Amphilina foliacea

Geographic Range

Amphilina foliacea lives in anadromous sturgeons that migrate between freshwater and saltwater in temperate areas. This species affects ‘ancient’ fish such as acipenserids widely distributed in the northern hemisphere: Europe (Eastern and Northern) and Asia (Siberia). (Rohde, 1998; Woo and Leatherland, 2006)


Amphilina foliacea is parasitic on aquatic animals, mainly living in the body cavity of freshwater and marine fishes, and sometimes in turtles. This cestode species inhabits different environments through its various life stages. The eggs are released in water. Either a free swimming larva or the egg is consumed by the first intermediate host (a small crustacean). If the larva has not already been released, the cestode egg is broken open as the crustacean eats the egg. The larval cestode then penetrates the tissue of the crustacean and metamorphoses into a procercoid. Fish eat the crustacean and the procercoid transforms into a plerocercoid in the fish's body cavity. The last stage is when sturgeon feed on the second intermediate host (the fish) and the adult parasites grow and reproduce in the body cavity. Adult cestodes gradually move to body organs and intestines causing diseases. Usually, the liver is affected and fat content in the infected sturgeons decrease. (Rohde, 1998; Woo and Leatherland, 2006)

Physical Description

Amphilina foliacea is a large worm with a flattened leaf-like body, free of any proglottids and intestines. An individual larva or adult has ten hooks of several shapes at the posterior end. Juveniles and adults have a similar morphology. An adult is monozoic (having a single genetalium), dorso-ventrally flattened and leaf-like in outline. An adult A. foliacea has both male and female reproductive organs. The anterior end is pointed and has an invaginated tegument to form teeth. An individual juvenile has a funnel-shaped proboscis at the anterior end to move into the hosts' body cavity and to hold onto the tissues within the host to prevent being removed in the feces. The uterine pore (anterior), vaginal pore (postero-lateral) and the ejaculatory pore (posterior) are all placed away from each other. The posterior end has a rosette-like structure. (Davydov and Kuperman, 1993; John R. Baker, 1983; Rohde, 1998; Woo and Leatherland, 2006)

  • Range length
    28 to 65 mm
    1.10 to 2.56 in


The development of this species goes through many stages. The egg is released through the uterine pore and the larva is ciliated for better swimming to move closer to the intermediate host (crustacean) in which they develop into procercoid. The second intermediate host is a fish where the procercoid metamorphes into plerocercoid. There is a possibility that paratenic hosts involved (other fish eat infected fish). The definitive hosts may have been a terestrial. The terrestrial animal may have disappeared due to evolutionary changes and the intermediate host (fish) became the definitive host. The most probable reason is the larval stages began developing into adults in the fishes before even getting into the final hosts or they have evolved to sexually reproduce in the intermediate hosts. During this evolutionary process, turtles may have been the intermediate between land and aquatic animals. (Davydov and Kuperman, 1993; Khanna and Yadav, 2004; Rohde, 1998)


Amphilina foliacea is a hermaphrodite and has well-developed mechanisms that enable cross-fertilization and self-fertilization. (Davydov and Kuperman, 1993; Heinz Mehlhorn, 2008; John R. Baker, 1983; Khanna and Yadav, 2004; Rohde, 1998)

As soon as the plerocercoid reaches the definitive host it reproduces rapidly and lays millions of eggs but loses a lot of energy during fertilization. The eggs are smaller and in large quantities compared to other dioecious parasites. If the plerocercoid gets into the wrong host, it will still reproduce. (Davydov and Kuperman, 1993; Khanna and Yadav, 2004; Woo and Leatherland, 2006)

  • Breeding interval
  • Breeding season
  • Range number of offspring
    millions (high)
  • Range gestation period
    less than 2 (low) minutes
  • Parental Investment
  • no parental involvement


The lifespan of a parasite depends on the lifespan of the host. Because of the transmission stages and the dependence on intermediate hosts it is difficult to estimate the longevity of A. foliacea. The definitive host, in the genus Acipenser, lives almost 40 years uninfected but the parasites likely live fewer years due to the constant damaging of the fish's liver and other body organs. The parasite's presence also diminishes the fish's lifespan. And as the hosts age, the number of parasites likely increases. (Heinz Mehlhorn, 2008; Khanna and Yadav, 2004; Rohde, 1998)

  • Range lifespan
    Status: wild
    6 to 40 years
  • Typical lifespan
    Status: captivity
    6 to 40 years


As a parasite A. foliacea behaves mainly to find and penetrate its host. Once inside, this cestode survives by absorbing nutrients through the tegument. It reproduces in the body cavity and lays eggs that are released through the coelemic pores of the host. These pores connect the body cavity to the outside. The cestode behaves differently as a larva and adult. The parasite also affects its host's behavior. A larva makes the intermediate host more vulnerable to predation to ensure access to the next host. (Davydov and Kuperman, 1993; Rohde, 1998; Woo and Leatherland, 2006)

