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Taenia taeniaeformis

By Manika Girdhar

Geographic Range

Taenia taeniaeformis is found worldwide where suitable hosts are present. It is not specific to any particular region. (Andreevich, 1963; Barnes, 1963; Meglitsch, 1967; Smyth, 1969; Yamaguti, 1953)

Habitat

Taenia taeniaeformis infects mainly rodents and cats so it is mainly a terrestrial organism. In unusual circumstances, it has been found in humans, but that instance is extremely rare. It infects cats mainly by way of mice. The mouse will be infected (secondary intermediate host) and when it is eaten by the cat, the worm will develop to its adult stage in the intestine of the feline. (Andreevich, 1963; Barnes, 1963; Meglitsch, 1967; Smyth, 1969; Yamaguti, 1953)

Physical Description

The adult Taenia taeniaeformis can be subdivided into three body sections. The anterior region in called the scolex, which is used to adhere to the intestine of the host species. In T. taeniaeformis, the scolex is made up of four large suckers arranged around the sides. Behind the scolex is the neck region, and finally the third region is the strobilus. The strobilus is made of many linearly arranged sections which make up the greater part of the worm. Each section contains a proglottid (the reproductive area of the worm). The neck region is fairly small, almost nonexistent, and it produces the proglottids by way of transverse constrictions. The youngest proglottids are therefore at the anterior region and they increase by size and maturity as they reach the posterior of the strobila. The tapeworms' nervous system and protonephridial system run through the segments. A large anterior nerve mass is located in the scolex and two lateral longitudinal cords extend through to the strobilus.

The tapeworm cuticle plays a very vital role in this species. It is important in the absorption of food since the worm lacks its own digestive system. It can reach anywhere from 15 cm to 60 cm and has one proglottid per segment with both males and female reproductive systems opening laterally. (Andreevich, 1963; Barnes, 1963; Meglitsch, 1967; Smyth, 1969; Yamaguti, 1953)

  • Range length
    15 to 60 cm
    5.91 to 23.62 in

Development

Taenia taeniaeformis infects intermediate hosts, including arthropods and vertebrates. The oncosphere, which hatches from an egg, makes up the basic larval stages. First, a rodent, most likely a rat, ingests the egg. The embryo emerges with hooks and uses the hooks to dig into the rat's tissues. They enter the gut and arrive in the liver via the blood. They do not migrate in the liver, but immediately begin developing into strobilocerci, which are housed in cyst-like tissue. From this, the strobilus and bladder are digested, and the scolex attaches to the small intestinal mucosa and matures in the host to become the adult tapeworm. (Andreevich, 1963; Barnes, 1963; Meglitsch, 1967; Smyth, 1969; Yamaguti, 1953)

Reproduction

Each proglottid goes through a complete reproductive process and the reproductive system within each section takes up a majority of the space. The tapeworm is hermaphroditic, with each proglottid containing both a male and female systems. Sometimes fertilization between proglottids or even in the same proglottid occurs, but it is very rare. Usually reproduction involves two worms.

The male system consists of numerous testes sporadically placed throughout or lying in lateral fields. Sperm ductules all unite within the proglottid to form the sperm duct, which coils and enters the copulatory complex. The male system ends in an intromittent organ, the cirrus contained in a cirrus sac. To form a propulsion vesicle, the muscles of the sperm duct or the ejaculatory duct dilate.

In the female system, a single, dorsoventrally positioned ovary lies in each proglottid. Yolk glands form a compact organ inside Taenia taeniaeformis as well. A yolk-duct system turns into a single duct, and eventually connects with the oviduct after it emerges from the ovary. With strong peristaltic contractions, an ovicapt pulls ova into the oviduct. Branching off from the oviduct, near the ovicapt, a vagina branches off and runs to the genital atrium, which contains a dilated seminal receptacle (where sperm are stored during mating). Further than the vagina, the duct continues to form a uterus, which is small at immaturity, but eventually grows to coil and branch, filled with ova. The ova leave either when the proglottid is shed, or though a small uterine pore.

