily distributed legs. The strider's legs are long and slender, allowing the water strider's weight to be distributed over a large surface area. The legs are strong, but have the flexibility that allows the water strider to keep their weight evenly and flow with the movement of water. Hydrofuge hair coats the body surface of the water strider. There are several thousand hairs per square millimeter, providing a water strider with a hydrofuge body that prevents wetting from waves, rain, or sprays, which can hamper their ability to keep their entire body above the water surface if water is stuck and weigh on the body. This position keeps the majority of the body above the water surface called epipleustonic position, which is the hallmark of the water striders. If the body of the water strider inadvertently becomes submerged, for example by large waves, small hairs will trap the air. Small air bubbles throughout the body act as buoyancy to bring the water strider to the surface again, while also providing air bubbles to breathe from underwater.
The small feathers on the feet provide both a hydrophobic surface as well as a larger surface area to spread their weight over the water. The middle legs used to paddle have excellent peripheral hair developed on the tibia and tarsus to help improve movement through the ability to push. The back pair of the foot is used for steering. When the step of the paddle begins, the middle tank of the gerrid is rapidly pressed down and backwards to create a circular surface wave where the emblem can be used to push the thrust forward. The semicircle wave made is crucial for the ability of the water strider to move fast as it acts as a fighting force to push. As a result, water striders often move at speeds of 1 meter per second or faster.
Life cycle
Gerim generally lay eggs on submerged rocks or herbs using agar substances as glue. Gravid females carry between two and twenty eggs. Eggs are creamy white or clear, but become bright orange.
The movement passes through the egg stage, the five instar stages of the nymph forms, and then the adult stage. The duration of the water strider instar is highly correlated throughout the larval period. This means that individuals tend to develop at the same level through each instar stage. Each nymph stage lasts 7-10 days and water strider molts, shedding the old cuticle through a dorsal shaped Y-shaped to the head and chest. The nymphs are very similar to adults in behavior and diet, but are smaller (1 mm), more pale, and less differentiated in the tarsal and genital segments. It takes about 60 to 70 days for a water strider to reach adulthood, although this rate of development has been found to be highly correlated with the water temperature inside the egg.
Ecology
Habitat
Gerridae generally inhabits a calm water surface. The majority of water striders inhabit freshwater areas, with the exception of Asclepios , Halobates , Stenobates and several other sea water genera. Marine species are generally coastal, but some Halobates live offshore and are the only insects of this habitat. Gerridae prefers an abundant environment with insects or zooplankton and one that contains some stones or herbs for ovipocyte eggs. It has been studied by the prevalence of water striders in various environments, most water striders prefer waters about 25 degrees Celsius. Water temperatures lower than 22 degrees Celsius are not favorable. This may be due to the fact that the rate of development of young age depends on temperature [5]. The colder the water around it, the slower the younger developer develops. Gerridae's leading genera are present in Europe, former US, Canada, US, South Africa, South America, Australia, China, and Malaysia [5]. Nothing has been identified in the waters of New Zealand.
Diet
Gerris is an aquatic predator and feeds on invertebrates, especially spiders and insects, which fall to the surface of the water. Air striders are attracted to this food source by the ripples produced by struggling prey. The water strider uses its front legs as a sensor for vibrations generated by ripples in the water. The water strider pierces the body of a prey object with its trunk, injects a salivary enzyme that destroys the internal structure of its prey, and then sucks the resulting liquid. Gerris prefers life as a prey, even though they are indiscriminate feeders when it comes to terrestrial insect species. Halobates, which are found in the open ocean, feed on floating insects, zooplankton, and occasionally resort to their own nymph cannibalism. Cannibalism is common, but it helps control population size and limits conflicting areas. During non-married seasons when geraniums live in a cooperative group, and lower cannibalism levels, water striders will openly share a massive killing with others around them. Some of the cartridges are collectors, feeding from sediment or surface deposits.
Predator
The gerim, or water striders, are preyed mostly by birds and some fish. Petrel, terns, and some sea fish prey on Halobates. Fish do not seem to be the main predators of water striders, but will eat them in case of hunger. Scent gland secretion of the thorax is responsible for repelling the fish from eating them. Gerim is mostly hunted by birds of various species that depend on habitat. Some water striders are hunted by frogs, but they are not their main food source. Air striders are also sometimes hunted by each other. Strider water cannibalism mainly involves hunting nymphs for marriage and sometimes for food. To avoid predators, water striders will fly into neighboring pools or dive under water. This avoidance of predation helps the process of spreading and distributing species to a wider area. When species discover new land areas, they adapt to new environments. There are so many species of water strider as a result of this spread and adaptation over time.
