''Australamphilina elongata'' is a species of

parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson ha ...

worm in the order

Amphilinidea Amphilinidae is a family of parasitic flatworms of the phylum Platyhelminthes. It is the only family in the monotypic order Amphilinidea. Amphilinids are Cestodes, yet differ from true tapeworms (Eucestoda) as their bodies are unsegmented and not ...

. Amphilinids are commonly considered to be

tapeworm Eucestoda, commonly referred to as tapeworms, is the larger of the two subclasses of flatworms in the class Cestoda (the other subclass is Cestodaria). Larvae have six posterior hooks on the scolex (head), in contrast to the ten-hooked Cesto ...

s, yet differ from true tapeworms, subclass

Eucestoda Eucestoda, commonly referred to as tapeworms, is the larger of the two subclasses of flatworms in the class Cestoda (the other subclass is Cestodaria). Larvae have six posterior hooks on the scolex (head), in contrast to the ten-hooked Cestod ...

, because their bodies are unsegmented and are not divided into

proglottid Cestoda is a class of parasitic worms in the flatworm phylum (Platyhelminthes). Most of the species—and the best-known—are those in the subclass Eucestoda; they are ribbon-like worms as adults, known as tapeworms. Their bodies consist of ...

s. It is an internal parasite of freshwater turtles including the

eastern long-necked turtle The eastern long-necked turtle (''Chelodina longicollis'')Kennett, R., Roe, J., Hodges, K., and Georges, A. 2009. ''Chelodina longicollis'' (Shaw 1784) – eastern long-necked turtle, common long-necked turtle, common snake-necked turtle. ''In'': ...

(''Chelodina longicollis''). It is found in eastern Australia.

Description

Unlike other tapeworms, the body of amphilinids is not divided into segments, instead being leaf-shaped and laterally flattened. There is a proboscis and several frontal glands at the anterior end, and an ovary and a seminal receptacle at the posterior end. The uterus extends from the posterior end, forward to the anterior end, back to the posterior end and then forward again to the anterior end, before opening at the female gonopore. Small testes and yolk cells are scattered throughout most of the tissue. The male gonopore is at the posterior end, and there is no gut. The larvae have ten wrench-shaped hooks and these are retained at the posterior end of the adult body. ''A. elongata'' is bright yellow and can grow to a length of and a width of .

Life cycle

The adult stage of this tapeworm is found in the body cavity of the

(''Chelodina longicollis''), and there may be as many as thirty worms in one turtle host. It is uncertain how the worm's eggs are released into the open water, but somehow they do emerge. When the eggs hatch, the developing larvae seek out an intermediate host, a suitable freshwater crayfish, and penetrate its cuticle by chemical action and by sawing through the shell with miniature hooks. The young tapeworm then continues its development in the crustacean, and if the crayfish is eaten by a turtle, the larva forces its way through the turtle's

oesophagus The esophagus (American English) or oesophagus (British English; both ), non-technically known also as the food pipe or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to th ...

into the turtle's body cavity.

References

{{Taxonbar, from=Q55604498 Cestoda Animals described in 1931