An ozopore is the opening of a defensive

gland In animals, a gland is a group of cells in an animal's body that synthesizes substances (such as hormones) for release into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland). Structure De ...

present in some arthropods, notably in

millipede Millipedes are a group of arthropods that are characterised by having two pairs of jointed legs on most body segments; they are known scientifically as the class Diplopoda, the name derived from this feature. Each double-legged segment is a resu ...

s of the order

Polydesmida Polydesmida (from the Greek language, Greek ''poly'' "many" and ''desmos'' "bond") is the largest order (biology), order of millipedes, containing approximately 3,500 species, including all the millipedes reported to produce hydrogen cyanide (HCN ...

Ozopore.
External Anatomy of Polydesmida. polydesmida.info and in

harvestmen The Opiliones (formerly Phalangida) are an order of arachnids colloquially known as harvestmen, harvesters, harvest spiders, or daddy longlegs. , over 6,650 species of harvestmen have been discovered worldwide, although the total number of ext ...

, the eight-legged arachnids also known as "daddy long-legs". The glands themselves are known as ozadenes, also called "scent glands", "repugnatorial glands", "odoriferous glands" or "stink glands" by various authors. The name is derived from

Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...

''ozo'' "smell" and

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

''porus'' "pore, small opening".

Harvestmen

In harvestmen, ozopores are located at the anterior sides of the

prosoma The cephalothorax, also called prosoma in some groups, is a tagma of various arthropods, comprising the head and the thorax fused together, as distinct from the abdomen behind. (The terms ''prosoma'' and ''opisthosoma'' are equivalent to ''cepha ...

. The defensive secretions emitted also act as an alarm

pheromone A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...

. The glands are infoldings of the body wall, consisting of three layers. Although the glands themselves have no musculature, there is associated musculature present, which is most elaborate in the harvestman suborder

Cyphophthalmi Cyphophthalmi is a suborder of harvestmen, colloquially known as mite harvestmen. Cyphophthalmi comprises 36 genera, and more than two hundred described species. The six families are currently grouped into three infraorders: the Boreophthalmi, Sc ...

Eupnoi The Eupnoi are a suborder of harvestmen, with more than 200 genera, and about 1,700 described species. They consist of two superfamilies, the Phalangioidea with many long-legged species common to northern temperate regions, and the small group C ...

and

Dyspnoi Dyspnoi is a suborder of harvestmen, currently comprising 43 extant genera and 356 extant species, although more species are expected to be described in the future. The eight families are currently grouped into three superfamilies: the Acropsopil ...

have the most reduced muscular system. (2007): Defensive Mechanisms. In: Pinto-da-Rocha ''et al.'' 2007: 382ffPinto-da-Rocha ''et al.'' 2007: 382ff This defensive behavior is considered most effective in the suborders Cyphophthalmi and

Laniatores Laniatores is the largest suborder of the arachnid order Opiliones with over 4,000 described species worldwide. The majority of the species are highly dependent on humid environments and usually correlated with tropical and temperate forest habit ...

. In the suborder Cyphophthalmi, the ozopores are located on special ozophores, specialized elevated cones. Many different compounds have been found in various studied harvestman secretions. The chemical composition of the secretions seems to be useful in

taxonomic Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...

recognition. In the Laniatores, Gonyleptoidea produce alkylated

benzoquinone Benzoquinone (C6H4O2) is a quinone with a single benzene ring. There are 2 (out of 3 hypothetical) benzoquinones: * 1,4-Benzoquinone, most commonly, right image (also ''para''-benzoquinone, ''p''-benzoquinone, ''para''-quinone, or just quinone) * 1 ...

s and

phenol Phenol (also called carbolic acid) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile. The molecule consists of a phenyl group () bonded to a hydroxy group (). Mildly acidic, it req ...

s, and

Travunioidea Travunioidea is a superfamily of armoured harvestmen in the order Opiliones. There are 4 families and more than 70 described species in Travunioidea. Families These four families belong to the superfamily Travunioidea: * Cryptomastridae Derkarab ...

produce mainly

terpenoid The terpenoids, also known as isoprenoids, are a class of naturally occurring organic chemicals derived from the 5-carbon compound isoprene and its derivatives called terpenes, diterpenes, etc. While sometimes used interchangeably with "terpenes" ...

s. In the Eupnoi, the

Sclerosomatidae The Sclerosomatidae are a family of harvestmen with about 1,300 known species. Name The name is combined from Ancient Greek ''skleros'' "hard" and ''soma'' "body". (2007): Sclerosomatidae. Simon, 1879. In: Pinto-da-Rocha ''et al.'' 2007: 127ff ...

secrete short-chain acyclic

ketone In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double bo ...

s and

alcohol Alcohol most commonly refers to: * Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom * Alcohol (drug), an intoxicant found in alcoholic drinks Alcohol may also refer to: Chemicals * Ethanol, one of sev ...

s, and the

Phalangiidae The Phalangiidae are a family of harvestmen with about 380 known species. The best known is ''Phalangium opilio''. ''Dicranopalpus ramosus'' is an invasive species in Europe. It is not to be confused with the harvestman family Phalangodidae, wh ...

naphthoquinone Naphthoquinones constitute a class of organic compounds structurally related to naphthalene. Two isomers are common for the parent naphthoquinones: * 1,2-Naphthoquinone * 1,4-Naphthoquinone Natural products * Alkannin * Hexahydroxy-1,4-napht ...

Millipedes

In millipedes, ozopores are repeated serially on body segments, and usually situated laterally. Exceptions are members of the order

Glomerida Glomerida is an order of pill-millipedes found primarily in the Northern Hemisphere. They superficially resemble pill-bugs or woodlice, and can enroll into a protective ball. They have twelve body segments, 17 to 19 pairs of legs, and males hav ...

, which have ozopores located dorsally. Some members of the order

Julida Julida is an order (biology), order of millipedes. Members are mostly small and cylindrical, typically ranging from in length. Eyes may be present or absent, and in mature males of many species, the first pair of legs is modified into hook-like ...

have especially prominent ozadenes. File:Nemasomatidae (Julida) 2012-10-16-15.jpg, A

julida Julida is an order (biology), order of millipedes. Members are mostly small and cylindrical, typically ranging from in length. Eyes may be present or absent, and in mature males of many species, the first pair of legs is modified into hook-like ...

n millipede with prominent ozadenes File:Abacion magnum defensive glands crop2.png, Ozadenes (G) on the inside of a millipede segment

Footnotes

References

* (eds.) (2007): Harvestmen - The Biology of Opiliones. ''Harvard University Press'' {{ISBN, 0-674-02343-9 Arthropod anatomy Arachnid anatomy Harvestmen Exocrine system Myriapod anatomy