Fertilization and early development are usually the most vulnerable stages in the life of marine animals, and the biological processes during this period are highly sensitive to the environment. In nature, sea urchin gametes are shed in seawater, where they undergo external fertilization and embryonic development. In a laboratory, it is possible to follow the exact morphological and biochemical changes

The timing of reproduction is often governed by environmental variables, such as temperature or rainfall. Understanding how environmental variables affect mating dynamics is necessary to predict how systems and populations may adapt to changing environmental conditions and is crucial for management of threatened species. The American horseshoe crab (Limulus polyphemus) ranges from the Yucatan to Maine

The intertidal isopod Dynoides dentisinus is a sexually dimorphic species; males are much larger than females and have a large, horn-like pleonal process (hereafter referred to as a “horn”) and large, posteriorly extended uropods. Here, we investigated the function of these structures with regard to their mating system. Behavioral interactions were observed between a male occupying a small tube (resident)

Oxygen limitation has been proposed as one of the key factors that limits body size at high temperatures (the oxygen-temperature hypothesis). Geographic patterns in body size are thought to be driven in part by the effects of temperature on oxygen supply and demand, particularly when the increased oxygen demand of tissues at higher temperatures outpaces the ability of large organisms to supply internal

Diplopteraster verrucosus is a sea star that incubates its offspring in nidamental chambers. The offspring rely exclusively on maternally provided nutrition. The retention of the embryonic stages allows the allocation of nutritional supplies from the female to the brooded juveniles during the brooding period. The main objectives of this study are, first, to quantify the reproductive investment of D

Changes in temperature alter the viscosity of fluids, which impacts the force needed to move and the diffusion rates of gases. This is particularly salient for organisms that operate at mid to low Reynolds numbers. In this study, we investigated the independent effects of changes in temperature and viscosity on oxygen consumption rates of two coastal copepods (Acartia tonsa and Parvocalanus crassirostris)

The Biological Bulletin, Volume 238, Issue 3, Page 214-216, June 2020.

Of the more than 150 ctenophore species, the oceanic ctenophore Eurhamphaea vexilligera is notable for its bright orange-yellow ink, secreted from numerous small vesicles that line its substomodeal comb rows. To date, in situ observations by scuba divers have proved the most fruitful method of observing these animals’ natural behavior. We present the results of one such contemporary scuba-based observation

The basket star Gorgonocephalus eucnemis is an aerobic organism highly dependent on dissolved oxygen in surrounding waters. Previous observations on the anatomy of Gorgonocephalus state that five pairs of ossicles (the radial shields and genital plates) regulate the position of the roof of the body disc and are responsible for flushing seawater into and out of the bursae, though this seems never to

Because in vivo nematocyst discharge requires extracellular Ca2+, Ca2+ channels have been suspected to be involved; but their identity and role have not been revealed. The majority of nematocysts that discharge from sea anemone tentacles are under the control of sensitizing chemoreceptors for N-acetylated sugars (e.g., N-acetylneuraminic acid). Activated chemoreceptors predispose contact-sensitive

Phronimid amphipods are oceanic crustaceans associated with gelatinous zooplankters. Their host organisms belong mainly to two taxonomic groups: tunicates (salps or pyrosomes; subphylum Tunicata) and siphonophores (Cnidaria). After these amphipods devour the inner tissues of their hosts, they display the unique behavior of modifying their hosts into hollow barrel-shaped shelters, which are then utilized

Sacoglossans, or “sap-sucking” sea slugs, are primarily algivorous, with many taxa exhibiting kleptoplasty, the feeding and retaining of photosynthetically active chloroplasts from algae. The Plakobranchus species complex exhibits some of the longest kleptoplast retention and survival times under starvation conditions, but the contributions of these kleptoplasts to their survival and overall fitness

Ecosystem responses to invasion are strongly influenced by interactions between invaders and native species. If native species provide biotic resistance by consuming or competing with an invader, the invasion may be slowed, and/or invasive populations may be limited. If local herbivores recognize an invasive plant as being similar to native species, they may graze it more readily. Biotic resistance

The Biological Bulletin, Volume 238, Issue 3, June 2020.

The Biological Bulletin, Volume 238, Issue 3, June 2020.

