A small phylum of parasitic invertebrates that comprises the thorny-headed worms.
'Because the new taxon lacks syncytia, a key character for the Rotifera and Acanthocephala, the Micrognathozoa cannot be included in Syndermata.'
'Traditionally, the taxonomic groups in Acanthocephala have been identified based on morphological features and host characteristics.'
'The shift between aquatic and terrestrial hosts in Acanthocephala is probably driven by availability of appropriate arthropod intermediate hosts in the particular habitat.'
'Although the ICL has little taxonomic significance, it is synapomorphic with phylum Acanthocephala, indicating a close phylogenetic relationship.'
'Perversely, they failed to include any sequences from rotifers, gnathostomulids, chaetognaths, or, in fact, anything that might actually be comparable to Acanthocephala.'
'The sister - group relationship between Gnathostomulida and Rotifera + Acanthocephala was first mentioned by Rieger and Tyler.'
'Significant amounts of character loss versus character innovation is expected if the evolution of parasitism in Acanthocephala is truly ‘degenerative.’'
'Also, within Acanthocephala there have been multiple shifts between aquatic and terrestrial intermediate and definitive hosts.'
'However, the relationship between Rotifera and Acanthocephala has not been resolved.'
((n. pl.) A group of intestinal worms, having the
proboscis armed with recurved spines.)
Origin:
Modern Latin (plural), from acantho- ‘thornlike’ + Greek kephalē ‘head’.
