Phylum Acanthocephala: A Phylogenetic Tree of Mutual Hosts



Many taxonomic studies have revealed the close relationship of Acanthamocephala to several other taxa. However, the precise species relationships and taxonomic consensus are still absent. Three separate conclusions have been drawn from morphological and molecular data and these include a synonym in Acanthamoeba, the first family of the true butterflies, and other squids. In addition, Phylum Acanthocephala is a monophyletic taxon and includes all the presently known true butterflies and their relatives. The present study intends to clarify the relationship among various acanthocephala species.

Assigned to the family of the butterflies

Acanthocephala larvae have been tentatively assigned to the family of the butterflies based on their external appearance. These include: Anemone Acanthocephala (synonymous with Anemone Multiceps), Dyscophecium Anemone (synonymous with Dyscophecium Metaphyschidum), and Allocoryne Multiceps. To support these tentatively derived conclusions, detailed morphometric data were taken from an extensive sample consisting of fully grown adults and larvae. Molecular analyses confirmed a robust association between Acanthocephala parae and the saurid genus Metaphylion (Kleen), the true butterflies of the subfamily Colothodes.

Relationships between Acanthocephala and other squids

Relationships between Acanthocephala and other squids are poorly known and are currently only speculative based on morphological evidence alone. The proposed hypothesis of a strict relationship between Acanthocephala and Metaphylion (Kleen) based on molecular data is therefore based on limited evidence and is therefore not universally accepted. One reason for the lack of acceptance is that the entire molecular tree of metathesis has so far remained unassembled and is still under investigation. Another problem facing attempts to link acanthocephala to other squids is the extreme level of negative morphological variation seen in this genus. Even if all previously known representatives of the subfamily Metaphylidae are considered, the exact relationship of acanthocephala to any other members is uncertain and the precise origin of this butterfly is currently unknown.


Recent studies have attempted to solve the mystery surrounding the relationship of acanthocephala to other closely related but enigmatic organisms by comparing the virulence and anti-parasite properties of several common parasites. Several representatives of the phylum Prototheria have been found to be immune to certain parasites. Using a well-characterized laboratory strain of the whip worm Trichophyton, researchers identified anti-parasitic properties of the paraeotheroid gland of Acanthocephala. They identified specific proteins by immunofluorescence, revealing that these proteins recognize and bind the parasite’s antigens and that they trigger an inflammatory response from the paraeotheroid gland.


The analysis also revealed the specific amino acid residues required for the immune complexes to be able to recognize the worm’s eggs. This means that the parasitic species may not be aware of the presence of their own eggs, leading to additional selective breeding and the generation of larger numbers of susceptible individuals. The study is preliminary and needs to be backed up with further research, but it does provide strong evidence that Acanthocephala sp. may be prone to several parasites, including white-flies, aegyptiaca, tapeworms, and possibly more. The results suggest that further research is needed to verify these relationships and to determine if any other well known worms have specific mechanisms of protection against other parasites.

Development of acanthocephala

The study looked only at the growth and development of acanthocephala, a small member of the phylum Vermifera. In addition to this, the scientists involved in the study examined several other closely related vermiferous animals, including dogs, cats, and horses. It was found that all the animals had nearly identical nervous systems, with the exception of the horses. Vermiferous animals are known to have diverse nervous systems and the researchers believe that this unique feature may help them evade parasitization by more common intestinal predators.

Study of Vermiferous

The study of Vermiferous animals confirms earlier studies that Acanthocephala sp. does have a specialized intestinal tract and the animals in this phylum share several characteristics with other invertebrates such as chitons, cephalopods, and tunicates. They have both an oral cavity as well as the olfactory sense. Vermiferous sponges also appear to have a form of life cycle that involves the presence of eggs in their shells.


The study of Vermiferous animals supports the hypothesis that Acanthocephala is a monophyletic group of ciliate organisms. The sister groupings of Acanthocephala (osteichthyoid fishes, cephalopods and metathesis) are hypothesized to be a result of a recent horizontal evolution of these animals from their ancestral land-based relatives. The analysis of morphological and molecular data does support this hypothesis. In addition, molecular evolutionary studies have found that Acanthocephala belong to the class of ciliate that are most closely related to the group of rotifers.

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