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Bipalium

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Bipalium
Model of Bipalium strubelli Graff, 1899
Scientific classification
Kingdom:
Animalia
Phylum:
Platyhelminthes
Class:
Rhabditophora
Order:
Tricladida
Suborder:
Continenticola
Family:
Geoplanidae
Subfamily:
Bipaliinae
Genus:
Bipalium

Synonyms
  • Sphyrocephalus Schmarda, 1859
  • Dunlopea Wright, 1860
  • Bipaliura Stimpson, 1861 (misspelling?)
  • Perocephalus von Graff, 1896 (in part)
  • Placocephalus von Graff, 1896 (in part)

Bipalium is a genus of large predatory land planarians. They are often loosely called "hammerhead worms" or "broadhead planarians" because of the distinctive shape of their head region. Land planarians are unique in that they possess a "creeping sole" on their ventral side.[2] Several species are considered as invasive to the United States[3] and to Europe.[4] Some studies have begun the investigation of the evolutionary ecology of these invasive planarians.[5]

Etymology

The name Bipalium comes from Latin bi-, two + pala, shovel or spade, because species in this genus resemble a pickaxe.[6]

Feeding habits

Bipalium species are predatory. Some species prey on earthworms, while others may also feed on mollusks.[7][8] It has been shown that these flatworms can track their prey.[9] When captured, earthworms will begin to react to the attack, but a flatworm uses the muscles in its body as well as sticky secretions to attach itself to the earthworm to prevent escape. Several studies have indicated that the planarians will cover, or cap the prostomium, peristomium and anterior end to stop the violent reaction by the earthworm.[10]

To feed on their prey, species of Bipalium often evert their pharynx from their mouth, located on the mid-ventral portion of the body, and secrete enzymes that begin the digestion of the prey. The liquefied tissues are sucked into the branching gut of the flatworm by ciliary action.[11]

Reproduction

Reproduction in Bipalium may be asexual or sexual and all species are hermaphroditic.

B. adventitium reproduces sexually and creates egg capsules, which hatch around 3 weeks post-deposition. The egg capsules have a tough exterior and generally contain multiple juveniles.[5]

B. kewense have rarely been observed using egg capsules as a primary method of reproduction. Asexual fragmentation is its main reproductive strategy in temperate regions and most individuals never develop sexual organs.[12] Juveniles of this species, unlike B. adventitium, do not appear the same coloration as parents in their early days.[13]

Toxicity

Recently, the presence of tetrodotoxin, a very potent neurotoxin, was recorded in B. adventitium and B. kewense.[14] It is the first record of tetrodotoxin in terrestrial invertebrates.

Species

The genus Bipalium includes the following species:

Invasive species

There is very little known about the ecology of terrestrial planarians, however research has been done on different genera and species, including several native and invasive species in Brazil,[15] Arthurdendyus triangulatus,[16] Rhynchodemus [17] and Bipalium.[18]

Currently, there are four known invasive species of Bipalium in the United States: B. adventitium, B. kewense, B. pennsylvanicum and B. vagum.[8] It is believed that these planarians came to the US on horticultural plants.

Bipalium kewense has been found commonly in American greenhouses since 1901.[19] This species is a voracious predator of earthworms, and has been identified a nuisance in the southern USA in earthworm-rearing beds.[20] Control of the species is difficult due to the lack of predators. As noted by the University of Florida IFAS department,

Other animals rarely devour land planarians, since surface secretions appear distasteful, if not toxic. Protozoans, including flagellates, ciliates, sporozoans, and nematodes have been detected in land planarians. Because of their cannibalistic habit, land planarians may be their own worst enemy.[21]

Individual Bipalium adventitium are characterized by a single dark dorsal stripe. They were first discovered in the US in California and New York[22] but have been found in Illinois[23] as well as most northern states[5] Bipalium kewense have five dark dorsal stripes and a partial dark collar. They have undergone several name changes since their discovery in North America. B. kewense is commonly found across the southern regions of the US.[13] B. kewense is found worldwide in tropical and subtropical regions.[12] Bipalium pennsylvanicum is characterized by its dark brown head and three dorsal stripes. Thus far it has only been found in Pennsylvania and in coastal South Carolina in 2014.[24] Bipalium vagum is characterized by two dark dorsal blotches on the head, a thick black band around the neck and three dark dorsal stripes. This species has recently been found in several Gulf Coast states.[8]

  • Bipalium kewense sighted in Austin, Texas
    Bipalium kewense sighted in Austin, Texas
  • Close up of head of Bipalium kewense
    Close up of head of Bipalium kewense
  • Specimen of Bipalium found in Georgia, United States
    Specimen of Bipalium found in Georgia, United States
  • Hammerhead worm found in Kerala, India
    Hammerhead worm found in Kerala, India
  • Hammerhead worm found in Chennai, India
    Hammerhead worm found in Chennai, India
  • Video of a Bipalium sp. from Mérida, Yucatán, Mexico

