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Indication of an Anal Pore in Gnathostomulida
Author(s) -
KNAUSS ELIZABETH B.
Publication year - 1979
Publication title -
zoologica scripta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.204
H-Index - 64
eISSN - 1463-6409
pISSN - 0300-3256
DOI - 10.1111/j.1463-6409.1979.tb00630.x
Subject(s) - biology , epidermis (zoology) , dorsum , connection (principal bundle) , anatomy , basement membrane , electron microscope , microbiology and biotechnology , geometry , physics , mathematics , optics
Two species of Haplognathia (Gnathostomulida, Filospermoidea) were examined by electron microscopy and found to possess a tissue connection between the posterior end of the intestine and the dorsal epidermis. This anal tissue connection is characterized by a thinned out epidermis, interdigitation of epidermal and intestinal cells, and the absence of the basement membrane. An open anal pore was not observed. It is possible that the anal tissue connection of Haplognathia serves as a functional anal pore. The implications of this discovery with respect to the various theories of early Metazoan evolution are discussed.