Sphaerotheriida
Encyclopedia
Sphaerotheriida is an order
of millipede
s in the subclass Pentazonia, sometimes known as giant pill millipedes. They inhabit the Southern Hemisphere. Like the Northern Hemisphere pill millipedes of the order Glomerida, these millipedes can roll into a ball when disturbed. When they are rolled-up, most sphaerotheriids reach a maximum size of a cherry or golf ball, but some species from Madagascar can even reach the size of a baseball (an example of island gigantism
). When rolled-up, predators are unable to unravel giant pill millipedes since the margins of their second and last dorsal plates fit perfectly into one another, creating a sealed ball. A few giant pill millipede species are able to produce sound, the only millipede taxa known to do this. This order of millipedes is also unique in that some African species are used for medicinal purposes.
; superficially all species and genera
look the same. Dorsally
, their head is followed by twelve body tergites (collum, thoracic shield, and ten normal tergites) and the anal shield. Ventrally, females possess twenty-one leg pairs (forty-two legs in total), while males carry two additional modified leg pairs, the anterior and posterior telopods under their anal shield. The telopods resemble chelae and/or clamp-like structures, which are probably used in holding the female during mating. In the position of the male telopods, the females instead have a sclerotized subanal plate, which in some species such as those belonging to the family Arthrosphaeridae, is enlarged and is used to produce vibrations (stridulation
). Furthermore unlike other large-bodied millipede orders, Sphaerotheriida do not have glands that excrete poisonous or ill-smelling substances. Therefore, they depend entirely on their rolling-up behavior for protection.
Sphaerotheriida somewhat resemble the North American and Eurasian pill millipedes of the order Glomerida, but are generally larger in size (20–80 mm or 0.78740157480315–3.1 body length): only the smallest Sphaerotheriida species are as small as the largest members of the order Glomerida. The orders differ in the number of tergites (10 or 11 in Glomerida, 12 in Sphaerotheriida) and legs (17 or 19 in Glomerida, 21 or 23 in Sphaerotheriida), and show great differences in their head morphology and genital openings, among other characters. Both orders have the ability to roll into a perfect ball, protecting the head, antennae, and the vulnerable underside. However, this rolled-up position (volvation) is achieved differently. In Glomerida, the enlarged second body ring (thoracic shield) has a more or less visible gap within which fit the tips of tergites 3–11, whereas in Sphaerotheriida the tips of tergites 3–12 fit perfectly into a groove on the thoracic shield. Juvenile sphaerotheriids show the same gap as the Glomerida. Many giant pill millipede species have special ledges ('locking carinae') on the underside of the tergite tips and the anal shield which can be moved above a brim on the thoracic shield. These millipedes remain passively locked-up since they need not continued muscle contraction to remain in the rolled-up position.
On Madagascar, some giant pill millipede species exhibit island gigantism
, reaching a size comparable to a tennis ball, baseball or even a small orange when rolled up. Recently, a very small form was also described from Madagascar: full-grown individuals of the species Microsphaerotherium ivohibiensis being just the size of a pea.
was the large southern continent that formed after the breakup of the supercontinent Pangaea
. It included the modern-day landmasses of South America, New Zealand, Australia, India, and Madagascar. It is believed that the Sphaerotheriida originated in Gondwana and then diverged into its various forms. Currently, 322 species in 23 genera are known, with numerous new species having been discovered recently. The sphaerotheriids are divided into four families whose distributions do not overlap: Procyliosomatidae, Zephronidae, Sphaerotheriidae
and Arthrosphaeridae. The most basal
family, Procyliosomatidae, lives in Australia and New Zealand. The Zephronidae (synonym Sphaeropoeidae) occurs in southeast Asia from the Himalayas and China south and east to Sulawesi and inhabits some Philippines islands. The family Sphaerotheriidae only occurs in southern Africa with isolated populations in Zimbabwe and Malawi (probably introduced). The Arthrosphaeridae are distributed in southern India and Madagascar.
A few giant pill millipede species have been dispersed by humans. Examples include the Sri Lankan Arthrosphaeridae species A. brandtii which has established a population in the Usambara hills, Tanzania, Africa, as well as some South African Sphaerotherium species which have isolated populations in Malawi. Another likely candidate is Sechelliosoma forcipatum, a small species of the southeast Asian family Zephronidae, currently only known from a single island in the Seychelles
.
s, feeding on dead organic matter such as leaves and wood on the forest floor. Giant pill millipedes, like earthworms, play an important role in decomposition
, releasing nutrient
s that are locked up in decaying organic matter
back into the soil. This process is essential for plant nutrition. It is possible that giant pill millipedes use special bacteria
in their gut, similar to the way termites do, to get energy out of non-easily digestible material such as lignin
.
