''Australamphilina elongata'' is a species of

parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The ent ...

worm in the

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

Amphilinidea. 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 being Cestodaria). Larvae have six posterior hooks on the scolex (head), in contrast to the ten-hooked Ce ...

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 being Cestodaria). Larvae have six posterior hooks on the scolex (head), in contrast to the ten-hooked Ce ...

, because their bodies are unsegmented and are not divided into

proglottid Cestoda is a Class (biology), 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, commonly known as tapeworms. T ...

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

eastern long-necked turtle The eastern long-necked turtle (''Chelodina longicollis''), also known as the common long-necked turtle and common snake-necked turtle, is an east Australian species of snake-necked turtle that inhabits a wide variety of water bodies and is an ...

(''Chelodina longicollis''). It is found in eastern Australia. It is the only species in the genus ''Australamphilina''.

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 Crayfish are freshwater crustaceans belonging to the infraorder Astacidea, which also contains lobsters. Taxonomically, they are members of the superfamilies Astacoidea and Parastacoidea. They breathe through feather-like gills. Some spe ...

, and penetrate its

cuticle A cuticle (), or cuticula, is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticle" are non- homologous, differing in their origin, structu ...

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), oesophagus (British English), or œsophagus ( archaic spelling) ( see spelling difference) all ; : ((o)e)(œ)sophagi or ((o)e)(œ)sophaguses), colloquially known also as the food pipe, food tube, or gullet, ...

into the turtle's body cavity.

References

{{Taxonbar, from1=Q61493679, from2=Q55604498 Cestoda Taxa described in 1931