200 mm) sipunculan, Xenosi phon branchiatus were also found in the Cocorocas samples.
nudus is a sipunculan that has been known to scientists since Linnaeus described this species in 1766 (Hyman, 1959).
The biota includes sponges, sea pens, brachiopods, priapulid and sipunculan
worms, onycophorans, many diverse arthropods, sea cucumbers, stalked echinoderms, and chordates.
This cuticle resembles those of some polychaetes, including sipunculan
pelagophaeras, that retain the egg envelope into the larval stages (17), (18).
PCB concentrations in intertidal sipunculan
(Phylum Sipuncula) marine worms from the Pacific coast of Costa Rica.
Although this issue is not yet settled, data on neurogenesis indeed show remnants of an ancestral segmented bodyplan in the sipunculan larva (Kristof et al.
A recent study on sipunculan neurogenesis revealed that the larvae of this taxon undergo cryptic segmentation by forming a paired ventral nerve cord with associated, subsequently appearing, segmental commissures and four pairs of perikarya (Kristof et al.
Given the importance of a homeostatic balance of apoptosis in immunity, regulation of coelomocyte apoptosis could be significant to the sipunculan
immune system, and several environmental factors could have an impact on the coelomocytes, thus triggering the apoptotic program.
Our survey encompasses annelid, brachiopod, echinoderm, echiuran, molluscan, priapulid, and sipunculan
representatives among the invertebrates (Table 1), as [TABULAR DATA FOR TABLE I OMITTED] well as a wide range of vertebrates including fish, amphibians, reptiles, birds, newborn marsupials, and placental mammals (Cohen and Nemhauser, 1985; Cohen et al.
Bivalve relative abundance increases and sipunculan
relative abundance decreases with increasing site degradation.
Cellular defense reactions of Phascolosoma agassizii, a sipunculan
worm: phagocytosis by granulocytes.
Coral borers of the eastern Pacific: the sipunculan