Fly fishing is an angling method in which an artificial "fly" is used to catch fish. The fly is cast using a fly rod and specialized weighted line. Casting a nearly weightless fly or "lure" requires casting techniques different from other forms of casting. Fly fishermen use hand tied flies that resemble natural invertebrates, other food organisms, or "lures" to provoke the fish to strike. Fly fishing can be done in salt water. North Americans distinguish freshwater fishing between cold-water species and warm-water species, notably bass. In Britain, where natural water temperatures vary less, the distinction is between game fishing for trout and salmon versus coarse fishing for other species. Techniques for fly fishing differ with habitat Author Izaak Walton called fly fishing "The Contemplative Man's Recreation". In fly fishing, fish are caught by using artificial flies that are cast with a fly rod and a fly line; the fly line is heavy enough to send the fly to the target. The main difference between fly fishing and spin or bait fishing is that in fly fishing the weight of the line carries the hook through the air, whereas in spin and bait fishing the weight of the lure or sinker at the end of the monofilament or braided line gives casting distance.
Artificial flies are of several types. Flies can be made either to float or sink, range in size from a few millimeters to 30 cm long. Artificial flies are made by fastening hair, feathers, or other materials, both natural and synthetic, onto a hook; the first flies were tied with natural materials, but synthetic materials are now popular and prevalent. Flies are tied in sizes and patterns to match local terrestrial and aquatic insects, baitfish, or other prey attractive to the target fish species. Fly fishing is most renowned as a method for catching trout and salmon, but it is used for a wide variety of species including pike, bass and carp, as well as marine species, such as redfish, tarpon and striped bass. Many fly anglers catch unintended species such as chub and rudd while fishing for'main target' species such as trout. A growing population of anglers attempt to catch as many different species as possible with the fly. With the advancement of technology and development of stronger rods and reels, larger predatory saltwater species such as wahoo, tuna and sharks have become target species on fly.
Realistically any fish can be targeted and captured on fly as long as the main food source is replicated by the fly itself and suitable gear is used. Many credit the first recorded use of an artificial fly to the Roman Claudius Aelianus near the end of the 2nd century, he described the practice of Macedonian anglers on the Astraeus River:...they have planned a snare for the fish, get the better of them by their fisherman's craft.... They fasten red wool... round a hook, fit on to the wool two feathers which grow under a cock's wattles, which in color are like wax. Their rod is six feet long, their line is the same length, they throw their snare, the fish and maddened by the color, comes straight at it, thinking from the pretty sight to gain a dainty mouthful. In his book Fishing from the Earliest Times, William Radcliff gave the credit to Martial, born some two hundred years before Aelianus, who wrote:... Who has not seen the scarus rise and killed by fraudful flies... The last word, somewhat indistinct in the original, is either "mosco" or "musca" but catching fish with fraudulent moss seems unlikely.
The traditional Japanese method of fly-fishing is known as "Tenkara". Tenkara originated in the mountains of Japan as a way for professional fishermen and inn-keepers to harvest the local fish, Ayu and char for selling and providing a meal to their guests. A small-stream fishing method, preferred for being efficient, where the long rod allowed the fisherman to place the fly where the fish would be. Another style of fishing in Japan is Ayu fishing; as written by historian Andrew Herd, in the book "The Fly", "Fly fishing became popular with Japanese peasants from the twelfth century onward...fishing was promoted to a pastime worthy of Bushi, as part of an official policy to train the Bushi's mind during peacetime." This refers to Ayu fishing, which uses a fly as lure, uses longer rods, but there is no casting technique required, it's more similar to dapping. Ayu was practiced in the lowlands. Fishing flies are thought to have originated in Japan for Ayu fishing over 430 years ago; these flies were made with needles that were bent into shape and used as fishing hooks dressed as a fly.
