Gromphadorhina portentosa is primarily found in the tropical lowland rainforests of Madagascar. They tend to live in the dry litter on the forest floor. (Copeland, 2003; Ryan, et al., 1993; Yoder and Grojean, 1997)
Like most insects, Gromphadorhina portentosa has a head, thorax, abdomen, and 6 legs. Unlike many cockroach species, they do not possess wings. Their exoskeleton is dark, from mahogany brown to black, and very thick, hard, and waxy. They have pads and hooks on their feet that allow them to climb smooth surfaces. Males possess a pair of large bumps or tubercles behind their head, these structures are much smaller in females. These horns are known as pronatal humps. Gromphadorhina portentosa is one of the largest species of the cockroaches in the world, adults are 5.1 to 10.2 cm long, with males growing larger than females. (Clark and Moore, 1995a; Copeland, 2003; Guthrie and Tindall, 1968; Milius, 2002; Miller, 1977)
Madagascar hissing cockroachs have an incomplete or partial metamorphosis. They hatch from eggs as nymphs, which are quite similar to adults in general structure, but lack reproductive organs. Nymphs molt their exoskeleton six times as they grow to adulthood, a process that usually takes 6-7 months. (Fraser and Nelson, 1984; Guthrie and Tindall, 1968)
Male Madagascar hissing cockroaches produces acoustic sounds or hissing during courtship interactions with females. Males typically produce two types of signals, a calling sound and a courtship sound. The calling sound is a long distance song that is used to attract females while the courtship sound is used more during close range interaction.
Adult male hissing cockroaches defend mating territories from other males, and attempt to monopolize mating with all the females in their territory. Males interact by hissing, and in bouts of pushing and shoving. Cockroach mating can occur year around, but only when the climate is warm. (Clark and Moore, 1994; Guthrie and Tindall, 1968; Matthews and Matthews, 1978; Roeder, 1963; Sreng, 2005)
Male hissing cockroaches are attracted and stimulated by the odor of the female. The males have specialized sense organs on their antennae for this. The amount of sex attractant secreted is higher in virgin females, although the output can be sporadic. It decreases with age. When the male is attracted to the female by this scent, he begins to hiss and touch her antennae. The pair then attaches to one another and turn rear to rear and remain in this position for 30 minutes. The females carry the ootheca, a long yellowish egg case, internally and they release the young nymphs after the eggs have hatched. Typically 15 - 40 cockroach nymphs will emerge. (Clark and Moore, 1994; Guthrie and Tindall, 1968; Matthews and Matthews, 1978; Roeder, 1963; Sreng, 2005)
Female Madagascar hissing cockroaches provision their eggs, then carry them after fertilization until they hatch. (Clark and Moore, 1994; Guthrie and Tindall, 1968; Matthews and Matthews, 1978; Roeder, 1963)
Madagascar hissing cockroaches can live up to five years. (Clark and Moore, 1995a)
Male Madagascar hissing cockroaches establish territories that are defended from other adult males. Aggressive hissing and posturing behavior is used to warn intruders away. The male that is larger and hisses more usually wins. The dominant males stand on their "toes," which is called stilting. Stilting is a way for males to "show off." The males use their pronatal humps when fighting other males to defend territories. Fighting between males does not appear to injure the males. Females and nymphs are more social and do not fight with one another or with males. The cockroaches are nocturnal and they avoid light. (Fraser and Nelson, 1984; Gordon, 1996; Yoder and Grojean, 1997)
Territory sizes are rather small. A male may sit on a rock for months and defend it from other males, only leaving to occasionally obtain food and water. Females do not defend a territory like this. (Guthrie and Tindall, 1968; Mulder, 2008)
The Madagascar hissing cockroach is unique in its ability to make a "hissing" sound. These cockroaches hiss through the breathing spiracles located on their abdomens. This hissing sound is used to communicate with its own species and others. Four hisses with different social purposes and amplitude patterns have been identified: a male combat hiss, two types of courting and mating hisses, and an alarm hiss (a loud snake-like hissing that startles predators). (Clark and Moore, 1995b; Clopton, 1995; Copeland, 2003; Fraser and Nelson, 1984; Guthrie and Tindall, 1968; Matthews and Matthews, 1978; Miller, 1977; Nelson and Fraser, 1980; Yoder and Grojean, 1997)
Madagascar hissing cockroaches are detritivores. Their most frequent food is decaying plant material, including fallen fruit, because it is so readily available. They also eat smaller insects and animal carcasses. (Clark and Moore, 1994; Guthrie and Tindall, 1968)
Hissing cockroaches probably have many types of predators, but there are few documented relationships. Arachnids, ants, tenrecs, and some ground-feeding birds are likely predators. As previously mentioned, an anti-predatory strategy is an alarm hiss - producing a loud snake-like noise that may startle potential predators. (Clark and Moore, 1994; Copeland, 2003; Guthrie and Tindall, 1968)
Gromphadorhina portentosa plays a role in the rainforests of Madagascar by recycling a large amount of decaying plant and animal matter.
The mite Androlaelaps schaeferi, formerly Gromphadorholaelaps schaeferi, is a common parasite of this cockroach. These mites form small clumps of four to six individuals at the base of the leg of their cockroach host. While it was originally thought that this mite was sanguinivorous (blood-sucking), recent studies showed that the mite simply "shares" in a cockroach's food items. (Clark and Moore, 1994; Guthrie and Tindall, 1968; Yoder and Barcelona, 1995; Yoder and Grojean, 1997)
This species is part of the nutrient cycling process in Malagasy forests. These forests are important as sources of timber, for water quality, and sources of other natural products.
Hissing cockroaches are also sold commercially in the pet trade. (Guthrie and Tindall, 1968)
There are no known adverse effects of Gromphadorina portentosa on humans.
Because the Madagascar hissing cockroach is only found in Madagascar, little conservation efforts have been done. This is due to political turmoil. Since the Malagasy people were forced out by the French colonizers in the 1960’s, the country has gone from dictatorship to dictatorship. It is difficult for field biologists to research the area due to the sparse network of passable roads. In the recent years, Liberation and international aid have made it easier for biologists to study Madagascar focusing on the hissing cockroach. The Madagascar hissing cockroaches huddle together in the forest. These pockets of natural forest are dying by degradation and fragmentation and because of this Madagascar has become a top priority for conservation biologists. Hundreds of millions of dollars have been contributed over the past three decades to help conservation efforts in Madagascar. (Bohannon, 2003; Fraser and Nelson, 1984)
Ashley Jessee (author), Radford University, Karen Francl (editor, instructor), Radford University.
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
uses sound to communicate
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
helps break down and decompose dead plants and/or animals
flesh of dead animals.
uses smells or other chemicals to communicate
an animal that mainly eats decomposed plants and/or animals
particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
union of egg and spermatozoan
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
fertilization takes place within the female's body
animals that live only on an island or set of islands.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
reproduction in which eggs develop within the maternal body without additional nourishment from the parent and hatch within the parent or immediately after laying.
the business of buying and selling animals for people to keep in their homes as pets.
chemicals released into air or water that are detected by and responded to by other animals of the same species
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
having more than one female as a mate at one time
rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
uses touch to communicate
Living on the ground.
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
uses sight to communicate
breeding takes place throughout the year
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