This study presents novel findings on the dynamics of growing oocytes in the ovary of the medaka fish, Oryzias latipes. In the ovary of mature females, all follicles are anchored tightly to the abdominal ovarian rete via fibrous follicular stalks on the follicle surface. The follicular stalks lie at the end of the follicle opposite the site of its attachment to the ovarian wall. Various lengths of

Marine organisms that rely on environmental cues for reproduction are likely to experience shifts in reproductive phenology and output due to global climate change. To assess the role that the environment may play in the reproductive timing for temperate sponges, this study examined sexual and asexual reproduction in New Zealand sponge species (Tethya bergquistae and the Tethya burtoni complex) and

Daylength is a major environmental condition that varies seasonally and predictably along a latitudinal cline, where higher latitudes exhibit greater ranges in total daylengths. Generally, the circadian clock acts as a network of genes whose expression dynamics are known to control daily rhythms in response to daylength, and it enables the control of many physiological processes such as growth and

Red coloration is a widely distributed phenotype among animals, yet the pigmentary and genetic bases for this phenotype have been described in relatively few taxa. Here we show that the Hawaiian endemic anchialine shrimp Halocaridina rubra is red because of the accumulation of astaxanthin. Laboratory colonies of phylogenetically distinct lineages of H. rubra have colony-specific amounts of astaxanthin

Spiny dogfish (Squalus acanthias) and smoothhound (Mustelus canis) sharks in the northwest Atlantic undergo seasonal migrations driven by changes in water temperature. However, the recognized thermal habitats of these regional populations are poorly described. Here, we report the thermal range, catch frequency with bottom temperature, and catch frequency with time of year for both shark species in

Animals that reside, reproduce, and develop in nearshore habitats are often exposed to strong fluctuations in abiotic conditions, including temperature and salinity. We studied the developmental response of the sand dollar Dendraster excentricus to increased temperature and reduced salinity at levels comparable to those induced by summer freshwater input into the San Juan Archipelago, Washington. We

In the Florida Keys, queen conchs (Lobatus gigas) occur in two spatially distinct regions: nearshore in habitats immediately adjacent to the shoreline and offshore in habitats along the reef tract south of the islands. Our previous research demonstrated that adult conchs nearshore are not reproductively active, showing deficiencies in their gonadal condition compared to their offshore counterparts

Failed invasions can be a key component for understanding and controlling introduced populations because understanding mechanisms behind failures can improve effective controls. In 2000, the non-native sea anemone Sagartia elegans was first found in Salem, Massachusetts, and it recolonized each summer. No individuals of S. elegans have been found after 2010, despite intensive search efforts. A mismatch

Confocal laser scanning microscopy was used to study the myoanatomy of the lophophore of three phoronids with different types of lophophore: Phoronis ijimai, Phoronis australis, and Phoronopsis harmeri. A four-part ground plan of the lophophoral musculature was detected in all three species and was previously reported for Phoronis ovalis. The ground plan includes (i) a circular muscle, (ii) longitudinal

An unequal cleavage gives rise to a dedicated population of larval skeletogenic cells in sea urchins. The timing of this unequal cleavage, associated localization of key lineage markers, and loss of this lineage when embryos are treated with cleavage-equalizing reagents have all suggested that the asymmetry of the daughter cells is causal to the specification of this cell lineage. However, the mechanism

Pyramidellids are tiny ectoparasitic gastropods with highly derived feeding structures for piercing and sucking. We attempted to resolve homology controversies about unique pyramidellid feeding structures by examining foregut development through larval and metamorphic stages, using sections for light and electron microscopy. We anticipated that, like many marine invertebrate larvae, post-metamorphic

An in-depth look at the basic aspects of dormancy in cyclic parthenogenetic organisms is now possible thanks to research efforts conducted over the past two decades with rotifer dormant embryos. In this review, we assemble and compose the current knowledge on four central themes: (1) distribution of dormancy in animals, with an overview on the phylogenetic distribution of embryo dormancy in metazoans

Long-lasting embryonic dormancy in invertebrates defies our understanding of what constitutes life because, for example, eggs of some copepods can delay hatching for decades or even centuries. Copepods, often millimeter-sized crustaceans, are some of the most numerous multicellular organisms on earth and are key organisms in most aquatic food webs. Some important free-living marine and estuarine species