The rods along with fishing flies, are considered to be a traditional local craft of the Kaga region. Although anglers in Scotland and Ireland had been fishing the lochs and loughs for trout with an artificial fly for several generations, the history of stillwater trout fishing in English reservoirs goes back little
The Plecoptera are an order of insects known as stoneflies. Some 3,500 species are described worldwide, with new species still being discovered. Stoneflies are found worldwide, except Antarctica. Stoneflies are believed to be one of the most primitive groups of Neoptera, with close relatives identified from the Carboniferous and Lower Permian geological periods, while true stoneflies are known from fossils only a bit younger; the modern diversity, however is of Mesozoic origin. Plecoptera are found in both the Southern and Northern Hemispheres, the populations are quite distinct, although the evolutionary evidence suggests species may have crossed the equator on a number of occasions before once again becoming geographically isolated. All species of Plecoptera are intolerant of water pollution, their presence in a stream or still water is an indicator of good or excellent water quality. Stoneflies have a generalized anatomy, with few specialized features compared to other insects, they have simple mouthparts with chewing mandibles, multiple-segmented antennae, large compound eyes, two or three ocelli.
The legs are robust, with each ending in two claws. The abdomen is soft, may include remnants of the nymphal gills in the adult. Both nymphs and adults have paired cerci projecting from the tip of their abdomens; the name "Plecoptera" means "braided-wings", from the Ancient Greek plekein and pteryx. This refers to the complex venation of their two pairs of wings, which are membranous and fold flat over their backs. Stoneflies are not strong fliers, some species are wingless. A few wingless species, such as the Lake Tahoe benthic stonefly or Baikaloperla, are the only known insects with the exception of Halobates, that are aquatic from birth to death; some true water bugs may be aquatic for their entire lives, but can leave the water to travel. The nymphs streams. A few species found in New Zealand and nearby islands have terrestrial nymphs, but these inhabit only moist environments; the nymphs physically resemble wingless adults, but have external gills, which may be present on any part of the body.
Nymphs can acquire oxygen via diffusing through the exoskeleton, or through gills located on behind the head, on the thorax, or around the anus. Due to their nymph's requirement for well oxygenated water, the species is sensitive to water pollution; this makes them important indicators for water quality. Most species are herbivorous as nymphs, feeding on submerged leaves and benthic algae, but many are hunters of other aquatic arthropods; the female can lay up to one thousand eggs. It will drop the eggs in the water, it may hang on a rock or branch. Eggs are covered in a sticky coating which allows them to adhere to rocks without being swept away by swifting moving currents; the eggs take two to three weeks to hatch, but some species undergo diapause, with the eggs remaining dormant throughout a dry season, hatching only when conditions are suitable. The insects remain in the nymphal form for one to four years, depending on species, undergo from 12 to 36 molts before emerging and becoming terrestrial as adults.
Before becoming adults, nymphs will leave the water, attach to a fixed surface and molt one last time. The adults only survive for a few weeks, emerge only during specific times of the year when resources are optimal; some do not feed at all. Adults are not strong fliers and stay near the stream or lake they hatched from. Traditionally, the stoneflies were divided into two suborders, the "Antarctoperlaria" and the Arctoperlaria. However, the former consists of the two most basal superfamilies of stoneflies, which do not seem to be each other's closest relatives. Thus, the "Antarctoperlaria" are not considered a natural group; the Arctoperlaria, have been divided into two infraorders, the Euholognatha and the Systellognatha. This corresponds to the phylogeny with one exception: the Scopuridae must be considered a basal family in the Arctoperlaria, not assignable to any of the infraorders. Alternatively, the Scopuridae were placed in an unranked clade "Holognatha" together with the Euholognatha, but the Scopuridae do not appear closer to the Euholognatha than to the Systellognatha.