Communication and Perception

The parasite's larval stage has many sensory receptors to perceive the environment. Glia cells and the ring commissure help signals to be passed in the worms to penetrate fish muscles and tissues. The nervous system also allows the larva to secrete enzymes necessary to inject into the host (the operculum on the egg is burst open to release such enzymes). The vibrations and chemical secretions from animals makes the larva move randomly and faster in the direction of the animal. Mostly in the cestode adults, the tegument is used to absorb the nutrients. (Biserova, et al., 2000; Davydov and Kuperman, 1993)

Food Habits

This species takes in nutrients from the definitive host (fish) through the syncitium tegument. (Davydov and Kuperman, 1993)

  • Animal Foods
  • body fluids


There are no anti-predation adaptations to this species but they do make their intermediate hosts act certain ways to be attacked (a crustacean may move faster in circles or even change its course by bringing it closer to the water surface so the fish can eat it). The plerocercoid loses its cilia and uses its proboscis to penetrate itself into the host body organs and body cavity. (Davydov and Kuperman, 1993; Rohde, 1998; Woo and Leatherland, 2006)

Ecosystem Roles

Amphilina foliacea is a parasite to the marine fish Acipenser ruthenus and Acipenser stellatus. The cestode does not initially do any significant harm to the sturgeons, but gradually enters the body organs to gain more and more nutrients, resulting in the hosts becoming diseased. The diseases may be lethal to the sturgeons or contribute to the decline of the host fish's fitness. (Rohde, 1998; Woo and Leatherland, 2006)

Species Used as Host

Economic Importance for Humans: Positive

Cestodes in general can be used as indicators for water quality and for the use of helminth transmission in marine pollution studies. As pollution increases, the population for ectoparasites in water environments will increase more than endoparasites because the species are making changes in their transmission stages as the environment changes around them. The decline of cestodes likely indicates the decline in one of it's host species. (Hurd, et al., 2001; MacKenzie, et al., 1995; Mackenzie, 1999)

  • Positive Impacts
  • research and education

Economic Importance for Humans: Negative

Worms in the body cavity of the sturgeon penetrates the liver, gonads and muscles, leading to hyperanemia and hemorrhages followed by extensive inflammation. Capsules are formed around the parasites which continue to grow with time. The parasite has a negative effect on both its host and may have a negative effect on humans by causing allergic reactions, inflammation and larval migration in the body tissues and under the skin. Since the humans are the wrong host, the worms would die as they travel and calcify causing pain and bulges on the body. This may also lead to many diseases and slower blood circulation. (Heinz Mehlhorn, 2008; John R. Baker, 1983; Khanna and Yadav, 2004; Rohde, 1998)

Conservation Status


Sonam Mehta (author), Rutgers University, Nirali Patel (author), Rutgers University, David V. Howe (editor), Rutgers University, Renee Mulcrone (editor), Special Projects.


Arctic Ocean

the body of water between Europe, Asia, and North America which occurs mostly north of the Arctic circle.


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.

World Map


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

World Map

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.

brackish water

areas with salty water, usually in coastal marshes and estuaries.

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).


uses smells or other chemicals to communicate


the nearshore aquatic habitats near a coast, or shoreline.


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


mainly lives in water that is not salty.


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


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.

native range

the area in which the animal is naturally found, the region in which it is endemic.


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

World Map


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


condition of hermaphroditic animals (and plants) in which the male organs and their products appear before the female organs and their products


Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.


remains in the same area


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


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).


movements of a hard surface that are produced by animals as signals to others


Biserova, N., V. Dudicheva, N. Terenina, M. Reuter, D. Halton. 2000. The nervous system of Amphilina foliacea (Platyhelminthes, Amphilinidea). An immunocytochemical, ultrastructural and spectrofluorometrical study. Parasitology, 121: 441-453.

Davydov, V., B. Kuperman. 1993. The ultrastructure of the tegument and the peculiarities of the biology of Amphilina foliacea adult. Folia Parasitologica, 40: 13-22. Accessed February 28, 2011 at

Heinz Mehlhorn, 2008. Encyclopedia of parasitology. New York: Springer.

Hurd, H., E. Warr, A. Polwart. 2001. A parasite that increases host lifespan. The Royal Society, 268: 1749-1753. Accessed February 28, 2011 at

John R. Baker, 1983. Advances in Parasitology. United States of America: Academic Press.

Khanna, D., P. Yadav. 2004. Biology Of Helminthes. New Delhi: Discovery Publishing House. Accessed January 07, 2011 at

MacKenzie, K., H. Williams, B. Williams, A. McVicar, R. Siddall. 1995. Parasites as indicators of water quality and the potential use of helminth transmission in marine pollution studies. Advances in Parasitology, 35: 85-114.

Mackenzie, K. 1999. Parasites as pollution indicators in marine ecosystems: A proposed early warning system. Marine Pollution Bulletin, 38 (11): 955-959.

Rohde, K. 1998. "Amphilinidea" (On-line). The Tree of Life Web Project. Accessed January 07, 2011 at

Woo, P., J. Leatherland. 2006. Fish disease & disorders: protozoan & metazoan infections. London, UK: CAB International. Accessed January 08, 2011 at,+John+F.+Leatherland+&ots=ZAC3lRB0ZW&sig=YJ0gulF7uKXF3Is90FiB3okk0Rw#v=onepage&q=&f=false.