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Bipalium
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Genus of flatworms
{{cite journal |last1=Stimpson |author-link=William Stimpson |year=1857 |title=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 |journal=Proceedings of the Academy of Natural Sciences of Philadelphia |volume=9 |page=25 |jstor=4059187 }}"},"type_species":{"wt":"''[[Bipalium fuscatum]]''"},"type_species_authority":{"wt":"Stimpson, 1857"},"synonyms":{"wt":"*''Sphyrocephalus'' Schmarda, 1859\n*''Dunlopea'' Wright, 1860\n*''Bipaliura'' Stimpson, 1861\n*''Perocephalus'' [[Ludwig von Graff|von Graff]], 1896 (in part)\n*''Placocephalus'' [[Ludwig von Graff|von Graff]], 1896 (in part) \n*''Sphaerocephalus'' Loman, 1888"}},"i":0}}]}'>
Bipalium
Model of Bipalium strubelli
Scientific classification
Kingdom:<br>Animalia
Phylum:<br>Platyhelminthes
Order:<br>Tricladida
Family:<br>Geoplanidae
Subfamily:<br>Bipaliinae
Genus:<br>Bipalium<br>Stimpson, 1857[1]
Type species
Bipalium fuscatum<br>Stimpson, 1857
Synonyms
Sphyrocephalus Schmarda, 1859
Dunlopea Wright, 1860
Bipaliura Stimpson, 1861
Perocephalus von Graff, 1896 (in part)
Placocephalus von Graff, 1896 (in part)
Sphaerocephalus Loman, 1888
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", a highly ciliated region on the ventral epidermis that helps them to creep over the substrate.[2] Native to Asia, several species are invasive to the United States,[3] Canada, and Europe.[4][5] Some studies have begun the investigation of the evolutionary ecology of these invasive planarians.[6]
Etymology<br>[edit]
The name Bipalium comes from Latin bi-, "two" + pala, "shovel" or "spade", because species in this genus resemble a pickaxe.[7]
Description<br>[edit]
The genus Bipalium was initially defined by Stimpson to include land planarians with the head broadened, forming a head plate. Later, in 1899, Ludwig von Graff divided it into three genera according to the shape of the head:[8]
Bipalium: with a well-developed head plate, much broader than long, and with elongated lateral auricles
Perocephalus: rudimentary head plate, not much broader than the body
Placocephalus: flat head plate with a circular outline
Josef Müller, in 1902, considered that no sufficient anatomical basis existed for this distinction, and reunited them under Bipalium. Later, von Graff accepted Müller's conclusions.[8]
Towards the end of the 20th century, Robert E. Ogren and Masaharu Kawakatsu started a series of publications called "The Land Planarian Index series" in which they reviewed and organized all taxonomic information regarding land planarians. At first, they retained all broad-headed planarians in the genus Bipalium, but later split them into four genera based on the anatomy of the reproductive organs: Bipalium, Novibipalium, Humbertium, and Diversibipalium.[9]
Under this scenario, the genus Bipalium is defined as containing broad-headed land planarians with simple copulatory organs, without accessory ducts or copulatory bursa, and with a fold of tissue separating the male and female exit ducts.[9]
Feeding habits<br>[edit]
Bipalium species are predatory. Some species prey on earthworms, while others may also feed on mollusks.[10][11] These flatworms can track their prey.[12] When captured, earthworms begin to react to the attack, but the flatworm uses the muscles in its body, as well as sticky secretions, to attach itself to the earthworm to prevent escape. The planarians cover, or cap, the prostomium, peristomium, and anterior end to stop the violent reaction by the earthworm.[13]
To feed on their prey, species of Bipalium often evert their pharynges from their mouths, located on the midventral portion of their bodies, and secrete enzymes that begin the digestion of the prey. The liquefied tissues are sucked into the branching gut of the flatworms by ciliary action.[14]
Reproduction<br>[edit]
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.[6]
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.[15] Juveniles of this species, unlike B....