Stridulation is the act of producing sound by rubbing together certain body parts. This behavior is mostly associated with insects, but other animals are known to do this as well, such as a number of species of fish, snakes and spiders. The mechanism is typically that of one structure with a well-defined lip, ridge, or nodules (the "scraper" or plectrum) being moved across a finely-ridged surface (the "file" or stridulitrum—sometimes called the pars stridens) or vice versa, and vibrating as it does so, like the dragging of a phonograph needle across a vinyl record. Sometimes it is the structure bearing the file which resonates to produce the sound, but in other cases it is the structure bearing the scraper, with both variants possible in related groups. [1] Common onomatopoeic words for the sounds produced by stridulation include chirp and chirrup.
Insects and other arthropods stridulate by rubbing together two parts of the body. These are referred to generically as the stridulatory organs.
The mechanism is best known in crickets, mole crickets, and grasshoppers, but other insects which stridulate include Curculionidae (weevils and bark beetles), Cerambycidae (longhorned beetles), [2] Mutillidae ("velvet ants"), Reduviidae (assassin bugs), Buprestidae (metallic wood-boring beetles), Hydrophilidae (water scavenger beetles), [3] Cicindelinae (tiger beetles), Scarabaeidae (scarab beetles), [2] Glaresidae ("enigmatic scarabs"), larval Lucanidae (stag beetles), [4] Passalidae (Bessbugs), [2] Geotrupidae (earth-boring dung beetles), Alydidae (broad-headed bugs), [5] Largidae (bordered plant bugs), [6] Miridae (leaf bugs), Corixidae (water boatmen, notably Micronecta scholtzi ), various ants (including the Black imported fire ant, Solenopsis richteri ), [7] some stick insects such as Pterinoxylus spinulosus , [8] and some species of Agromyzidae (leaf-mining flies). While cicadas are well-known for sound production via abdominal tymbal organs, it has been demonstrated that some species can produce sounds via stridulation, as well. [9]
Stridulation is also known in a few tarantulas (Arachnida), certain centipedes, such as Scutigera coleoptrata , and some pill millipedes (Diplopoda, Oniscomorpha). [10] It is also widespread among decapod crustaceans, e.g., rock lobsters. [11] Most spiders are silent, but some tarantula species are known to stridulate. When disturbed, Theraphosa blondi , the Goliath tarantula, can produce a rather loud hissing noise by rubbing together the bristles on its legs. This is said to be audible to a distance of up to 15 feet (4.5 m). [12] One of the wolf spiders, Schizocosa stridulans , produces low-frequency sounds by flexing its abdomen (tremulation, rather than stridulation) or high-frequency stridulation by using the cymbia on the ends of its pedipalps. [13] In most species of spiders, stridulation commonly occurs by males during sexual encounters. In the species Holocnemus pluchei , females also possess stridulatory organs, and both sexes engage in stridulation. [14] In the species Steatoda nobilis, the males produce stridulation sounds during mating. [15]
The anatomical parts used to produce sound are quite varied: the most common system is that seen in grasshoppers and many other insects, where a hind leg scraper is rubbed against the adjacent forewing (in beetles and true bugs the forewings are hardened); in crickets and katydids a file on one wing is rubbed by a scraper on the other wing; in longhorned beetles, the back edge of the pronotum scrapes against a file on the mesonotum; in various other beetles, the sound is produced by moving the head—up/down or side-to-side—while in others the abdominal tergites are rubbed against the elytra; in assassin bugs, the tip of the mouthparts scrapes along a ridged groove in the prosternum; in velvet ants the back edge of one abdominal tergite scrapes a file on the dorsal surface of the following tergite.
Stridulation in several of these examples is for attracting a mate, or as a form of territorial behaviour, but can also be a warning signal (acoustic aposematism, as in velvet ants and tarantulas). This kind of communication was first described by Slovenian biologist Ivan Regen (1868–1947).
Some species of venomous snakes stridulate as part of a threat display. They arrange their body into a series of parallel C-shaped (counterlooped) coils that they rub together to produce a sizzling sound, rather like water on a hot plate. The best-known examples are members of the genus Echis (saw-scaled vipers), although those of the genus Cerastes (North African desert vipers) and at least one bush viper species, Atheris desaixi , do this as well. [16] [17] A bird species, the club-winged manakin, has a dedicated stridulation apparatus, while a species of mammal, the lowland streaked tenrec, (Hemicentetes semispinosus) produces a high-pitched noise by rubbing together specialised quills on its back. [18]
Insects in the family Tettigoniidae are commonly called katydids or bush crickets. They have previously been known as "long-horned grasshoppers". More than 8,000 species are known. Part of the suborder Ensifera, the Tettigoniidae are the only extant (living) family in the superfamily Tettigonioidea.
