The group is named after the spines, scalids, covering the introvert, the head that can be retracted into the trunk.
ZoologyScalidophora are marine pseudocoelomate protostomes. They have chitinous cuticle that is moulted, rings of scalids on the introvert, flosculi, and two rings of introvert retracts.
TaxonomyThe monophyly of the
Scalidophora is not supported by molecular studies. The position of the
Loricifera was uncertain, or as sister to the Panarthropoda. Studies supported a reduced
Scalidophora comprising the
Kinorhyncha and
Priapulida as sister phyla. Their closest relatives are the Panarthropoda,
Nematoda and
Nematomorpha. Thus, they are placed in the group
Ecdysozoa. The group has also been considered a single group, Cephalorhyncha, with three classes.
SubclassesKinorhynchaPriapulidaLoricifera