Environmental conditions can affect the morphology and distribution of sponges. In particular, depth is known to influence the morphology of shallow-water sponges; however, the influence of depth on deep-water sponges has never been investigated. Although boreal Geodiidae (Demospongiae, Astrophorida) are deep-water species, in fjords and along the Norwegian coast Geodia barretti, G. simplicissima, and Pachymatisma normani can occasionally be found at shallow depths (20–40 m). In this study, we examine new shallow specimens from the Norwegian coast to compare their morphological and molecular characteristics with those of their deep-water counterparts. Morphology was studied at the level of the organism, skeletal organization, and the spicules, and a fragment of the cytochrome oxidase 1 gene was sequenced for shallow and deep specimens. Twelve specimens of Geodia spp. and five specimens of P. normani were collected in shallow waters. The majority of the Geodia spp. were identified as G. simplicissima, a species that has not been reported since its original description in 1931. However, we propose that G. simplicissima, only found in shallow waters, is a junior synonym of G. barretti. When comparing shallow and deep-water specimens of G. barretti and P. normani, we found phenotypic differences with respect to color, external morphology, cortex organization, and, above all, spicule morphology. In shallow specimens, microrhabds, sterrasters, and triaenes were smaller and irregular or underdeveloped. Oxyasters and strongylasters were normal in form, but smaller. We hypothesize that the lower silica concentration in shallow waters is primarily responsible for the disruption of spiculogenesis in shallow-water specimens of G. barretti and P. normani. The underdeveloped sterrasters observed in shallow-water specimens provide new insights into the formation of these particular microscleres. Finally, we discuss how the colonization of shallow waters by deep-water sponges may have strongly influenced spicule evolution and speciation.

Coral planulae are induced to settle and metamorphose by contact with either crustose coralline algae or marine bacterial biofilms. Larvae of two coral species, Pocillopora damicornis and Montipora capitata, which respond to different metamorphic cues, were utilized to investigate the sensory mechanisms used to detect metamorphic cues. Because the aboral pole of the coral planula is the point of attachment to the substratum, we predicted that it is also the point of detection for cues. To determine where sensory cells for cues are localized along the body, individual larvae were transversely cut into oral and aboral portions at various levels along the oral–aboral axis, and exposed to settlement-inducing substrata. Aboral ends of M. capitata metamorphosed, while oral ends continued to swim. However, in larvae of P. damicornis, ¾ oral ends (i.e., lacking the aboral pole) were also able to metamorphose, indicating that the cells that detect cues may be distributed along the sides of the body. These cells do not correspond to FMRFamide-immunoreactive cells that are present throughout the body. Cesium ions induced both aboral and oral ends of larvae of both species to settle, suggesting that oral ends have not lost their capacity to metamorphose, despite lacking sensory cells to detect natural cues. To determine whether sensory cells in larvae of P. damicornis are restricted to one side of the body, swimming behavior over substrata was observed in larvae labeled with diI, a red fluorescent lipophilic membrane stain. The larvae were found to rotate around the oral–aboral axis, with their surface against the substratum, not favoring a particular side for detecting cues. While clarifying the regions of the larval body important for settlement and metamorphosis in coral planulae, we conclude that significant differences between coral species may be due to differences in the distribution of sensory structures in relation to different planular sizes.

A typical nemertean pilidium larva resembles a hat with ear flaps. But one type, called pilidium recurvatum, looks more like a sock, swimming heel first. This distinctive larva was discovered in 1883 off the coast of Rhode Island and subsequently found in plankton samples from other parts of the world. Despite the long time since discovery, and its significance in discussions of larval evolution, this larva remained unidentified even to the family level. We collected pilidium recurvatum larvae from plankton samples in Coos Bay, OR, and identified them as belonging to the heteronemertean genus Riserius based on juvenile morphology and DNA sequence data. Phylogenetic analysis suggests that two distinct types of pilidium recurvatum from Oregon represent two new species within this currently monotypic genus. We describe the morphology of pilidium recurvatum using confocal microscopy and compare it to that of the typical pilidium, discussing possible implications for larval feeding. We also report our surprising discovery that juveniles of Riserius sp. from Oregon prey on another nemertean, Carcinonemertes errans, an egg predator of Cancer magister (Dungeness crab), a commercially important species. We speculate that the species-level diversity and geographic distribution of Riserius may be much greater than currently appreciated.

The ovaries of aphids belonging to the families Eriosomatidae, Anoeciidae, Drepanosiphidae, Thelaxidae, Aphididae, and Lachnidae were examined at the ultrastructural level. The ovaries of these aphids are composed of several telotrophic ovarioles. The individual ovariole is differentiated into a terminal filament, tropharium, vitellarium, and pedicel (ovariolar stalk). Terminal filaments of all ovarioles join together into the suspensory ligament, which attaches the ovary to the lobe of the fat body. The tropharium houses individual trophocytes and early previtellogenic oocytes termed arrested oocytes. Trophocytes are connected with the central part of the tropharium, the trophic core, by means of broad cytoplasmic processes. One or more oocytes develop in the vitellarium. Oocytes are surrounded by a single layer of follicular cells, which do not diversify into distinct subpopulations. The general organization of the ovaries in oviparous females is similar to that of the ovaries in viviparous females, but there are significant differences in their functioning: (1) in viviparous females, all ovarioles develop, whereas in oviparous females, some of them degenerate; (2) the number of germ cells per ovariole is usually greater in females of the oviparous generation than in females of viviparous generations; (3) in oviparous females, oocytes in the vitellarium develop through three stages (previtellogenesis, vitellogenesis, and choriogenesis), whereas in viviparous females, the development of oocytes stops after previtellogenesis; and (4) in the oocyte cytoplasm of oviparous females, lipid droplets and yolk granules accumulate, whereas in viviparous females, oocytes accrue only lipid droplets. Our results indicate that a large number of germ cells per ovariole represent the ancestral state within aphids. This trait may be helpful in inferring the phylogeny of Aphidoidea.

