Gigantorhynchida is an order containing a single family, Gigantorhynchidae of

parasitic worm Parasitic worms, also known as helminths, are large Parasitism#Basic concepts, macroparasites; adults can generally be seen with the naked eye. Many are intestinal worms that are soil-transmitted helminth, soil-transmitted and intestinal parasit ...

s that attach themselves to the intestinal wall of terrestrial

vertebrates Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, ...

. Gigantorhynchida contains the following three genera: *''

Gigantorhynchus ''Gigantorhynchus'' is a genus of Acanthocephala (thorny-headed worms, also known as spiny-headed worms) that parasitize marsupials, anteaters, and possibly baboons by attaching themselves to the intestines using their hook-covered proboscis. Th ...

'' Hamann, 1892 :The genus ''Gigantorhynchus'' is characterized by the presence of a cylindrical proboscis with a crown of robust hooks at the

apex The apex is the highest point of something. The word may also refer to: Arts and media Fictional entities * Apex (comics), a teenaged super villainess in the Marvel Universe * Ape-X, a super-intelligent ape in the Squadron Supreme universe *Apex ...

followed by numerous small hooks on the rest of the proboscis. The body, or trunk, is long with pseudosegmentation, the lemnisci are

filiform Filiform, thread or filament like, can refer to: *Filiform, a common term used in botany to describe a thread-like shape *Filiform, or filiform catheter, a medical device whose component parts or segments are all cylindrical and more or less uni ...

, and the

testes A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testoster ...

are ellipsoid. Species of ''Gigantorhynchus'' are distinguished based on the number and size of hooks on the crown of the proboscis, the type of pseudosegmentation, and size of the ellipsoid eggs. Males of all species possess eight

cement glands Cement glands are small organs found in Acanthocephala that are used to temporarily close the posterior end of the female after copulation. Cement glands are also mucus-secreting organs that can attach embryos or larvae to a solid substrate. The ...

which are used to temporarily close the posterior end of the female after copulation. There is pronounced

sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...

with the female often two or more times longer than the male. *'' Intraproboscis'' *''

Mediorhynchus ''Mediorhynchus'' is a genus of small parasitic spiny-headed (or thorny-headed) worms. Phylogenetic analysis has been conducted on two known species of ''Mediorhynchus'' and confirmed the placement along with the related genus Gigantorhynchus in ...

Taxonomy

Notes

References