Common Darter — British Dragonfly Society
Common Darter
Description
The most common species of Darter that can be found well into November.
Males: bright orange-red.
Immature males: Pale, yellowish-brown, similar females.
Females: pale, yellowish-brown abdomen often developing red markings with age.
Where to See
| Latin Name | Sympetrum striolatum |
|---|---|
| Habitat | |
| Status & Distribution | Worldwide |
| Number of Families | |
| Number of Species |
Life History & EcologyDragonflies and damselflies are predaceous both as immatures and adults. The adults are quick, agile fliers that are generally considered beneficial because they feed on large numbers of small, flying insects like gnats and mosquitos. Legs are used either as a basket for catching prey or as grapples for clinging to emergent vegetation. Eggs are laid singly in fresh water; females often hover over open water and dip their abdomen as they oviposit. Eggs hatch into aquatic immatures (naiads) that feed opportunistically on other forms of aquatic life including mayfly naiads, small crustaceans, annelids, and mollusks. Some of the large dragonfly naiads will even attack small fish and tadpoles. All immature Odonata have a specialized labium for catching prey. Folded under the head and thorax when not in use, the labium can be extended rapidly toward potential prey. Hooked lobes at the tip of the labium grasp or impale the prey and draw it back to the mouth as the labium retracts. Damselfly naiads are usually more slender than dragonfly naiads and have three leaf-like gills at the end of the abdomen. Dragonfly gills are located internally, within the rectum, where bellows-like contractions of the rectal muscles cause oxygenated water to circulate in and out. Physical FeaturesDragonflies
Immatures:
Adults:
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Damselflies
Immatures:
Adults:
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Economic Importance
Most dragonflies and damselflies are regarded as beneficial insects because they feed on small flying insects such as mosquitoes. They may also catch and eat honey bees — then they are regarded as pests by the beekeepers.
In some parts of Europe, dragonflies are considered a threat to the poultry industry because they transmit Prosthogoniums pellucidus,a parasitic flatworm. Dragonfly naiads become infected by ingesting cysts of the flatworm. These cysts survive into adulthood of the dragonfly and may spread to birds (particularly poultry) that catch and eat the adult dragonflies. The flatworm cysts dissolve in the bird’s intestine and infection spreads into the cloaca and reproductive organs. The Dutch have a maxim: «Hide the hens, the dragonflies are coming.»
Major Families
- Aeshnidae (Darners) — These insects are notable for their large size and brilliant blue or green coloration. Includes the common green darner (Anax junius).
- Libellulidae (Common Skimmers) — This is the largest family in the order. It contains many species with dark spots on the wings.
- Gomphidae (Clubtails) — These dragonflies have the terminal abdominal segments swollen, hence the common name.
- Calopterygidae (Broadwinged Damselflies) — The wings of these insects are shaped like the seeds of a maple tree.
- Coenagrionidae (Narrowwinged Damselflies) — Small, delicate insects. The body is usually black with blue markings. At rest, the wings are held together over the back.
- Lestidae (Spreadwinged Damselflies) — These damselflies rest with the body nearly vertical and the wings partly outspread.
Bug Bytes
- The compound eyes of some dragonflies may have up to 28,000 facets.
- Some naiads can shoot out their labium and catch prey in only 25 milliseconds.
- Scientists have documented large-scale migrations of dragonflies. One swarm was observed 1,400 km off the coast of Australia.
- Some immature damselflies establish feeding territories, areas that are defended against invasion by other conspecifics. Territorial species develop more rapidly and produce larger adults than other non-territorial species.
- Many adult male dragonflies establish and defend territories along the perimeter of a lake or stream. Females will mate only with males that hold a territory, so population density is somewhat regulated by territory size.
- Male Odonata have claspers at the end of their abdomen, but no external genitalia. Before finding a mate, a male attaches a spermatophore to his second abdominal segment. He then grabs a female around the neck with his claspers and she retrieves the spermatophore with the genital opening of her abdomen.
- Most dragonfly naiads can move forward by «jet propulsion». Rapid contraction of the rectal muscles forces water out the rear end and shoots the insect forward.
- Male damselflies (and perhaps some dragonflies) have a special flagellum associated with the copulatory organ that can reach into a female’s body and remove sperm deposited by another male in a previous mating.
- Dragonflies are known by many interesting common names, including «snake doctors», «devil’s darning needles», and «mosquito hawks».
© 2020 by John R. Meyer
Last Updated: 23 January 2020
projects.ncsu.edu
Common frog facts for kids
Linnaeus, 1758
- R. t. temporaria
- R. t. honnorati
- R. t. parvipalmata
The common frog (Rana temporaria), also known as the European common frog, European common brown frog, or European grass frog, is a semi-aquatic amphibian of the family Ranidae, found throughout much of Europe as far north as Scandinavia and as far east as the Urals. The farthest west it can be found is Ireland, where it has long been thought, erroneously, to be an entirely introduced species. They are also found in Asia, and eastward to Japan.