Like most millipedes, sphaerotheriids mainly inhabit the leaf litter of humid forests. Some species, however, show an arboreal (tree-living) lifestyle, and for these organisms the rolling-up reflex has been suppressed.
which almost exclusively feeds on giant pill millipedes along with meerkat
s (Suricata suricata) which have been reported (at least in captivity) to throw rolled-up sphaerotheriids against rocks in order to break them. Besides their rolling-up behavior, it has been suggested that camouflage
may be another defense mechanism that giant pill millipedes use specifically to protect them from animals that hunt using vision, such as birds. Sphaerotheriids also need to cope with internal parasites
, with several species of nematodes living in them exclusively.
foods, their susceptibility to parasites, their dependence on special climatic conditions (<24°C/75°F at day, <18°C/65°F at night), and weakness caused during transport. Since no captive breeding programs have been initiated, all animals found in stores are caught in the wild.
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
of millipede
Millipede
Millipedes are arthropods that have two pairs of legs per segment . Each segment that has two pairs of legs is a result of two single segments fused together as one...
s in the subclass Pentazonia, sometimes known as giant pill millipedes. They inhabit the Southern Hemisphere. Like the Northern Hemisphere pill millipedes of the order Glomerida, these millipedes can roll into a ball when disturbed. When they are rolled-up, most sphaerotheriids reach a maximum size of a cherry or golf ball, but some species from Madagascar can even reach the size of a baseball (an example of island gigantism
Island gigantism
Island gigantism or insular giantism is a biological phenomenon in which the size of animals isolated on an island increases dramatically in comparison to their mainland relatives....
). When rolled-up, predators are unable to unravel giant pill millipedes since the margins of their second and last dorsal plates fit perfectly into one another, creating a sealed ball. A few giant pill millipede species are able to produce sound, the only millipede taxa known to do this. This order of millipedes is also unique in that some African species are used for medicinal purposes.
Morphology
Sphaerotheriida are characterized by a relatively conservative body morphologyMorphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
; superficially all species and genera
Genera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...
look the same. Dorsally
Dorsum (biology)
In anatomy, the dorsum is the upper side of animals that typically run, fly, or swim in a horizontal position, and the back side of animals that walk upright. In vertebrates the dorsum contains the backbone. The term dorsal refers to anatomical structures that are either situated toward or grow...
, their head is followed by twelve body tergites (collum, thoracic shield, and ten normal tergites) and the anal shield. Ventrally, females possess twenty-one leg pairs (forty-two legs in total), while males carry two additional modified leg pairs, the anterior and posterior telopods under their anal shield. The telopods resemble chelae and/or clamp-like structures, which are probably used in holding the female during mating. In the position of the male telopods, the females instead have a sclerotized subanal plate, which in some species such as those belonging to the family Arthrosphaeridae, is enlarged and is used to produce vibrations (stridulation
Stridulation
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 fishes, snakes and spiders...
). Furthermore unlike other large-bodied millipede orders, Sphaerotheriida do not have glands that excrete poisonous or ill-smelling substances. Therefore, they depend entirely on their rolling-up behavior for protection.
Sphaerotheriida somewhat resemble the North American and Eurasian pill millipedes of the order Glomerida, but are generally larger in size (20–80 mm or 0.78740157480315–3.1 body length): only the smallest Sphaerotheriida species are as small as the largest members of the order Glomerida. The orders differ in the number of tergites (10 or 11 in Glomerida, 12 in Sphaerotheriida) and legs (17 or 19 in Glomerida, 21 or 23 in Sphaerotheriida), and show great differences in their head morphology and genital openings, among other characters. Both orders have the ability to roll into a perfect ball, protecting the head, antennae, and the vulnerable underside. However, this rolled-up position (volvation) is achieved differently. In Glomerida, the enlarged second body ring (thoracic shield) has a more or less visible gap within which fit the tips of tergites 3–11, whereas in Sphaerotheriida the tips of tergites 3–12 fit perfectly into a groove on the thoracic shield. Juvenile sphaerotheriids show the same gap as the Glomerida. Many giant pill millipede species have special ledges ('locking carinae') on the underside of the tergite tips and the anal shield which can be moved above a brim on the thoracic shield. These millipedes remain passively locked-up since they need not continued muscle contraction to remain in the rolled-up position.
On Madagascar, some giant pill millipede species exhibit island gigantism
Island gigantism
Island gigantism or insular giantism is a biological phenomenon in which the size of animals isolated on an island increases dramatically in comparison to their mainland relatives....
, reaching a size comparable to a tennis ball, baseball or even a small orange when rolled up. Recently, a very small form was also described from Madagascar: full-grown individuals of the species Microsphaerotherium ivohibiensis being just the size of a pea.