Calanus finmarchicus and Calanus glacialis are keystone zooplankton species in North Atlantic and Arctic marine ecosystems because they form a link in the trophic transfer of nutritious lipids from phytoplankton to predators on higher trophic levels. These calanoid copepods spend several months of the year in deep waters in a dormant state called diapause, after which they emerge in surface waters

Dormancy is evolutionarily widespread and can take many forms, including diapause, dauer formation, estivation, and hibernation. Each type of dormancy is characterized by distinct features; but accumulating evidence suggests that each is regulated by some common processes, often referred to as a common "toolkit" of regulatory mechanisms, that likely include noncoding RNAs that regulate gene expression

Dormancy and diapause are key adaptations in many organisms, enabling survival of temporarily or seasonally unsuitable environmental conditions. In this review, we examine how our understanding of programmed developmental and metabolic arrest during diapause intersects with the increasing body of knowledge about animal co-development and co-evolution with microorganisms. Host-microbe interactions are

Diapause at depth is considered an integral part of the life cycle of Calanus copepods, but few studies have focused on the Arctic species Calanus glacialis and Calanus hyperboreus. By analyzing a large set of pan-arctic observational data compiled from multiple sources, we show that Arctic Calanus has a broad depth distribution in winter, indicating that diapause at depth is a facultative strategy

Despite the fact that Hydra has been studied for more than 200 years, we know surprisingly little about its life history. We show that Hydra vulgaris embryos hatch sporadically over a period ranging from a few days to nine months. We also report, for what seems to be the first time, the presence of Hydra in a vernal pool. Phylogenetic analysis and sexual crossing show that this Hydra is a member of

Post-embryonic diapause in copepods is an adaptation that allows species in the copepod family Calanidae to thrive in high-latitude environments by transforming a short spring phytoplankton bloom into large numbers of lipid-rich individuals capable of surviving a long period of starvation. The copepods, with their high-energy lipid reservoirs, are a critical food source for higher trophic levels, making

The pteropod mollusc Clione limacina is a feeding specialist, preying on shelled pteropods of the genus Limacina. Specialized prey-capture structures, called buccal cones, are hydraulically everted from within the mouth to capture the prey. Once captured, the prey is manipulated so the shell opening is over the mouth of Clione. Analyses of high-speed cine sequences of prey capture suggest that the

In this quantitative proteomics study we determined the variety and relative abundance of toxins present in enriched preparations of two nematocyst types isolated from the primary tentacles of the adult medusa stage of the hydrozoan Olindias sambaquiensis. The two nematocyst types were microbasic mastigophores and microbasic euryteles, and these were recovered from the macerated tentacle tissues by

Marine invertebrate larvae have often been reared in artificial rather than natural seawater, either for convenience or to avoid potentially confounding effects of unknown contaminants. This study sought to determine the impact of artificial seawater on various aspects of development for three marine invertebrate species. We examined the impact of Instant Ocean on growth, survival, and fecundity of

Metabolic activation can have a profound impact, for instance, by more than compensating for the lower resting metabolic rates of large organisms compared to smaller ones. In some animals, activity can easily be judged by the rate of muscle-driven movement. In sessile organisms, however, judging activity is less straightforward, although feeding often results in metabolic activation. Two colonial cnidarians

Anthropogenic activities and climate change have resulted in an increase of hypoxic conditions in nearshore ecosystems worldwide. Depending on the persistence of a hypoxic event, the survival of aquatic animals can be compromised. Temperate fish exposed to hypoxia display a reduction in the probability of eliciting startle responses thought to be important for escape from predation. Here we examine

The pen, or gladius, of the squid is an internalized shell. It serves as a site of attachment for important muscle groups and as a protective barrier for the visceral organs. The pen's durability and flexibility are derived from its unique composition of chitin and protein. We report the characterization of the structure, development, and composition of pens from Doryteuthis pealeii. The nanofibrils

Sporadic fluctuations in food availability may affect larval biology and post-metamorphic development in many marine invertebrates. In an experimental study in the laboratory, we investigated whether different regimes (1, 3, and 5 days) of initial starvation or feeding affect the survival and duration of the last planktotrophic larval stage (i.e., megalopa) of the neotropical mangrove fiddler crab