References

  1. ^ Stimpson (1857). "Prodromus descriptionis animalium evertebratorum quæ in Expeditione ad Oceanum, Pacificum Septentrionalem a Republica Federata missa, Johanne Rodgers Duce, observavit er descripsit. Pars I. Turbellaria Dendrocœla." Proc. Acad. nat. Sci. Philad. 1857: 25.
  2. ^ Curtis, S.K., R.R. Cowden, J.D. Moore, and J.L. Robertson. 1983. Histochemical and ultrastructural features of the epidermis of land planarian Bipalium adventitium. J. of Morphology 175: 171-194.
  3. ^ Ogren, R.E. 1985. The human factor in the spread of an exotic land planarian in Pennsylvania. Proc. of the Penn. Acad. of Sci. 59: 117-118.
  4. ^ Filella-Subira, E. (1983). «Nota sobre la presència de la planària terrestre Bipalium kewense Moseley, 1878 a Catalunya». Butll. Inst. Cat. Hist. Nat., 49: 151
  5. ^ a b c Ducey, P. K.; West, L. J.; Shaw, G.; De Lisle, J. (2005). "Reproductive ecology and evolution in the invasive terrestrial planarian Bipalium adventitium across North America". Pedobiologia. 49 (4): 367. doi:10.1016/j.pedobi.2005.04.002.
  6. ^ Stimpson, W. (1861). "On the genus Bipaliura". American Journal of Science and Arts, series 2. 31: 134–135.
  7. ^ Ogren, R. E. (1995). "Predation behaviour of land planarians". Hydrobiologia. 305: 105–111. doi:10.1007/BF00036370.
  8. ^ a b c Ducey, P. K., M. McCormick, and E. Davidson. 2007. Natural history observations on Bipalium cf. vagum Jones and Sterrer, 2005 (Platyhelminthes: Tricladida), a terrestrial broadhead planarian new to North America. Southeastern Naturalist.
  9. ^ Fiore, C.; Tull, J. L.; Zehner, S.; Ducey, P. K. (2004). "Tracking and predation on earthworms by the invasive terrestrial planarian Bipalium adventitium (Tricladida, Platyhelminthes)". Behavioural Processes. 67 (3): 327–334. doi:10.1016/j.beproc.2004.06.001. PMID 15518983.
  10. ^ Ducey, P. K.; Messere, M.; Lapoint, K.; Noce, S. (1999). "Lumbricid Prey and Potential Herpetofaunal Predators of the Invading Terrestrial Flatworm Bipalium adventitium (Turbellaria: Tricladida: Terricola)". The American Midland Naturalist. 141 (2): 305. doi:10.1674/0003-0031(1999)141[0305:LPAPHP]2.0.CO;2.
  11. ^ Dindal, D.L. 1970. Feeding behavior of a terrestrial turbellarian Bipalium adventitium. The American Midland Naturalist 83(2): 635-637.
  12. ^ a b Winsor, L. 1983. A revision of the cosmopolitan land planarian Bipalium kewense Moseley, 1878 (Turbellaria: Tricladida: Terricola). Zool. J. of the Linnean Soc. 79: 61-100.
  13. ^ a b Ducey, P. K.; Cerqua, J.; West, L. J.; Warner, M. (2006). Eberle, Mark E (ed.). "Rare Egg Capsule Production in the Invasive Terrestrial Planarian Bipalium Kewense". The Southwestern Naturalist. 51 (2): 252. doi:10.1894/0038-4909(2006)51[252:RECPIT]2.0.CO;2.
  14. ^ Stokes, A. N.; Ducey, P. K.; Neuman-Lee, L.; Hanifin, C. T.; French, S. S.; Pfrender, M. E.; Brodie, E. D.; Brodie Jr., E. D. (2014). "Confirmation and Distribution of Tetrodotoxin for the First Time in Terrestrial Invertebrates: Two Terrestrial Flatworm Species (Bipalium adventitium and Bipalium kewense)". PLoS ONE. 9 (6): e100718. doi:10.1371/journal.pone.0100718.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  15. ^ Leal-Zanchet, A. M.; Baptista, V.; Campos, L. M.; Raffo, J. F. (2011). "Spatial and temporal patterns of land flatworm assemblages in Brazilian Araucaria forests". Invertebrate Biology. 130: 25. doi:10.1111/j.1744-7410.2010.00215.x.
  16. ^ Jones, H. D. and B. Boag. 2001. The invasion of New Zealand flatworms. Glasgow Naturalist 23(supplement):77-83.
  17. ^ Ogren, R.E. 1955. Ecological observations on the occurrence of Rhynchodemus, a terrestrial turbellarian. Transactions of the American Microscopical Society 74: 54-60.
  18. ^ Ducey, P. K., and S. Noce. 1998. Successful invasion of New York State by the terrestrial flatworm, Bipalium adventitium. Northeastern Naturalist 5(3):199-206.
  19. ^ Esser, R. P. 1981. Land Planarians (Tricladida: Terricola). Contribution no. 227, Bureau of Nematology, Florida Department of Agricultural and Consumer Services, Division of Plant Industry, Gainesville, Fl.
  20. ^ Hyman, L. H. 1951. The Invertebrates: Platyhelminthes and Rhynchocoela the acoelomate Bilateria, McGraw-Hill Book Co., London, 550 p.
  21. ^ Choate, P.M., and Dunn, R.A., 1988. Land Planarians, Bipalium kewense Moseley and Dolichoplana striata Moseley (Tricladida: Terricola),IFAS Document EENY-049. Online:Available http://edis.ifas.ufl.edu/pdffiles/IN/IN20600.pdf
  22. ^ Hyman, L.H. 1954. Some land planarians of the United States and Europe, with remarks on nomenclature. American Museum Novitates (1667): 1-21.
  23. ^ Zaborski, E. 2002. Observations on feeding behavior by the terrestrial flatworm Bipalium adventitium (Platyhelminthes: Tricladida :Terricola) from Illinois. Am. Midl. Nat. 148: 401-408.
  24. ^ Ogren, R.E. 1987. Description of a new three-lined planarian of the genus Bipalium (Turbellaria: Tricladida) from Pennsylvania, U.S.A. Trans. Am. Microsc. Soc. 106(1): 21-30.
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