Distribution
In general, sphaerotheriids are found only in the Southern Hemisphere in a Gondwanan distribution. GondwanaGondwana
In paleogeography, Gondwana , originally Gondwanaland, was the southernmost of two supercontinents that later became parts of the Pangaea supercontinent. It existed from approximately 510 to 180 million years ago . Gondwana is believed to have sutured between ca. 570 and 510 Mya,...
was the large southern continent that formed after the breakup of the supercontinent Pangaea
Pangaea
Pangaea, Pangæa, or Pangea is hypothesized as a supercontinent that existed during the Paleozoic and Mesozoic eras about 250 million years ago, before the component continents were separated into their current configuration....
. It included the modern-day landmasses of South America, New Zealand, Australia, India, and Madagascar. It is believed that the Sphaerotheriida originated in Gondwana and then diverged into its various forms. Currently, 322 species in 23 genera are known, with numerous new species having been discovered recently. The sphaerotheriids are divided into four families whose distributions do not overlap: Procyliosomatidae, Zephronidae, Sphaerotheriidae
Sphaerotheriidae
Sphaerotheriidae is a family of giant pill millipedes of the class Diplopoda. Millipedes of this family are distributed in South Africa. -Selected genera:...
and Arthrosphaeridae. The most basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
family, Procyliosomatidae, lives in Australia and New Zealand. The Zephronidae (synonym Sphaeropoeidae) occurs in southeast Asia from the Himalayas and China south and east to Sulawesi and inhabits some Philippines islands. The family Sphaerotheriidae only occurs in southern Africa with isolated populations in Zimbabwe and Malawi (probably introduced). The Arthrosphaeridae are distributed in southern India and Madagascar.
A few giant pill millipede species have been dispersed by humans. Examples include the Sri Lankan Arthrosphaeridae species A. brandtii which has established a population in the Usambara hills, Tanzania, Africa, as well as some South African Sphaerotherium species which have isolated populations in Malawi. Another likely candidate is Sechelliosoma forcipatum, a small species of the southeast Asian family Zephronidae, currently only known from a single island in the Seychelles
Seychelles
Seychelles , officially the Republic of Seychelles , is an island country spanning an archipelago of 115 islands in the Indian Ocean, some east of mainland Africa, northeast of the island of Madagascar....
.
Ecology
Little is known about the ecology, development and life history of Sphaerotheriids, but all species are most likely detritivoreDetritivore
Detritivores, also known as detritophages or detritus feeders or detritus eaters or saprophages, are heterotrophs that obtain nutrients by consuming detritus . By doing so, they contribute to decomposition and the nutrient cycles...
s, feeding on dead organic matter such as leaves and wood on the forest floor. Giant pill millipedes, like earthworms, play an important role in decomposition
Decomposition
Decomposition is the process by which organic material is broken down into simpler forms of matter. The process is essential for recycling the finite matter that occupies physical space in the biome. Bodies of living organisms begin to decompose shortly after death...
, releasing nutrient
Nutrient
A nutrient is a chemical that an organism needs to live and grow or a substance used in an organism's metabolism which must be taken in from its environment. They are used to build and repair tissues, regulate body processes and are converted to and used as energy...
s that are locked up in decaying organic matter
Organic matter
Organic matter is matter that has come from a once-living organism; is capable of decay, or the product of decay; or is composed of organic compounds...
back into the soil. This process is essential for plant nutrition. It is possible that giant pill millipedes use special bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
in their gut, similar to the way termites do, to get energy out of non-easily digestible material such as lignin
Lignin
Lignin or lignen is a complex chemical compound most commonly derived from wood, and an integral part of the secondary cell walls of plants and some algae. The term was introduced in 1819 by de Candolle and is derived from the Latin word lignum, meaning wood...
.
Like most millipedes, sphaerotheriids mainly inhabit the leaf litter of humid forests. Some species, however, show an arboreal (tree-living) lifestyle, and for these organisms the rolling-up reflex has been suppressed.
Defense against predation
Giant pill millipedes are preyed upon by a wide variety of organisms, and their rolling-up ability and tough skeletal armor offer protection against some predators. A few animals specialize on feeding on giant pill millipedes and have evolved special structures or behaviors to overcome their defensive mechanism. Examples include the South African snail family ChlamydephoridaeChlamydephoridae
Chlamydephoridae is a family of air-breathing land slugs, terrestrial pulmonate gastropod mollusks in the clade Eupulmonata .These snails are presumed to be true carnivores...
which almost exclusively feeds on giant pill millipedes along with meerkat
Meerkat
The meerkat or suricate, Suricata suricatta, is a small mammal belonging to the mongoose family. Meerkats live in all parts of the Kalahari Desert in Botswana, in much of the Namib Desert in Namibia and southwestern Angola, and in South Africa. A group of meerkats is called a "mob", "gang" or "clan"...
