∞ generated and posted on 2016.11.11 ∞
Triploblastic animals that lack body cavities.
That is, acoelomates can be viewed as members of kingdom Animalia that lack coeloms despite possessing mesodermal tissue. As such, acoelomates include particularly the flatworms, that is, members of phylum Platyhelminthes. See also phylum Nemertea.
Note that diploblastic animals can be considered to be neither acoelomates nor coelomates since they also lack mesodermal tissue. One can find, however, members of phylum Cnidaria as well as phylum Ctenophora included among the acoelomates.
The parazoans (sponges), however, though they also lacking coeloms certainly cannot be described as acoelomates since they lack true tissues altogether.