In addition, not adopting the clades Antarctoperlaria and Holognatha allows for a systematic layout of the Plecoptera that adequately reproduces phylogeny, while retaining the traditional ranked taxa. Basal lineages Superfamily Eusthenioidea Family Diamphipnoidae Family Eustheniidae Superfamily Leptoperloidea Family Austroperlidae Family GripopterygidaeSuborder Arctoperlaria Basal family Scopuridae Infraorder Euholognatha Family Capniidae – small winter stoneflies Family Leuctridae – rolled-winged stoneflies Family Nemouridae – spring stoneflies Family Notonemouridae Family Taeniopterygidae – winter stoneflies Infraorder Systellognatha Family Chloroperlidae – green stoneflies Family Perlidae – common stoneflies Family Perlodidae Family Peltoperlidae – roachlike stoneflies Family Styloperlidae Family Pteronarcyidae – salmonflies, giant stoneflies Media related to Plecoptera at Wikimedia Commons Data related to Ple
Grasshoppers are a group of insects belonging to the suborder Caelifera. They are among what is the most ancient living group of chewing herbivorous insects, dating back to the early Triassic around 250 million years ago. Grasshoppers are ground-dwelling insects with powerful hind legs which allow them to escape from threats by leaping vigorously; as hemimetabolous insects, they do not undergo complete metamorphosis. At high population densities and under certain environmental conditions, some grasshopper species can change color and behavior and form swarms. Under these circumstances, they are known as locusts. Grasshoppers are plant-eaters, with a few species at times becoming serious pests of cereals and pasture when they swarm in their millions as locusts and destroy crops over wide areas, they protect themselves from predators by camouflage. Other species such as the rainbow grasshopper have warning coloration. Grasshoppers are affected by parasites and various diseases, many predatory creatures feed on both nymphs and adults.
The eggs are the subject of attack by predators. Grasshoppers have had a long relationship with humans. Swarms of locusts can have devastating effects and cause famine, in smaller numbers, the insects can be serious pests, they are used as food in countries such as Indonesia. They feature in art and literature. Grasshoppers belong to the suborder Caelifera. Although, "grasshopper" is sometimes used as a common name for the suborder in general, some sources restrict it to the more "advanced" groups, they may be placed in the infraorder Acrididea and have been referred-to as "short-horned grasshoppers" in older texts to distinguish them from the also-obsolete term "long-horned grasshoppers" with their much longer antennae. The phylogeny of the Caelifera, based on mitochondrial ribosomal RNA of thirty-two taxa in six out of seven superfamilies, is shown as a cladogram; the Ensifera Caelifera and all the superfamilies of grasshoppers except Pamphagoidea appear to be monophyletic. In evolutionary terms, the split between the Caelifera and the Ensifera is no more recent than the Permo-Triassic boundary.
The group diversified during the Triassic and have remained important plant-eaters from that time to now. The first modern families such as the Eumastacidae and Tridactylidae appeared in the Cretaceous, though some insects that might belong to the last two of these groups are found in the early Jurassic. Morphological classification is difficult because many taxa have converged towards a common habitat type; this information is not available from fossil specimens, the palaentological taxonomy is founded principally on the venation of the hindwings. The Caelifera includes about 11,000 known species. Many undescribed species exist in tropical wet forests; the Caelifera have a predominantly tropical distribution with fewer species known from temperate zones, but most of the superfamilies have representatives worldwide. They are exclusively herbivorous and are the oldest living group of chewing herbivorous insects; the most diverse superfamily is the Acridoidea, with around 8,000 species. The two main families in this are the Acrididae with a worldwide distribution, the Romaleidae, found chiefly in the New World.
The Ommexechidae and Tristiridae are South American, the Lentulidae and Pamphagidae are African. The Pauliniids are nocturnal and can swim or skate on water, the Lentulids are wingless. Pneumoridae are native to Africa southern Africa, are distinguished by the inflated abdomens of the males. Grasshoppers have the typical insect body plan of head and abdomen; the head is held vertically at an angle with the mouth at the bottom. The head bears a large pair of compound eyes which give all-round vision, three simple eyes which can detect light and dark, a pair of thread-like antennae that are sensitive to touch and smell; the downward-directed mouthparts are modified for chewing and there are two sensory palps in front of the jaws. The thorax and abdomen are segmented and have a rigid cuticle made up of overlapping plates composed of chitin; the three fused thoracic segments bear two pairs of wings. The forewings, known as tegmina, are narrow and leathery while the hindwings are large and membranous, the veins providing strength.