s (Suricata suricata) which have been reported (at least in captivity) to throw rolled-up sphaerotheriids against rocks in order to break them. Besides their rolling-up behavior, it has been suggested that camouflage
Camouflage
Camouflage is a method of concealment that allows an otherwise visible animal, military vehicle, or other object to remain unnoticed, by blending with its environment. Examples include a leopard's spotted coat, the battledress of a modern soldier and a leaf-mimic butterfly...
may be another defense mechanism that giant pill millipedes use specifically to protect them from animals that hunt using vision, such as birds. Sphaerotheriids also need to cope with internal parasites
Parasitism
Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred to organisms with lifestages that needed more than one host . These are now called macroparasites...
, with several species of nematodes living in them exclusively.
Pets
Sphaerotheriids are commonly found in the pet trade and are kept by terrarium enthusiasts in Japan, Europe, and the United States. The species usually either come from Madagascar or Malaysia. The survival rate for giant pill millipedes in captivity is quite low; they rarely live longer than one month. The reasons for their low survival rate in captivity is little understood. Some explanations include their reliance on low calorieCalorie
The calorie is a pre-SI metric unit of energy. It was first defined by Nicolas Clément in 1824 as a unit of heat, entering French and English dictionaries between 1841 and 1867. In most fields its use is archaic, having been replaced by the SI unit of energy, the joule...
foods, their susceptibility to parasites, their dependence on special climatic conditions (<24°C/75°F at day, <18°C/65°F at night), and weakness caused during transport. Since no captive breeding programs have been initiated, all animals found in stores are caught in the wild.
Taxonomy
- Family: Arthrosphaeridae
- Arthrosphaera Pocock, 1895 – 40 species, India, Sri Lanka
- Zoosphaerium Pocock, 1895 – 55 species, Madagascar
- SphaeromimusSphaeromimusSphaeromimus, or the chirping giant pill millipedes, is a genus of giant pill millipedes endemic to southeastern Madagascar...
de Saussure & Zehntner, 1902 – 3 species, southeast Madagascar - Microsphaerotherium Wesener & van den Spiegel, 2007 – 2 species, Madagascar
- Family: Procyliosomatidae
- ProcyliosomaProcyliosomaProcyliosoma is a genus of pill millipede of the family Sphaerotheriidae, found in Australia and New Zealand.-Species:* Procyliosoma andersoni – New South Wales* Procyliosoma aurivillii Silvestri, 1917 – Queensland...
Silvestri, 1917 – 11 species, Eastern Australia, Tasmania, New Zealand
- Family: Zephronidae
- Bothrobelum Verhoeff, 1924 – monotypic, Borneo
- Cryxus Leach, 1814 – monotypic, Asia
- Indosphaera Attems, 1935 – 2 species N. India, Myanmar
- Kophosphaera Attems, 1935 – 5 species, N. India, Nepal
- Leptotelopus Silvestri, 1897 – monotypic, Myanmar
- Prionobelum Verhoeff, 1924 – 8 species, Vietnam, SW China
- Sphaerobelum Verhoeff, 1924 – 4 species, Vietnam
- Zephronia Gray, 1832 – 37 species N. India, Myanmar, Malayan Peninsula, Java, Sumatra, Borneo
- Sphaeropoeus Brandt, 1833 – 22 species, N. India, Myanmar, Malayan Peninsula, Java, Sumatra, Borneo
- Tigridosphaera Jeekel, 2000 – 4 species, Malayan Peninsula
- Castanotherium Pocock, 1895 – 50 species, Indonesian Islands, Philippines
- Castanotheroides Chamberlin, 1921 – 3 species, Philippines
- Sechelliosoma Mauriès, 1980 – monotypic, Seychelles
- Rajasphaera Attems, 1935 – monotypic, Borneo
- Family: SphaerotheriidaeSphaerotheriidaeSphaerotheriidae is a family of giant pill millipedes of the class Diplopoda. Millipedes of this family are distributed in South Africa. -Selected genera:...
- Sphaerotherium Brandt, 1833 – 54 species, South Africa, Zimbabwe
- Kylindotherium Attems, 1926 – monotypic, South Africa
- Incertae sedisIncertae sedis, is a term used to define a taxonomic group where its broader relationships are unknown or undefined. Uncertainty at specific taxonomic levels is attributed by , , and similar terms.-Examples:*The fossil plant Paradinandra suecica could not be assigned to any...
- Epicyliosoma Silvestri, 1917 – 15 species, Australia
- Cynotelopus Jeekel, 1986 – monotypic, southwest Australia