Here we report the effect of food concentration on the recovery from anhydrobiosis of a bdelloid rotifer, Macrotrachela quadricornifera. Cohorts were either starved, or fed high or low concentrations of food, before being dried and their subsequent recovery rates determined. The rotifers starved for 3 d before anhydrobiosis recovered in significantly higher proportion, and those fed lower food concentration recovered better than those fed higher food concentration. In addition, starvation did not decrease the recovery of other bdelloid species (Philodina roseola and Adineta sp.1) which were either fed or starved before anhydrobiosis. These results suggest that a successful recovery from anhydrobiosis is not dependent on prior resource level supplied to the bdelloids. However, the lack of resources might not be the only factor in a successful recovery from anhydrobiosis. Observations using scanning electron microscopy of fed individuals of M. quadricornfera entering anhydrobiosis showed that some food remained in the digestive tract. Thus, we propose that the negative effect of rich food may be due to a purely mechanical effect and may be interfering with a proper folding of the rotifer body at the onset of anhydrobiosis. This contribution results from studies carried out in preparation for biological experiments scheduled on the International Space Station (ISS).

We report on a study of reproduction and development in the Mediterranean vermetid gastropod Vermetus triquetrus from the SE coast of Spain. It is a gonochoristic species. The egg capsules are attached to the inside of the shell, and females brood up to 22 capsules simultaneously (more often 4-10). The capsules hold 10-61 eggs or embryos; the uncleaved eggs are yolk-rich, with a mean diameter of 377.3 µm. A distinct polar lobe occurs during the first cleavage, and blastomere D has discernible qualities after the 4-cell stage. The formation of the mesentoblast 4d occurs at the transition from the 24-cell stage to the 25-cell stage. Gastrulation begins after the 36-cell stage. Internal yolk is the major source of nutrition for the encapsulated embryos, but some nurse eggs (∼12%))and some sibling larvae are also ingested by the developing embryos. Hatching occurs during the swimming/crawling pcdiveliger stage, and metamorphosis is completed outside the capsules soon after hatching. Hence. larval development in Vermetus triquetrus is lecithotrophic intracapsular, with a short free-swimming/crawling phase.

The albumen gland of the freshwater pulmonate snail Helisoma duryi produces and secretes the perivitelline fluid, which coats fertilized eggs and provides nutrients to the developing embryos. It is known that perivitelline fluid secretion is stimulated by dopamine through the activation of a dopamine D₁-like receptor, which in turn stimulates cAMP production leading to thc secretion of perivitelline fluid. This paper examines the glandular release of perivitellinc fluid and provides evidence for the role of Ca² in the regulated secretion of perivitelline fluid based on protein secretion experiments and inositol 1,4,5-trisphosphate assays. Dopamine-stimulated protein secretion by the albumen gland is reduced in Ca²⁺-free medium or in the presence of plasma membrane Ca²⁺ channel blockers, although the Ca²⁺ channel subtype involved is unclear. In addition, dopamine-stimulated protein secretion does not directly involve phospholipase C-generated signaling pathways and Ca²⁺ release from intraeellular stores. Sarcoplasmic/endoplasmic reticulum Ca²⁺-ATPase inhibitors had little effect on protein secretion when applied alone; however, they potentiated dopamine-stimulated protein secretion. Dantrolene, an inhibitor of ryanodine receptors, 8-(N, N-diethylamino)-octyl-3,4,5-trimethoxybenzoate hydrochloride, a nonspecific inhibitor of intracellular Ca²⁺ channels, and 2-aminoethyldiphenylborate, an inhibitor of inositol 1,4,5-trisphosphate receptors, did not suppress protein secretion, suggesting Ca²⁺ release from internal stores does not directly regulate protein secretion. Thus, the influx of Ca²⁺ from the extracellular space appears to be the major pathway mediating protein secretion by the albumen gland. The results are discussed with respect to the role of Ca²⁺ in controlling exocytosis of proteins from the albumen gland secretory cells.

The outer surfaces of the shells of living marine gastropods are often colonized by other organisms. However, only one species, the sabellid worm Terebrasabella heterouncinata, is able to settle in the aperturc of living gastropods. Native to South Africa, and introduced to California. this worm is a pest of abalone aquaculture and has been a threat to native gastropods in California. We investigated the intrinsic susceptibility of 15 marine gastropods from California to this apertural fouling organism. Intrinsic susceptibility was significantly different among gastropod species. Overall, caenogastropods tended to be more resistant than were the vctigastropods and patellogastropods. This suggests that variability in susceptibility could be due to characteristics associated with closely related gastropod hosts. However, this only partially explained the variation in susceptibility to individuals of T. heterouncinata. Intrinsic susceptibility was not associated with potential host species from similar habitats. We discuss host susceptibility to T. heterouncinata, including implications for potential control of this pest species, and for understanding factors enabling this polychaete to inhabit the apertural region, an area typically free of all other epibionts.