The legs are terminated by claws for gripping. The hind leg is powerful; the posterior edge of the tibia bears a double row of spines and there are a pair of articulated spurs near its lower end. The interior of the thorax houses the muscles that control the legs; the abdomen has eleven segments, the first of, fused to the thorax and contains the tympanal organ and hearing system. Segments two to eight are joined by flexible membranes. Segments nine to eleven are reduced in
Odonata is an order of carnivorous insects, encompassing the dragonflies and the damselflies. The Odonata form a clade. Dragonflies are larger, perch with their wings held out to the sides. Fabricius coined the term Odonata from the Ancient Greek ὀδών odṓn'tooth' because they have teeth on their mandibles though most insects have toothed mandibles; the word dragonfly is sometimes used to refer to all Odonata, but odonate is a more correct English name for the group as a whole. Odonata enthusiasts avoid ambiguity by using the term true dragonfly, or Anisopteran, when referring to just the Anisoptera; the term Warriorfly has been proposed. Some 5,900 species have been described in this order; this order has traditionally been grouped together with the mayflies and several extinct orders in a group called the "Paleoptera", but this grouping might be paraphyletic. What they do share with mayflies is the nature of how the wings are articulated and held in rest. In some treatments, the Odonata are understood in an expanded sense synonymous with the superorder Odonatoptera but not including the prehistoric Protodonata.
In this approach, instead of Odonatoptera, the term Odonatoidea is used. The systematics of the "Palaeoptera" are by no means resolved; the Anisoptera was long treated as a suborder, with a third suborder, the "Anisozygoptera". However, the combined suborder Epiprocta was proposed when it was found that the "Anisozygoptera" was paraphyletic, composed of extinct offshoots of dragonfly evolution; the four living species placed in that group are in the infraorder Epiophlebioptera, whereas the fossil taxa that were there are now dispersed about the Odonatoptera. World Odonata List considers Anisoptera as a suborder along with Zygoptera and Anisozygoptera as well-understood and preferred terms. Tarsophlebiidae is a prehistoric family of Odonatoptera that can be considered either a basal lineage of Odonata or their immediate sister taxon; the phylogenetic tree of the orders and suborders of odonates according to Bechly: The largest living odonate is the giant Central American helicopter damselfly Megaloprepus coerulatus with a wing span of 191 mm.
The heaviest living odonates are Tetracanthagyna plagiata with a wing span of 165 mm, Petalura ingentissima with a body length of 117 mm and wing span of 160 mm. The longest extant odonate is the Neotropical helicopter damselfly Mecistogaster linearis with a body length of 135 mm. Sometimes the giant Hawaiian darner Anax strenuus is claimed to be the largest living odonate with an alleged wing span of 190 mm, but this seems to be rather a myth as only 152 mm are scientifically documented. Odonata and their ancestors come from one of the oldest winged insect groups; the fossils of odonates and their cousins Paleozoic "giant dragonflies" like Meganeuropsis permiana from the Permian of North America with up to 71 cm wing span and 43 cm body length have been the largest insects of all times and belonged to the order Meganisoptera, the griffinflies, related to odonates but not part of the modern order Odonata in the restricted sense have one of the most complete records going back 319 million years ago.
The smallest living dragonfly is Nannophya pygmaea from east Asia, which a body length of 15 mm and a wing span of 20 mm, the smallest damselflies are species of the genus Agriocnemis with a wing span of only 17–18 mm. These insects characteristically have large rounded heads covered by well-developed, compound eyes, legs that facilitate catching prey in flight, two pairs of long, transparent wings that move independently, elongated abdomens, they have short antennae. The mouthparts include simple chewing mandibles in the adult. Flight in the Odonata is direct, with flight muscles attaching directly to the wings; this allows active control of the amplitude, angle of attack and twist of each of the four wings independently. In most families there is a structure on the leading edge near the tip of the wing called the pterostigma; this is a thickened, hemolymph–filled and colorful area bounded by veins. The functions of the pterostigma are not known, but it most has an aerodynamic effect and may have a visual function.