The Mutillidae are a family of more than 7,000 species of wasps whose wingless females resemble large, hairy ants. Their common name velvet ant refers to their resemblance to an ant, and their dense pile of hair, which most often is bright scarlet or orange, but may also be black, white, silver, or gold. Their bright colors serve as aposematic signals. They are known for their extremely painful stings,, and has resulted in the common name "cow killer" or "cow ant" being applied to the species Dasymutilla occidentalis. However, mutillids are not aggressive and sting only in defense. In addition, the actual toxicity of their venom is much lower than that of honey bees or harvester ants. Unlike true ants, they are solitary, and lack complex social systems.
Passalidae is a family of beetles known variously as "bessbugs", "bess beetles", "betsy beetles" or "horned passalus beetles". Nearly all of the 500-odd species are tropical; species found in North America are notable for their size, ranging from 20 to 43 mm, for having a single "horn" on the head, and for a form of social behavior unusual among beetles.
Urticating hairs or urticating bristles are one of the primary defense mechanisms used by numerous plants, almost all New World tarantulas, and various lepidopteran caterpillars. Urtica is Latin for "nettle", and bristles that urticate are characteristic of this type of plant, and many other plants in several families. This term also refers to certain types of barbed bristles that cover the dorsal and posterior surface of a tarantula's or caterpillar's abdomen. Many tarantula species eject bristles from their abdomens, directing them toward potential attackers. These bristles can embed themselves in the other animal's skin or eyes, causing physical irritation, usually to great discomfort. The term "hairs" is technically a misnomer, as only mammals possess true hairs. The scientific term for plant hairs is trichomes.
The Goliath birdeater belongs to the tarantula family Theraphosidae. Found in northern South America, it is the largest spider in the world by mass and body length, and second to the giant huntsman spider by leg span. It is also called the Goliath tarantula or Goliath bird-eating spider; the practice of calling theraphosids "bird-eating" derives from an early 18th-century copper engraving by Maria Sibylla Merian that shows one eating a hummingbird. Despite the spider's name, it rarely preys on birds.
Hydrophilidae, also known colloquially as water scavenger beetles, is a family of beetles. Aquatic hydrophilids are notable for their long maxillary palps, which are longer than their antennae. Several of the former subfamilies of Hydrophilidae have recently been removed and elevated to family rank; Epimetopidae, Georissidae, Helophoridae, Hydrochidae, and Spercheidae. While the majority of hydrophilids are aquatic, around a third of described species are terrestrial, mostly belonging to the subfamily Sphaeridiinae.
Grasshoppers are a group of insects belonging to the suborder Caelifera. They are amongst what are possibly the most ancient living groups of chewing herbivorous insects, dating back to the early Triassic around 250 million years ago.
A tergum is the dorsal ('upper') portion of an arthropod segment other than the head. The anterior edge is called the 'base' and posterior edge is called the 'apex' or 'margin'. A given tergum may be divided into hardened plates or sclerites commonly referred to as tergites.
Deinacrida fallai or the Poor Knights giant wētā is a species of insect in the family Anostostomatidae. It is endemic to the Poor Knights Islands off northern New Zealand. D. fallai are commonly called giant wētā due to their large size. They are one of the largest insects in the world, with a body length measuring up to 73 mm. Their size is an example of island gigantism. They are classified as vulnerable by the IUCN due to their restricted distribution.
Tarantulas comprise a group of large and often hairy spiders of the family Theraphosidae. As of December 2023, 1,100 species have been identified, with 166 genera. The term "tarantula" is usually used to describe members of the family Theraphosidae, although many other members of the same infraorder (Mygalomorphae) are commonly referred to as "tarantulas" or "false tarantulas". Some of the more common species have become popular in the exotic pet trade. Many New World species kept as pets have setae known as urticating hairs that can cause irritation to the skin, and in extreme cases, cause damage to the eyes.
Pelinobius or the king baboon is a monotypic genus of east African tarantulas containing the single species, Pelinobius muticus. It was first described by Ferdinand Anton Franz Karsch in 1885, and is found in Tanzania and Kenya.
Insects are hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body, three pairs of jointed legs, compound eyes, and a pair of antennae. Insects are the most diverse group of animals, with more than a million described species; they represent more than half of all animal species.
Theraphosa apophysis is a species of spider in the family Theraphosidae, found in Venezuela, Colombia and Brazil.
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Omocestus viridulus, known in the British Isles as the common green grasshopper, is a Palearctic species of grasshopper in the subfamily Gomphocerinae.
Panoploscelis is a genus of very large insects belonging to the true katydid tribe Eucocconotini, which is a subfamily of the Tettigoniidae. Like the other members of the suborder Ensifera, Panoploscelis are part of the insect order Orthoptera, which also contains crickets, grasshoppers and locusts. Members of this genus are among the largest katydids of the Neotropics.
Grylloidea is the superfamily of insects, in the order Orthoptera, known as crickets. It includes the "true crickets", scaly crickets, wood crickets and other families, some only known from fossils.
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Pterinoxylus spinulosus is a species of stick insect found in the Neotropics. It was first described by the Austrian entomologist Ludwig Redtenbacher in 1908, from an adult male and an immature female. It was not until 1957 that an adult female was described by J.A.G. Rehn.
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