Lateral flagella of the antennules of scyllarid lobsters were examined for setal morphology and distribution via scanning electron microscopy. Setal distribution patterns were mapped directly for 3 regions of the antennule (base, tuft, and tip) and analyzed for differences: (1) between left and right antennules, (2) between males and females within a species, and (3) among species by comparing counts of setae per annulus in the ventral tuft region only. Six types of antennular setae were identified based on their external morphology: aesthetascs, simple, modified simple, asymmetric, hemi-plumose, and toothbrush seiae. These different types were organiLed in a clear pattern over the ventral and dorsal surfaces of the lateral flagella of the antennulc. Aesthetasc, asymmetric, modified simple, and hemi-plumose setae were found only on annuli in the tuft region between the distal add proximal ends of the flagellum. Simple setae were found on all annuli of all regions of the antennule, and toothbrush setae were mainly concentrated on all annuli of the base region and on proximal annuli of the tuft region. All species of scyllarids examined had the same general pattern of setal distribution and no differences were found between left and right, or male and female antcnnules. Similar setae located on the lateral antennules of species from the families Nephrophidae and Palinuridae (clawed and spiny lobsters) have been previously described as chemo- and/or mechanoreceptive for use in distance chemoreception (i.e., detection and orientation to olfactory stimuli). Based on work on clawed and spiny lobsters, we predict that the aesthetascs on slipper lobsters have a chemoreceptive function and that simple and toothbrush setae may have a bimodal chemo- and mechanoreceptive function.

Historically, characters from early animal development have been a potentially rich source of phylogenetic information, but many traits associated with the gametes and larval stages of animals with complex life cycles are widely suspected to have evolved frequent convergent similarities. Such convergences will confound true phylogenetic relationships. We compared phylogenetic inferences based on early life history traits with those from mitochondrial DNA sequences for sea stars in the genera Asterina, Cryptasterina, and Patiriella (Valvatida: Asterinidae). Analysis of these two character sets produced phylogenies that shared few clades. We quantified the degree of homoplasy in each character set when mapped onto the phylogeny inferred from the alternative characters. The incongruence between early life history and nucleotide characters implies more homoplasy in the life history character set. We suggest that the early life history traits in this case are most likely to be misleading as phylogenetic characters because simple adaptive models predict convergence in early life histories. We show that adding early life history characters may slightly improve a phylogeny based on nucleotide sequences, but adding nucleotide characters may be critically important to improving inferences from phylogenies based on early life history characters.

The spine morphology of all established species of Diadema and Echinothrix, including 2 color morphs of E. calamaris, were examined externally and internally via transverse sectioning to identify diagnostic species features and to assess the morphological relationship between species. Forty-nine different morphological characters were measured and analysed using ordination by multi-dimensional scaling (MDS) and cluster analysis. Specimens of Diadema paucispinum and D. setosum had very distinct spine structures. In D. paucispinum, the spines were more robust than those of other species of Diadema. This was evident in the spine's internal structure, with large, closely packed solid wedges, a small axial cavity, and rings of trdbeculae throughout the spine's length. The spines in D. setosum were distinctive because of their length in relation to test size and the reduced flaring of their verticillations. The spines of other members of this genus were very similar to each other. Without careful sectioning, the spines from specimens of D. antillarurn, D. ascensionis, D. mexicanurn and D. savignyi were difficult to differentiate. The internal structures of spines for each species did, however, possess a combination of features that differentiated the species. Such features included the shape, orientation, and number of solid wedges, the presence or absence of spokes and rings of trabeculae between the solid wedges, and the presence or absence of tissue within the axial cavity. Individuals of Diadema palmeri also had spines morphologically similar to other species, however, the red pigmentation of these spines (in life and when preserved) made them easily distinguishable. The spine structures of the 2 species of Echinothrix were starkly different, while the white and brown color morphs of E. calamaris had morphologically distinctive ambulacral and interambulacral spines. The blunt, open-tipped interambulacral spines, with reticular tissue present in the axial cavity of the white color morph, were easily distinguished from the pointed, closed-tipped spines, with a hollow axial cavity found in the brown color morph. Such differences indicate that the brown color morph is either a subspecies or a separate species. Taken together the data show that each species has significant morphological differences in the structure of the spines. It is evident from our data that spine morphology is a useful tool to differentiate these commonly confused species.