Common frogs metamorphose through three distinct developmental life stages — aquatic larva, terrestrial juvenile, and adult. They have corpulent bodies with a rounded snout, webbed feet and long hind legs adapted for swimming in water and hopping on land. Common frogs are often confused with the common toad Bufo bufo, but frogs can easily be distinguished as they have longer legs, hop, and have a moist skin, whereas toads crawl and have a dry ‘warty’ skin.
Contents
Description
The adult common frog has a body length of 6 to 9 centimetres (2.4 to 3.5 in) its back and flanks varying in colour from olive green to grey-brown, brown, olive brown, grey, yellowish and rufous. However, can lighten and darken its skin to match its surroundings. Some individuals have more unusual colouration — both black and red individuals have been found in Scotland, and albino frogs have been found with yellow skin and red eyes. During the mating season the male common frog tends to turn greyish-blue. The average weight is 22.7 g (0.80 oz); the female is usually slightly larger than the male.
The flanks, limbs and backs are covered with irregular dark blotches and they usually sport a chevron-shaped spot on the back of their neck and a dark spot behind the eye. Unlike other amphibians, common frogs generally lack a mid-dorsal band but, when they have one, it is comparatively faint. In many countries moor frogs have a light dorsal band which easily distinguishes them from common frogs.
The underbelly is white or yellow (occasionally more orange in females) and can be speckled with brown or orange. The eyes are brown with transparent horizontal pupils, and they have transparent inner eyelids to protect the eyes while underwater, as well as a ‘mask’ which covers the eyes and eardrums. Although the common frog has long hind legs compared to the common toad, they are shorter than those of the agile frog with which it shares some of its range. The longer hind legs and fainter colouration of the agile frog are the main features that distinguish the two species.
Males are distinguishable from females as they are smaller and have hard swellings, known as nuptial pads, on the first digits of the forelegs, used for gripping females during mating. During the mating season males’ throats often turn white, and their overall colour is generally light and grayish, whereas the female is browner, or even red.
Distribution
The common frog is found throughout much of Europe as far north as northern Scandinavia inside the Arctic Circle and as far east as the Urals, except for most of Iberia, southern Italy, and the southern Balkans. Other areas where the common frog has been introduced include the Isle of Lewis, Shetland, Orkney and the Faroe Islands. It is also found in Asia, and eastward to Japan.
The common frog has long been thought to be an entirely introduced species in Ireland, however, genetic analyses suggest that particular populations in the south west of Ireland are indeed indigenous to the country. The authors propose that the Irish frog population is a mixed group that includes native frogs that survived the last glacial period in ice free refugia, natural post-glacial colonisers and recent artificial introductions from Western Europe.
Newly hatched tadpoles are mainly herbivorous, feeding on algae, detritus, plants and some small invertebrates, but they become fully carnivorous once their back legs develop, feeding on nimals or even other tadpoles when food is scarce. Juvenile frogs feed on invertebrates both on land and in water but their feeding habits change significantly throughout their lives and older frogs will eat only on land. Adult common frogs will feed on any invertebrate of a suitable size, catching their prey on their long, sticky tongues, although they do not feed at all during the short breeding season. Preferred foods include insects (especially flies), snails, slugs and worms.
Habitat and habits
Outside the breeding season, common frogs live a solitary life in damp places near ponds or marshes or in long grass. They are normally active for much of the year, only hibernating in the coldest months. In the most northern extremities of their range they may be trapped under ice for up to nine months of the year, but recent studies have shown that in these conditions they may be relatively active at temperatures close to freezing. Common frogs hibernate in running waters, muddy burrows, or in layers of decaying leaves and mud at the bottom of ponds. The oxygen uptake through the skin suffices to sustain the needs of the cold and motionless frogs during hibernation.
Reproduction
During the spring the frog’s pituitary gland is stimulated by changes in external factors, such as rainfall, day length and temperature, to produce hormones which, in turn, stimulate the production of — eggs in the females and sperm in the male. The male’s nuptial pad also swells and becomes more heavily pigmented. Common frogs breed in shallow, still, fresh water such as ponds, with spawning commencing sometime between March and late June, but generally in April over the main part of their range. The adults congregate in the ponds, where the males compete for females. The courtship ritual involves noisy vocalizations, known as «croaking», by large numbers of males. The females are attracted to the males that produce the loudest and longest calls.
Conservation status
Common frogs are susceptible to a number of diseases, including Ranavirus and the parasitic fungus Batrachochytrium dendrobatidis which has been implicated in extinctions of amphibian species around the world. Loss of habitat and the effect of these diseases has caused the decline of populations across Europe in recent years. The common frog is listed as a species of least concern on the IUCN Red List of Threatened Species.
Predators
Tadpoles are eaten by fish, beetles, dragonfly larvae and birds. Adult frogs have many predators including storks, birds of prey, crows, gulls, ducks, terns, herons, pine martens, stoats, weasels, polecats, badgers, otters and snakes. Some frogs are killed, but rarely eaten, by domestic cats, and large numbers are killed on the roads by motor vehicles.
Images for kids
Common Frog in Norway
European Common Frog or European Common Brown Frog
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