A new genus and species of Sphaeromatidae (Crustacea: Isopoda) with experiments and observations on its reproductive biology, interspecific interactions and color polymorphisms

The new genus, Paraleptosphaeroma, is distinguished from the morphologically similar genus Leptosphaeroma by the fusion of the pleonites, the shape of the peni, the attachment of appendix masculina, and the presence or the absence of an endopod on the first pleopod. The term cingula is introduced to refer to lateral margins fringed with setae and the distinction is drawn between setal and membranous forms of the cingula. Paraleptsphaeroma glynni (sp nov.) occurs on cobble in tidal pools and is associated with three sessile species, two bryozoans and a coralline alga. Experiments demonstrate the isopod to be a sequential hermaphrodite with a socially mediated sexual transformation. Brood mortality is very low. Observations of feeding and analysis of gut contents show anascan bryozoans to be the principal food sources of P. glynni. The principal color polymorphisms of juveniles are illustrated. The apparent concordance between these patterns and those produced by the boring activities of phoronids and barnacles is tested, with results suggesting that the color patterns are adaptations to concealment from fish predators. This interpretation is further supported by morphological evidence and experiments demonstrating the poor swimming ability of P. glynni

Ultrastructure of metamorphosis in Hydractinia echinata

The fine structure of metamorphosis in the athecate hydroid, Hydractinia echinata, is described. Metamorphosis was induced in two ways: by exposing planulae to appropriate microflora and by temporary exposure to an ionic imbalance. Larvae induced to metamorphose by ionic imbalance differed considerably in behavior, but little in fine structure, from those induced by microflora. Metamorphosis was initiated by the discharge of nematocysts and loss of neurosensory cells, followed by secretion of mucus from gland cells and dense-staining granules from supportive cells. Associated with these events is a severe folding of the larva and permanent adherence of the larva to the substratum by its anterior end. Following movement of remaining gland cells across the mesoglea into the endoderm-and movement of interstitial cells into the ectoderm, the metamorphosing planula extends tentacle rudiments and stolonal buds, eventually elongating into a primary polyp

酵素の作用(退官記念最終講義)

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Genetic Background and Allorecognition Phenotype in Hydractinia symbiolongicarpus

The Hydractinia allorecognition complex (ARC) was initially identified as a single chromosomal interval using inbred and congenic lines. The production of defined lines necessarily homogenizes genetic background and thus may be expected to obscure the effects of unlinked allorecognition loci should they exist. Here, we report the results of crosses in which inbred lines were out-crossed to wild-type animals in an attempt to identify dominant, codominant, or incompletely dominant modifiers of allorecognition. A claim for the existence of modifiers unlinked to ARC was rejected for three different genetic backgrounds. Estimates of the genetic map distance of ARC in two wild-type haplotypes differed markedly from one another and from that measured in congenic lines. These results suggest that additional allodeterminants exist in the Hydractinia ARC

The Evolution of Individuality

xv,197 hal,;ill,;25c

Yale Y Replicate 1

Contains sequential images of Yale logo experimental treatment, replicate