Evolutionary analysis of mating systems in broadcast-spawning marine animals and plants has focused on sperm- and egg-surface proteins and glycopeptides that mediate reproductive interactions at different stages of gamete recognition. Improved understanding of the ecology and evolution of such interactions depends on extending our knowledge to multiple genes expressed in both sperm and eggs of diverse taxonomic groups with different modes of fertilization. Here, we use readily accessible next-generation sequencing methods and desktop bioinformatics to characterize the repertoire of highly expressed genes in testes and ovaries of the asterinid sea star Patiria miniata, including gene ontology annotations for male- and female-expressed molecules, and descriptions of two genes that encode egg-surface molecules involved in fertilization that have not previously been studied in sea stars. The results are used to contrast expression differences between the testis and ovary, and to develop hypotheses of gamete-specific expression. We also explore differences in ovary gene expression among multiple females from northern and southern populations that show nucleotide differentiation at many non-expressed loci and at a gamete recognition locus.

Externally visible, growing calcitic structures can be marked using fluorochromes. Such marks are useful for field recapture studies in ecology, evolution, and aquaculture as well as for studies on mechanisms of growth and development. We marked 2-month-old sea urchins (Strongylocentrotus droebachiensis) with the fluorochromes calcein, calcein blue, and tetracycline by batch-marking via immersion. Neither growth nor survival was affected by marking. Marks were externally visible on the skeletal plates, demipyramids, and spines of 100% of the marked sea urchins up to 63 d post-marking. After 342 d, marks were still externally visible on 100% of calcein-marked, 98% of calcein blue-marked, and 22% of tetracycline-marked sea urchins. Marks were brightest on calcein-marked and faintest on tetracycline-marked sea urchins, in correspondence to the fluorochrome dose. Growth marks in the aboral oculogenital ring, followed for 333 d, showed that genital plate growth in the hoop direction was greatest adjacent to the anal suture and that both the oculogenital ring and periproct grew less than isometrically. Internal marks (not externally visible) were subsequently seen on 99% of the demipyramids at 342 d post-marking. Such fluorochrome marks on demipyramids have previously been used to measure aboral and oral-end demipyramid growth to allometrically calibrate diametrical growth rates of field sea urchins. We found that although aboral demipyramid marks were always clear, 13% of marks on the oral end were obscured. However, we show that measuring only aboral end growth is sufficient for allometric calibration. In a separate experiment, multiple marks of the above three fluorochromes plus alizarin complexone, administered by injection to larger (12.9–37.1 mm diameter) sea urchins, persisted internally for at least 2 years. Multi-color, internally and externally visible, persistent marks will enhance experimental designs in laboratory, field, and common garden experiments.

Some life history features of the interstitial sea cucumber Rhabdomolgus ruber are described from intertidal specimens collected from the northern coast of Maine. Histological studies suggest that the population consists of hermaphrodites with gametogenesis being initiated in April and reproduction beginning in May and continuing through the summer months. Sexually mature adults possess a single, blind-ended gonadal tubule that functions as an ovotestis by producing both eggs and sperm. The ovotestis wall consists of an outer peritoneum composed of flagellated epithelial cells and muscles; an inner germinal epithelium of germ and somatic cells; and a middle connective tissue (hemal) compartment bounded by the basal laminas of the peritoneum and germinal epithelium. During the reproductive season, the gonadal tubule contains all stages of oocyte development. Vitellogenesis appears to involve the biosynthetic activities of the Golgi complex and rough endoplasmic reticulum. A few specimens had transitional ovotestes with mature sperm in the gonad lumen and asynchronously developing oocytes and a small number of spermatocytes within the germinal epithelium. The mature spermatozoon is an ent-aquasperm with ultrastructural features significantly different from those described from other echinoderm classes including a highly elongated acrosome, a large periacrosomal region between the acrosome and nucleus, numerous unfused mitochondria in the midpiece, and a cytoplasmic sleeve or collar extending posteriorly along the proximal portion of the flagellum. The sperm head reaches 11.5 µm in length (combined midpiece, nucleus, periacrosomal region, acrosome), making it the longest yet reported from the Holothuroidea and among the longest in the Echinodermata. Some elements of this derived morphology could be attributed to fertilization biology, but others may have phylogenetic significance. Spawning behavior was observed in which two individuals appeared to pseudocopulate by intertwining their oral tentacles for several minutes before one of them abruptly secreted an egg mass containing three eggs.