Animal Diversity Web

Ge­o­graphic Range

The range of Leu­cochlo­rid­ium para­doxum fol­lows that of its host, snails of the genus Suc­cinea that live in Eu­rope and North Amer­ica. (Dawes, 1946; Ren­nie, 1992)

• Biogeographic Regions
• nearctic
  • native
• palearctic
  • native

Habi­tat

The worm is both an en­dopar­a­site of Suc­cinea snails and of var­i­ous birds such as crows, jays, spar­rows and finches. It en­coun­ters these an­i­mals in tem­per­ate forests of North Amer­ica and Eu­rope. The egg is the only stage of de­vel­op­ment that ex­ists out­side of a host but it must re­main moist to sur­vive. (Dawes, 1946; Ren­nie, 1992)

• Habitat Regions
• terrestrial

• Terrestrial Biomes
• forest

• Other Habitat Features
• agricultural

Phys­i­cal De­scrip­tion

The worm has dif­fer­ent sizes and shapes through­out its de­vel­op­ment. The eggs are brown and oval shaped. After hatch­ing, the miracidia or first stage lar­vae are clear and elon­gate. After trans­for­ma­tion, the miracidia be­come sack-like ob­jects called sporo­cysts. The sporo­cysts cause the eye­stalks of their snail hosts to pul­sate yel­low, green, and red. Some sporo­cysts then give rise to cer­caria, or ju­ve­niles, which have tails and a more com­plex di­ges­tive tract. The cer­caria have a lined ex­cre­tory blad­der which ex­tends into their tails a bit and the tails also have fin­folds on the top and bot­tom as well as setae on the sides. The cer­caria also have two eye­spots. Cer­caria quickly be­come an en­cysted metac­er­caria from which emerge the adults. The adults are spined, long, dor­sally flat­tened, and have suck­ers for at­tach­ment within their de­fin­i­tive hosts. (Fried and Graczyk, 1997; Roberts and Janovy Jr., 2000)

• Other Physical Features
• ectothermic
• heterothermic
• bilateral symmetry

De­vel­op­ment

After a suc­cinid snail in­gests the worm's eggs, the sporo­cysts that arise from the miracidia have one of two des­tinies. Some sporo­cysts give rise to cer­caria and oth­ers asex­u­ally pro­duce more daugh­ter sporo­cysts. When a bird in­gests the snail, the re­main­ing sporo­cysts be­come cer­caria, which even­tu­ally de­velop into adults. The adults are mo­noe­cious, or her­maph­ro­ditic, al­though they can cross fer­til­ize when in close prox­im­ity. The re­sult­ing eggs are re­leased by the worms in the rec­tum and ex­creted by the bird host along with its feces. (Eras­mus, 1972; Fried and Graczyk, 1997; Roberts and Janovy Jr., 2000)

Re­pro­duc­tion

Leu­cochlo­rid­ium para­doxum re­pro­duces asex­u­ally. The adults are mo­noe­cious, or her­maph­ro­ditic, al­though they can cross fer­til­ize when in close prox­im­ity. The re­sult­ing eggs are re­leased by the worms in the rec­tum and ex­creted by the bird host along with its feces. (Eras­mus, 1972; Fried and Graczyk, 1997; Roberts and Janovy Jr., 2000)

• Key Reproductive Features
• simultaneous hermaphrodite
• sexual
• asexual
• fertilization
  • internal
• oviparous

There is no parental in­vest­ment be­yond the time eggs are re­leased.

• Parental Investment
• no parental involvement
• pre-fertilization
  • provisioning

Be­hav­ior

For Leu­cochlo­rid­ium para­doxum to con­tinue de­vel­op­ment, it must be con­sumed by a snail of the genus Suc­cinea. Once in­side a snail, the eggs hatch into miracidia that then be­come sporo­cysts. Sporo­cysts ac­cu­mu­late in the he­patopan­creas of the snail and in a brood­sac in the head-foot of the host. Many sporo­cysts move to the ten­ta­cles of the snail. (Brand, 1979; Dawes, 1946; Ren­nie, 1992; Roberts and Janovy Jr., 2000)