The barnacle Balanus glandula is a broadly distributed species in the temperate northeastern Pacific that is notable for a robust genetic cline between about 36° and 40° N latitude. Prior work established the evolutionary origins of this pattern and proposed that it is maintained by environmental selection. In recent years, "climate velocity" studies in marine habitats have shown dramatic distributional

Salinity is one of the most crucial environmental factors that structures biogeographic boundaries of aquatic organisms, affecting distribution, abundance, and behavior. However, the association between behavior and gene regulation underlying acclimation to changes in salinity remains poorly understood. In this study, we investigated the effects of salinity stress on behavior (movement distance) and

Horseshoe crabs are harvested by the biomedical industry in order to create Limulus amebocyte lysate to test medical devices and pharmaceutical drugs for endotoxins. Most previous studies on the impacts of the biomedical bleeding process on horseshoe crabs have focused on mortality rates and sublethal impacts in the laboratory. In this study, we investigated the effects of the bleeding process on the

Two juvenile specimens of a new species of Oreaster were collected at Parque Nacional Arrecife Alacranes and Triángulos Oeste in the southern Gulf of Mexico. DNA of mitochondrial loci identifies them as members of the same clade as cloning larvae of Oreaster found abundantly in waters of the Florida Current-Gulf Stream system, and distinct from Oreaster clavatus and Oreaster reticulatus, the two known

Ocean acidification poses a significant threat to calcifying invertebrates by negatively influencing shell deposition and growth. An organism's performance under ocean acidification is not determined by the susceptibility of one single life-history stage, nor is it solely controlled by the direct physical consequences of ocean acidification. Shell development by one life-history stage is sometimes

In species with complex life cycles, early developmental stages are often less thermally tolerant than adults, suggesting that they are key to predicting organismal response to environmental warming. Here we document the optimal and lethal temperatures of larval sea urchins, and we use those to calculate the warming tolerance and the thermal safety margin of early larval stages of seven tropical species

Acoustic communication is vital across many taxa for mating behavior, defense, and social interactions. Male oyster toadfish, Opsanus tau, produce courtship calls, or "boatwhistles," characterized by an initial broadband segment (30-50 ms) and a longer tone-like second part (200-650 ms) during mating season. Male calls were monitored continuously with an in situ SoundTrap hydrophone that was deployed

Sacoglossan sea slugs feed by suctorially consuming siphonaceous green algae. Most sacoglossan species are feeding specialists, but the Caribbean coral reef-dwelling Elysia crispata is polyphagous and sequesters chloroplasts from multiple algal species into cells lining its digestive diverticulum for use in photosynthesis. We have used sequences of the chloroplast-encoded rbcL gene to compare the chloroplast

The bilaterally symmetrical, feeding larval stage is an ancestral condition in echinoderms. However, many echinoderms have evolved abbreviated development and form a pentamerous juvenile without a feeding larva. Abbreviated development with a non-feeding vitellaria larva is found in five families of brittle stars, but very little is known about this type of development. In this study, the external

Sea urchins can detect and respond to light, and many species of sea urchins are negatively phototaxic. Light detection is hypothesized to occur via photoreceptors located on sea urchin tube feet, and opsins have been detected in tube feet, spines, and the test. However, the molecular mechanisms underlying light detection are, for the most part, unknown. Individual tube feet disc cells were isolated

Molluscan veliger larvae and some annelid larvae capture particulate food between a preoral prototrochal band of long cilia that create a current for both swimming and feeding and a postoral metatrochal band of shorter cilia that beat toward the prototroch. Larvae encountering satiating or noxious particles must somehow swim without capturing particles or else reject large numbers of captured particles

The neurotransmitter gamma-aminobutyric acid (GABA) is widely distributed in the mammalian central nervous system, where it acts as a major mediator of synaptic inhibition. GABA also serves as a neurotransmitter in a range of invertebrate phyla, including arthropods, echinoderms, annelids, nematodes, and platyhelminthes. This article reviews evidence supporting the neurotransmitter role of GABA in

Alternative male phenotypes exist in many species and impact mating system dynamics, population genetics, and mechanisms of natural and sexual selection that operate within a population. We report on the discovery of a cryptic male phenotype in the mangrove rivulus fish (Kryptolebias marmoratus), one of only two self-fertilizing hermaphroditic vertebrates. In this androdiecious species, males are infrequent