The embryology of Anthopleura elegantissima and Anthopleura xanthogrammica is described. Ova of A. elegantissima are 120–150 μm in diameter and brown, while those of A. xanthogrammica are 175–225 μm in diameter and purple. In both species, cleavage is complete and equal: endoderm formation is by emboly. The planulae of both species are similar in appearance and are 150–250 μm in length with an apical tuft 60–75 μm in length. Feeding of the planulae is discussed, as is the function and phylogenetic significance of the apical sensory tuft of the planula.
SUMMARY
A new parasitic dinoflagellate, Haplozoon axiothellae sp. nov., is described from the intestine of the marine polychaete Axiothella rubrocincta. The parasites are 40–175 μm long with 2–26 cells arranged in single or double rows. Two cytoplasmic inclusions previously unknown in this genus are described. The first is globular and varies in size, while the second is approximately 2 μm long and peanut‐shaped. The function and composition of the inclusions are unknown. Nuclear structure and karyokinesis are apparently different from those of typical dinoflagellates.
The Actiniidae is the largest and most diverse of the families of sea anemones (Anthozoa: Actiniaria). In addition to the morphological diversity within this family, there is considerable diversity in larval development. The Actiniidae are generally considered to be highly advanced anemones, although Hand ( 1966) has argued that this family should be considered primitive.
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