Eggs ingested by a mammal travel down the alimentary tract and hatch in the small intestine. Within only 1 or 2 hours, the motile, primary larva penetrates the gut wall and migrates to the liver and the lungs of the mammal, eventually encysting and becoming encapsulated in tissues, including the viscera, mesenteries, and walls of the thoracic and abdominal body cavities. At about the seventh day, the primary larva become inactive, then undergo their first molt. Following molts, larvae grow larger in size. Mouth hooks are visible during the third nymphal stage and distint segmentation is visible after the 4th nymphal stage. Sexual differentiation occurs at the fifth nymphal stage. The snake ingests an intermediate mammal host containing seventh (VII) instar infective nymphs that excyst and penetrate the gut wall, migrating through the viscera and directly to the lungs. Within the lung cavities of the definitive host, infective seventh instar nymphs continue to molt and finally mature into male instar (X) and female instar (XI) adults to reproduce and complete the life cycle. Adults with mature eggs are expelled from the trachea and eliminated from the definitive host by oral expulsion. The adults may also be swallowed, resulting in shed eggs in the feces in which another intermediate mammal host will ingest to begin the life cycle again. (Brookins, et al., 2009; Buckle, et al., 1997; Esslinger, 1962a; Esslinger, 1962b; Layne, 1967; Self and Riley, 1979)
Reproduction occurs in the lungs of the definitive host and adult males and females reach sexual maturity approximately 16 days after infection of the VII larval instar. Copulation between adult males and females occurs approximately 75-86 days post-infection of the definive hosts. Females are able to store sperm in the spermathecae for several years. Females have enormous fecundicity. Egg production is continuous over 6-10 years. Egg production, however, does not begin until 230-250 days post-infection of the definitive host. There is a higher prevalence of infection during the warmer months of the year when hosts are more mobile in a warm environment. (Buckle, et al., 1997; Layne, 1967)
females do not exhibit any type of specific parental investment.
As an obligate endoparasite with a heteroxenous life cycle, Porocephlus crotali has both sessile and mobile stages. Nymphs are mobile during migration within intermediate host tissues and become sessile when encapsulated in the viscera. In the definitive host, nymphs are mobile during migration to the respiratory tract and also mobile in the snake's lungs. (Riley and Henderson, 1999)
There are no known predators of.
has no known benefits to humans.
is not an endangered species.
Michael Hoang (author), University of Michigan-Ann Arbor, Heidi Liere (editor), University of Michigan-Ann Arbor, John Marino (editor), University of Michigan-Ann Arbor, Barry OConnor (editor), University of Michigan-Ann Arbor, Renee Mulcrone (editor), Special Projects.
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.
an animal that mainly eats meat
an animal which directly causes disease in humans. For example, diseases caused by infection of filarial nematodes (elephantiasis and river blindness).
Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.
uses smells or other chemicals to communicate
used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.
having a worldwide distribution. Found on all continents (except maybe Antarctica) and in all biogeographic provinces; or in all the major oceans (Atlantic, Indian, and Pacific.
a substantial delay (longer than the minimum time required for sperm to travel to the egg) takes place between copulation and fertilization, used to describe female sperm storage.
in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.
a period of time when growth or development is suspended in insects and other invertebrates, it can usually only be ended the appropriate environmental stimulus.
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
union of egg and spermatozoan
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
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
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 one mate at a time.
having the capacity to move from one place to another.
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
an organism that obtains nutrients from other organisms in a harmful way that doesn't cause immediate death
a form of body symmetry in which the parts of an animal are arranged concentrically around a central oral/aboral axis and more than one imaginary plane through this axis results in halves that are mirror-images of each other. Examples are cnidarians (Phylum Cnidaria, jellyfish, anemones, and corals).
an animal that mainly eats blood
scrub forests develop in areas that experience dry seasons.
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
mature spermatozoa are stored by females following copulation. Male sperm storage also occurs, as sperm are retained in the male epididymes (in mammals) for a period that can, in some cases, extend over several weeks or more, but here we use the term to refer only to sperm storage by females.
a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
Living on the ground.
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
breeding takes place throughout the year
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Penn, Jr., G. 1942. The life history of Porocephalus crotali, a parasite of rhe Louisiana muskrat. The Journal of Parasitology, 28 (4): 277-283.
Riley, J. 1981. An experimental investigation of the development of Porocephalus crotali (Pentastomida: Porocephalida) in the western diamondback rattlesnack (Crotalus atrox). International Journal for Parasitology, 11 (2): 127-131.
Riley, J., R. Henderson. 1999. Pentastomids and the tetrapod lung. Parasitology, Volume 119: 89-105.
Self, J., J. Riley. 1979. On the systematics of the pentastomid genus Porocephalus (Humboldt, 1811) with descriptions of two new species. Systematic Parasitology, 1 (1): 25-42.
Tappe, D., D. Buttner. 2009. Diagnosis of human visceral pentastomiasis. Public Library of Science: Neglected Tropical Diseases, 3 (2): 1-7.