More mass at the end of the wing may reduce the energy needed to move the wings up and down. The right combination of wing stiffness and wing mass could reduce the energy consumption of flying. A pterostigma is found among other insects, such as bees; the nymphs have stockier, bodies than the adults. In addition to lacking wings, their eyes are smaller, their antennae longer, their heads are less mobile than in the adult, their mouthparts are modified, with the labium being adapted into a unique prehensile organ for grasping prey. Damselfly nymphs breathe through external gills on the abdomen, while dragonfly nymphs respire through an organ in their rectum. Although generally
Cockroaches are insects of the order Blattodea, which includes termites. About 30 cockroach species out of 4,600 are associated with human habitats. About four species are well known as pests; the cockroaches are an ancient group, dating back at least as far as the Carboniferous period, some 320 million years ago. Those early ancestors however lacked the internal ovipositors of modern roaches. Cockroaches are somewhat generalized insects without special adaptations like the sucking mouthparts of aphids and other true bugs, they are common and hardy insects, can tolerate a wide range of environments from Arctic cold to tropical heat. Tropical cockroaches are much bigger than temperate species, contrary to popular belief, extinct cockroach relatives and'roachoids' such as the Carboniferous Archimylacris and the Permian Apthoroblattina were not as large as the biggest modern species; some species, such as the gregarious German cockroach, have an elaborate social structure involving common shelter, social dependence, information transfer and kin recognition.
Cockroaches have appeared in human culture since classical antiquity. They are popularly depicted as dirty pests, though the great majority of species are inoffensive and live in a wide range of habitats around the world. Cockroaches are members of the order Blattodea, which includes the termites, a group of insects once thought to be separate from cockroaches. 4,600 species and over 460 genera are described worldwide. The name "cockroach" comes from the Spanish word for cockroach, transformed by 1620s English folk etymology into "cock" and "roach"; the scientific name derives from the Latin blatta, "an insect that shuns the light", which in classical Latin was applied not only to cockroaches, but to mantids. The name Blattaria was used interchangeably with the name Blattodea, but whilst the former name was used to refer to'true' cockroaches the latter includes the termites; the current catalogue of world cockroach species uses the name Blattodea for the group. Another name, Blattoptera, is sometimes used.
The earliest cockroach-like fossils are from the Carboniferous period 320 million years ago, as are fossil roachoid nymphs. Since the 19th century, scientists believed that cockroaches were an ancient group of insects that had a Devonian origin, according to one hypothesis. Fossil roachoids that lived during that time differ from modern cockroaches in having long external ovipositors and are the ancestors of mantises, as well as modern blattodeans; as the body, hind wings and mouthparts are not preserved in fossils the relationship of these roachoids and modern cockroaches remains disputed. The first fossils of modern cockroaches with internal ovipositors appeared in the early Cretaceous. A recent phylogenetic analysis suggests; the evolutionary relationships of the Blattodea shown in the cladogram are based on Eggleton, Beccaloni & Inward. The cockroach families Lamproblattidae and Tryonicidae are not shown but are placed within the superfamily Blattoidea; the cockroach families Corydiidae and Ectobiidae were known as the Polyphagidae and Blattellidae.
Termites were regarded as a separate order Isoptera to cockroaches. However, recent genetic evidence suggests that they evolved directly from'true' cockroaches, many authors now place them as an "epifamily" of Blattodea; this evidence supported a hypothesis suggested in 1934 that termites are related to the wood-eating cockroaches. This hypothesis was based on similarity of the symbiotic gut flagellates in termites regarded as living fossils and wood-eating cockroaches. Additional evidence emerged when F. A. McKittrick noted similar morphological characteristics between some termites and cockroach nymphs; the similarities among these cockroaches and termites have led some scientists to reclassify termites as a single family, the Termitidae, within the order Blattodea. Other scientists have taken a more conservative approach, proposing to retain the termites as the Termitoidea, an epifamily within the order; such measure preserves the classification of termites at family level and below. Most species of cockroach are about the size of a thumbnail.
The world's heaviest cockroach is the Australian giant burrowing cockroach Macropanesthia rhinoceros, which can reach 9 cm in length and weigh more than 30 g. Comparable in size is the Central American giant cockroach Blaberus giganteus, which grows to a similar length; the longest cockroach species is Megaloblatta longipennis, which can reach 97 mm in length and 45 mm across. A Central and South American species, Megaloblatta blaberoides, has the largest wingspan of up to 185 mm. Cockroaches are generalized insects, with few special adaptations, may be among the most primitive living neopteran insects, they have a small head and a broad, flattened body, most species are reddish-brown to dark brown. They have large compound eyes, two ocelli, long, flexible antennae; the mouthparts are on the underside of the head and include generalized chewing mandibles, salivary glands and various touch and taste receptors. The body is divided into a thorax of a ten-segmented abdomen; the external surface has a tough exoskeleton which contains calcium carbonate and protects the inner organs and provides attachment to muscles.