Parasites
Some endoparasites have been found in the gerrid. Trypanosamatid flagellates, nematodes, and Hymenoptera parasites all act as endoparasites. The water mole larva acts as an ectoparasite of the water striders.
Dispersal
The sudden increase of salt concentration in gerrid water habitat can trigger the migration of water striders. The water strider will move to a lower salt concentration area, producing a mixture of genes in the brackish and freshwater bodies. Nutrition density also affects the spread of water striders. The higher density of the water striders in the nymph stage results in a higher percentage of brachypterous adults developing flight muscles. This flight muscle allows the water striders to fly to water bodies and adjacent pairs, resulting in the spread of genes. The spread and mixing of these genes can be beneficial because of the heterozygous advantages. Generally, water striders will try to dissolve in such a way as to decrease the gerer density in one area or water collection. Most do this by flight, but those without wings or wing muscles will depend on the flow of water bodies or floods. Eggs at Halobates are often placed in marine debris floating and thus spreading to the ocean by this drifting material.
Marital Behavior
Sex discrimination in Gerridae is determined by the frequency of ripple communication generated on the surface of the water. Men mainly produce these ripples in the water. There are three main frequencies found in the ripple communication: 25 Hz as a discharging signal, 10 Hz as a threat signal, and 3 Hz as a dating signal. The approaching bell will first pull out the signal to let the other water striders know that they are in their area. If another gerridge does not return a repel signal, then the bug knows that it is female and will switch to the dating signal. Receptive women will lower their stomach and allow men to ride and marry. A woman who refuses to accept will lift her stomach and issue a repel signal. Men who are allowed to marry are attached to the same female for the entire reproductive season. This is to ensure that the younger male females are peaked and thus ensure the spread of their genes. Females oviposit, or lay eggs, by soaking and attaching eggs to a stable surface such as plants or stones. Some species of water strider will lay eggs on the edge of the water if the body of water is quite calm. The number of eggs placed depends on the amount of food available to the mother during the reproductive season. The availability of food and dominance amongst other gerridges in the area plays an important role in the amount of food obtained and thus, produces fecundity. Water striders will reproduce year-round in the tropics where it remains warm, but only during warmer months in seasonal habitats. Gerrids living in wintery environments will withstand winter in the adult stage. This is because of the huge energy costs that must be spent to maintain their body temperature at a functional level. These water striders have been found in leaf litter or under stationary shelters such as wood and stone during the winter in seasonal areas. This reproductive diapause is the result of shortening the length of the day during the development of larvae and seasonal variation in lipid levels. The shorter day length signifies the water strider from the droplet of the impending temperature, also acting as a physical signal that the body uses to store lipids throughout the body as a food source. Air striders use these lipids to be metabolized during their hibernation. The length of hibernation depends on when the environment warms and the days become even longer.
Social behavior
Discrimination kin is rare in Gerridae, only really seen in Halobates . Without hunger playing a role, several studies have shown that both Aquarius remigis and Limnoporus dissortis parents tend to donibalize on non-relatives. Both species are very prevalent in American waters. This species shows no familial inclination, leaving their children to feed themselves. Females cannibalize more to young people than men and, in particular, to the first instar nymph. Young people should disperse as quickly as their wings are fully developed to avoid cannibalism and other territorial conflicts because neither the parents nor siblings can identify genetically related members with themselves.
Gerridae is a territorial insect and makes it known by its vibrational pattern. Gerridae adults and adult males have separate areas, although usually the male area is larger than the female. During the breeding season, the gamma will emit a warning vibration through the water and defend their territory and the women in it. Although gerridae is striking, making their presence known through expelling signals, they often live in large groups. These large groups usually form during the unmarried seasons because they do not have to compete. Instead of competing to reproduce, water striders can work together to get nutrition and shelter outside the breeding season. Air striders will try to disperse when these groups become overcrowded. They do it by flying or cannibalizing.
See also
- Veliidae (Strider water is smaller)
- Animal propulsion on the water surface
- The Denny Paradox
- List of Gerridae genera
References
External links
- "Gerridae". Integrated Taxonomic Information System.
- Large format images: winged and winged varieties
- Row, Row, Row Your Bug
- Water strider motion video
- Video Pond Skaters (Gerris lacustris) in Wales, England.
Source of the article : Wikipedia
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