During copulation, the cirrus of the male proglottid is inserted into a vaginal opening of a nearby worm. The sperm are first stored in the seminal receptacle and then released for fertilization. Eventually, terminal proglottids break away from the strobilus. The eggs are then freed when the proglottid ruptures as it is released, either in the host's intestine, or in the feces of the host. (Andreevich, 1963; Barnes, 1963; Meglitsch, 1967; Smyth, 1969; Yamaguti, 1953)

  • Parental Investment
  • no parental involvement

Behavior

Taenia taeniaeformis infects intermediate hosts, including arthropods and vertebrates. The oncosphere, which hatches from an egg, makes up the basic larval stages. First, a rodent, most likely a rat, ingests the egg. The embryo emerges with hooks and uses the hooks to dig into the rat's tissues. They enter the gut and arrive in the liver via the blood. They do not migrate in the liver, but immediately begin developing into strobilocerci, which are housed in cyst-like tissue. From this, the strobilus and bladder are digested, and the scolex attaches to the small intestinal mucosa and matures in the host to become the adult tapeworm. (Andreevich, 1963; Barnes, 1963; Meglitsch, 1967; Smyth, 1969; Yamaguti, 1953)

Communication and Perception

Cestodes in general have sensory organs in the scolex, which are attached to longitudinal nerves extending down the body. The nerves are attached to organs and the cestodes can detect tactile stimulation. (Brusca and Brusca, 2003)

Food Habits

Taenia taeniaeformis are internal parasites that absorb food through their body surface because they lack a digestive system of their own. Since they are located in the intestines of their host, they take advantage of the already digested food and directly absorb the nutrients. Although not often, the scolex (which bears the suckers) is sometimes able to absorb materials not available to the other body segments, but absorption mainly occurs throughout the segments. (Andreevich, 1963; Barnes, 1963; Meglitsch, 1967; Smyth, 1969; Yamaguti, 1953)

  • Animal Foods
  • body fluids

Predation

These animals are probably not preyed on directly but are ingested. Egg and larval mortality are high since the parasite often do not reach appropriate hosts.

Ecosystem Roles

Taenia taeniaeformis infects mainly rodents and cats. In unusual circumstances, it has been found in humans, but that instance is extremely rare.

Species Used as Host

Economic Importance for Humans: Negative

This tapeworm infests rats and cats, it has no direct importance toward human welfare. If humans are in direct contact with pet/domestic cats, they can possibly become a host for this tapeworm, although this is rare.

Contributors

Renee Sherman Mulcrone (editor).

Manika Girdhar (author), University of Michigan-Ann Arbor, Teresa Friedrich (editor), University of Michigan-Ann Arbor.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

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Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

agricultural

living in landscapes dominated by human agriculture.

bilateral symmetry

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.

carnivore

an animal that mainly eats meat

causes disease in humans

an animal which directly causes disease in humans. For example, diseases caused by infection of filarial nematodes (elephantiasis and river blindness).

causes or carries domestic animal disease

either directly causes, or indirectly transmits, a disease to a domestic animal

chaparral

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.

cosmopolitan

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.

desert or dunes

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.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

heterothermic

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.

internal fertilization

fertilization takes place within the female's body

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

parasite

an organism that obtains nutrients from other organisms in a harmful way that doesn't cause immediate death

rainforest

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.

scrub forest

scrub forests develop in areas that experience dry seasons.

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

suburban

living in residential areas on the outskirts of large cities or towns.

tactile

uses touch to communicate

temperate

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).

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

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.

savanna

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.

temperate grassland

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.

urban

living in cities and large towns, landscapes dominated by human structures and activity.

References

Andreevich, A. 1963. Anoplocephalate Tapeworms of Domestic and Wild Animals. Moscow: The Academy of Sciences of the USSR.

Barnes, R. 1963. Invertebrate Zoology. Philadelphia: Saunders.

Brusca, R., G. Brusca. 2003. Invertebrates. Sunderland, Massachusetts: Sinauer Associates, Inc..

Mah, K., T. Nolan. 2004. "Taenia taeniaeformis Homepage" (On-line). Diagnosis of Veterinary Endoparasitic Infections. Accessed October 18, 2004 at http://cal.vet.upenn.edu/dxendopar/parasitepages/cestodes/taeniaformis.html.

Meglitsch, P. 1967. Invertebrate Zoology. New York: Oxford University Press.

Smyth, J. 1969. The Phisiology [PHYSIOLOGY] of Cestodes. San Francisco: W.H. Freeman.

Yamaguti, S. 1953. Systema Helminthum. Tokyo: The Author.

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