It is coated with wax to repel water. The wings are attached to the third thoracic segments; the tegmina, or fir
Invertebrates are animals that neither possess nor develop a vertebral column, derived from the notochord. This includes all animals apart from the subphylum Vertebrata. Familiar examples of invertebrates include arthropods, mollusks and cnidarians; the majority of animal species are invertebrates. Many invertebrate taxa have a greater number and variety of species than the entire subphylum of Vertebrata; some of the so-called invertebrates, such as the Tunicata and Cephalochordata are more related to the vertebrates than to other invertebrates. This makes the invertebrates paraphyletic, so the term has little meaning in taxonomy; the word "invertebrate" comes from the Latin word vertebra, which means a joint in general, sometimes a joint from the spinal column of a vertebrate. The jointed aspect of vertebra is derived from the concept of turning, expressed in the root verto or vorto, to turn; the prefix in- means "not" or "without". The term invertebrates is not always precise among non-biologists since it does not describe a taxon in the same way that Arthropoda, Vertebrata or Manidae do.
Each of these terms describes a valid taxon, subphylum or family. "Invertebrata" is a term of convenience, not a taxon. The Vertebrata as a subphylum comprises such a small proportion of the Metazoa that to speak of the kingdom Animalia in terms of "Vertebrata" and "Invertebrata" has limited practicality. In the more formal taxonomy of Animalia other attributes that logically should precede the presence or absence of the vertebral column in constructing a cladogram, for example, the presence of a notochord; that would at least circumscribe the Chordata. However the notochord would be a less fundamental criterion than aspects of embryological development and symmetry or bauplan. Despite this, the concept of invertebrates as a taxon of animals has persisted for over a century among the laity, within the zoological community and in its literature it remains in use as a term of convenience for animals that are not members of the Vertebrata; the following text reflects earlier scientific understanding of the term and of those animals which have constituted it.
According to this understanding, invertebrates do not possess a skeleton of bone, either internal or external. They include hugely varied body plans. Many have like jellyfish or worms. Others have outer shells like those of insects and crustaceans; the most familiar invertebrates include the Protozoa, Coelenterata, Nematoda, Echinodermata and Arthropoda. Arthropoda include insects and arachnids. By far the largest number of described invertebrate species are insects; the following table lists the number of described extant species for major invertebrate groups as estimated in the IUCN Red List of Threatened Species, 2014.3. The IUCN estimates that 66,178 extant vertebrate species have been described, which means that over 95% of the described animal species in the world are invertebrates; the trait, common to all invertebrates is the absence of a vertebral column: this creates a distinction between invertebrates and vertebrates. The distinction is one of convenience only. Being animals, invertebrates are heterotrophs, require sustenance in the form of the consumption of other organisms.
With a few exceptions, such as the Porifera, invertebrates have bodies composed of differentiated tissues. There is typically a digestive chamber with one or two openings to the exterior; the body plans of most multicellular organisms exhibit some form of symmetry, whether radial, bilateral, or spherical. A minority, exhibit no symmetry. One example of asymmetric invertebrates includes all gastropod species; this is seen in snails and sea snails, which have helical shells. Slugs appear externally symmetrical. Other gastropods develop external asymmetry, such as Glaucus atlanticus that develops asymmetrical cerata as they mature; the origin of gastropod asymmetry is a subject of scientific debate. Other examples of asymmetry are found in hermit crabs, they have one claw much larger than the other. If a male fiddler loses its large claw, it will grow another on the opposite side after moulting. Sessile animals such as sponges are asymmetrical alongside coral colonies. Neurons differ in invertebrates from mammalian cells.
