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The ecdysozoans lack locomotory cilia and produce mostly amoeboid sperm, and their embryos do not undergo spiral cleavage as in most other protostomes. Ancestrally, the group exhibited sclerotized teeth within the foregut, and a ring of spines around the mouth opening, though these features have been secondarily lost in certain groups.
Uncus dzaugisi is an extinct species of animal which lived approximately 560 to 550 Ma ago during the late Ediacaran of Southern Australia.Its morphology suggests that it was a member of Ecdysozoa, which would make it the oldest member of the clade known so far, [1] as well as one of the oldest known bilaterians.
Priapulus caudatus is one of only nineteen known species in the phylum Priapulida. [2] French naturalist Jean-Baptiste Lamarck first described it in 1816. [1] Phylogenetic studies have indicated that scalidophorans, to which priapulids belong, are a basal clade of ecdysozoans (animals that grow by shedding their exoskeleton), and thus a sister group to all other ecdysozoans, an assortment ...
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Scalidophora is a group of marine pseudocoelomate ecdysozoans that was proposed on morphological grounds to unite three phyla: the Kinorhyncha, the Priapulida and the Loricifera. [2] [3] The three phyla have four characters in common — chitinous cuticle that is moulted, rings of scalids on the introvert, flosculi, and two rings of introvert ...
Adult Rhopalomyia solidaginis fly, emerging from pupal case Process of ecdysis of a cicada.. Ecdysis is the moulting of the cuticle in many invertebrates of the clade Ecdysozoa.
In protostomes, during gastrulation, the first opening becomes the embryos' mouth while the anus is formed later. Also, the secondary body cavity (shown in blue) forms from tissue that splits away from the rest, instead of by folding in from the gut walls.
The Spiralia are a morphologically diverse clade of protostome animals, including within their number the molluscs, annelids, platyhelminths and other taxa. [4] The term Spiralia is applied to those phyla that exhibit canonical spiral cleavage, a pattern of early development found in most members of the Lophotrochozoa.