• Key Behaviors
• parasite
• motile
• sedentary

Com­mu­ni­ca­tion and Per­cep­tion

Bris­tles and small spines prob­a­bly act as tac­tile re­cep­tors, and these an­i­mals may have re­duced chemore­cep­tors. (Br­usca and Br­usca, 2003; Roberts and Janovy Jr., 2000)

• Communication Channels
• chemical

• Perception Channels
• tactile
• chemical

Food Habits

Leu­cochlo­rid­ium para­doxum is an en­dopar­a­site of the rec­tum of birds as an adult. There it feeds on pass­ing di­gested mat­ter. It shows lit­tle de­fin­i­tive host speci­ficity as it is known to par­a­sitize more than fif­teen bird species in­clud­ing crows, jays, spar­rows and finches. As a sporo­cyst, the worm ab­sorbs nu­tri­ents through its tegu­ment from its in­ter­me­di­ate hosts, Suc­cinea snails. (Dawes, 1946; Roberts and Janovy Jr., 2000)

• Primary Diet
• carnivore
  • eats body fluids

• Animal Foods
• body fluids

• Other Foods
• dung

Pre­da­tion

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

Ecosys­tem Roles

The worm is both an en­dopar­a­site of Suc­cinea snails and of var­i­ous birds such as crows, jays, spar­rows and finches. It en­coun­ters these an­i­mals in tem­per­ate forests of North Amer­ica and Eu­rope. The egg is the only stage of de­vel­op­ment that ex­ists out­side of a host but it must re­main moist to sur­vive.

• Ecosystem Impact
• parasite

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Leu­cochlo­rid­ium para­doxum pre­sents no known ben­e­fits to hu­mans.

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

The par­a­sitism of Leu­cochlo­rid­ium para­doxum on suc­cinid snails has no ef­fect on hu­mans. In their de­fin­i­tive bird hosts, they in­habit the rec­tum where they es­sen­tially feed on waste that is about to be ex­creted so their path­o­genic ef­fects on their hosts and ul­ti­mately on hu­mans are neg­li­gi­ble.

Con­ser­va­tion Sta­tus

• IUCN Red List

  Not Evaluated

Other Com­ments

Two vis­i­ble changes in the snail occur as a re­sult of the ac­cu­mu­la­tion of sporo­cysts. First, the snail's ten­ta­cles en­large and pulse in vivid col­ors. Sec­ondly, the in­stinc­tively pho­to­pho­bic snail be­comes pho­to­phylic and climbs to the tops of trees and grasses. This con­spic­u­ous sight looks like a cater­pil­lar to pass­ing birds. The birds swoop down and con­sume the snail and un­know­ingly in­oc­u­late them­selves with Leu­cochlo­rid­ium para­doxum. The worm con­tin­ues its de­vel­op­ment within the bird's gut and ul­ti­mately ends up in the rec­tum where its eggs are flushed out with waste. An­other snail con­sumes the ex­creted egg and the cycle con­tin­ues. How the worm is able to cause such a dras­tic change in Suc­cinea is still un­known. (Brand, 1979; Dawes, 1946; Ren­nie, 1992; Roberts and Janovy Jr., 2000)

Con­trib­u­tors

Renee Sher­man Mul­crone (ed­i­tor).

David DeLaCruz (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor, Teresa Friedrich (ed­i­tor), Uni­ver­sity of Michi­gan-Ann Arbor.

Ref­er­ences

Brand, T. 1979. Bio­chem­istry and Phys­i­ol­ogy of En­dopar­a­sites. Am­s­ter­dam: El­se­vier/North-Hol­land Bio­med­ical Press.

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

Dawes, B. 1946. The Trema­toda. Cam­bridge, UK: Uni­ver­sity Press.

Eras­mus, D. 1972. The Bi­ol­ogy of Trema­todes. New York: Crane, Rus­sack, & Com­pany.

Fried, B., T. Graczyk. 1997. Ad­vances in Trema­tode Bi­ol­ogy. Boca Raton, FL: CRC Press.

Ren­nie, J. 1992. Trends In Par­a­sitol­ogy: Liv­ing To­gether. Sci­en­tific Amer­i­can, Jan­u­ary: 123-33.

Roberts, L., J. Janovy Jr.. 2000. Foun­da­tions of Par­a­sitol­ogy 6th ed.. Boston: Mc­Graw-Hill.