Invertebrates cells fire in response to similar stimuli as mammals, such as tissue trauma, high temperature, or changes in pH. The first invertebrate in which a neuron cell was identified was the medicinal leech, Hirudo medicinalis. Learning and memory using nociceptors in the sea hare, Aplysia has been described. Mollusk neurons are able to detect tissue trauma. Neurons have been identified in a wide range of invertebrate species, including annelids, molluscs and arthropods. One type of invertebrate respi
Damselflies are insects of the suborder Zygoptera in the order Odonata. They are similar to dragonflies, which constitute the other odonatan suborder, but are smaller, have slimmer bodies, most species fold the wings along the body when at rest. An ancient group, damselflies have existed since at least the Lower Permian, are found on every continent except Antarctica. All damselflies are predatory; the nymphs are aquatic, with different species living in a variety of freshwater habitats including acid bogs, ponds and rivers. The nymphs moult at the last moult climbing out of the water to undergo metamorphosis; the skin splits down the back, they emerge and inflate their wings and abdomen to gain their adult form. Their presence on a body of water indicates that it is unpolluted, but their dependence on freshwater makes them vulnerable to damage to their wetland habitats; some species of damselfly have elaborate courtship behaviours. Many species are sexually dimorphic, the males being more brightly coloured than the females.
Like dragonflies, they reproduce using delayed fertilisation. A mating pair form a shape known as a "heart" or "wheel", the male clasping the female at the back of the head, the female curling her abdomen down to pick up sperm from secondary genitalia at the base of the male's abdomen; the pair remain together with the male still clasping the female while she lays eggs within the tissue of plants in or near water using a robust ovipositor. Fishing flies. Damselflies sometimes provide the subject for personal jewellery such as brooches; the Zygoptera are an ancient group, with fossils known from the lower Permian, at least 250 million years ago. All the fossils of that age are of adults, similar in structure to modern damselflies, so it is not known whether their larvae were aquatic at that time; the earliest larval odonate. Fossils of damselfly-like Protozygoptera date back further to 311–30 Mya. Well-preserved Eocene damselfly larvae and exuviae are known from fossils preserved in amber in the Baltic region.
Molecular analysis in 2013 confirms that most of the traditional families are monophyletic, but shows that the Amphipterygidae, Megapodagrionidae and Protoneuridae are paraphyletic and will need to be reorganised. The Protoneuridae in particular is shown to be composed of six clades from five families; the result so far is 27 damselfly families, with 7 more to be created. The discovered clades did not agree well with traditional characteristics used to classify living and fossil Zygoptera such as wing venation, so fossil taxa will need to be revisited; the 18 extant traditional families are provisionally rearranged as follows: Dashed lines indicate unresolved relationships. The general body plan of a damselfly is similar to that of a dragonfly; the compound eyes are large but are more separated and smaller than those of a dragonfly. Above the eyes is the frons or forehead, below this the clypeus, on the upper lip the labrum, an extensible organ used in the capture of prey; the top of the head bears three simple eyes, which may measure light intensity, a tiny pair of antennae that serve no olfactory function but may measure air speed.
Many species are sexually dimorphic. For example, in Coenagrion, the Eurasian bluets, the males are bright blue with black markings, while the females are predominantly green or brown with black. A few dimorphic species show female-limited polymorphism, the females being in two forms, one form distinct and the other with the patterning as in males; the ones that look like males, are under a third of the female population but the proportion can rise and a theory that explains this response suggests that it helps overcome harassment by males. Some Coenagrionid damselflies show male-limited polymorphism, an less understood phenomenon. In general, damselflies are smaller than dragonflies, the smallest being members of the genus Agriocnemis. However, members of the Pseudostigmatidae are exceptionally large for the group, with wingspans as much as 19 cm in Megaloprepus and body length up to 13 cm in Pseudostigma aberrans; the first thoracic segment is the prothorax. The joint between head and prothorax is slender and flexible, which enables the damselfly to swivel its head and to manoeuvre more when flying.
The remaining thoracic segments are the fused mesothorax and metathorax, each with a pair of wings and a pair of legs. A dark stripe known as the humeral stripe runs from the base of the front wings to the second pair of legs, just in front of this is the pale-coloured, antehumeral stripe; the forewings and hindwings are similar in appearance and are membranous, being strengthened and supported by longitudinal veins that are linked by many cross-veins and that are filled with haemolymph. Species markers include quadrangular markings on the wings known as the pterostigma or stigma, in all species, there is a nodus near the leading edge; the thorax houses the flight muscles. Many damselflies have clear wings, but some have coloured wings, whether uniformly suffused with colour or boldly marked with a coloured patch. In species such as the banded demoiselle, Calopteryx splendens the males have both a d