''Bipalium adventitium'' is a

land planarian Geoplanidae is a family of flatworms known commonly as land planarians or land flatworms. These flatworms are mainly predators of other invertebrates, which they hunt, attack and capture using physical force and the adhesive and digestive proper ...

in the subfamily Bipaliinae. It has been accidentally introduced in the United States, where it is considered

invasive Invasive may refer to: *Invasive (medical) procedure *Invasive species *Invasive observation, especially in reference to surveillance *Invasively progressive spread of disease from one organ in the body to another, especially in reference to cancer ...

Appearance

Most adult individuals of ''B. adventitium'' are in length. The head is expanded and fan-shaped, being easily distinguishable from other common species of ''Bipalium'', such as ''

Bipalium kewense ''Bipalium kewense'' is a species of large predatory land planarian with a cosmopolitan distribution. It is sometimes referred to as a "hammerhead flatworm" due to its half-moon-shaped head, but this name is also used to refer to other species in ...

'' and '' Bipalium pennsylvanicum'', because these have a head in the shape of a half moon. The body has a yellow to tan color and has one dark dorsal stripe that does not extend over the head.

Behaviour and Ecology

Predation

''Bipalium adventitium'' is known to prey on

earthworm An earthworm is a terrestrial invertebrate that belongs to the phylum Annelida. They exhibit a tube-within-a-tube body plan; they are externally segmented with corresponding internal segmentation; and they usually have setae on all segments. Th ...

s. In order to catch its prey, it follows a chemical trail given off by the earthworm. Chemoreceptors on the head are responsible for sensing the trail left by the prey. After finding an earthworm, the planarian quickly crawls over it and wraps itself around the prey, preventing its escape. In North America, where ''B. adventitium'' is an introduced species, most earthworms do not immediately recognize the flatworm as a predator. They try to escape only after being pierced by the planarian's everted pharynx, which is one of the reasons of ''B. adventitiums success in invading this continent. Recently, it has been confirmed that the potent

neurotoxin Neurotoxins are toxins that are destructive to nerve tissue (causing neurotoxicity). Neurotoxins are an extensive class of exogenous chemical neurological insultsSpencer 2000 that can adversely affect function in both developing and mature ner ...

tetrodotoxin Tetrodotoxin (TTX) is a potent neurotoxin. Its name derives from Tetraodontiformes, an order that includes pufferfish, porcupinefish, ocean sunfish, and triggerfish; several of these species carry the toxin. Although tetrodotoxin was discovered ...

is present in ''B. adventitium''. Its function is yet unknown, but it may be used as a defense against predators or as a way to subdue prey.

Reproduction

Differently from ''Bipalium kewense'', which usually reproduces asexually by fission, ''Bipalium adventitium'' more commonly reproduces sexually. It is suggested that it has only one breeding season per year. As in most land planarians, mating occurs by internal fertilization when two individuals meet. The eggs are deposited in egg capsules and after about 3 weeks they release 1–6 juveniles.

Invasion of North America

''Bipalium adventitium'' is believed to have been introduced in the last century to the United States from Asia. It is believed that this broadhead planarian was introduced and spread to most Northern states passively by human dispersal and has become abundant in the region it occupies. It is more commonly found in suburban areas and nurseries where exotic plants are prevalent. It is found in gardens and woodlands under objects like leaf litter, where the soil is moist. The ecological consequences of this invasion have not yet been fully explored. In 2019, the species has been recorded for the first time in

Montréal Montreal ( ; officially Montréal, ) is the second-most populous city in Canada and most populous city in the Canadian province of Quebec. Founded in 1642 as '' Ville-Marie'', or "City of Mary", it is named after Mount Royal, the triple-p ...

, Quebec, Canada.

References

{{Taxonbar, from=Q1932616 Geoplanidae