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The wrinkled dove snail (Amphissa columbiana) is a columbellid gastropod common in marine waters along the west coast of North America. This species has long been anecdotally described as an opportunistic scavenger, but little is known about its diet or scavenging behaviors. A. columbiana were observed at subtidal sites within the San Juan Islands, Washington to document associations with potential food items. Laboratory experiments were done to determine what this species eats and how it finds food. In the field, A. columbiana were often found on dead or damaged organisms, frequently in aggregations. In the laboratory, the snails consumed a broad range of dead or damaged invertebrate prey, showing little discrimination. They appear to locate food resources primarily through chemosensory cues, often following conspecific mucus trails and sometimes congregating around actively feeding sea stars. The chemical cues that draw A. columbiana to food act as feeding stimulants; the addition of scent from a damaged animal induced the snails to feed on healthy prey. The ability to sense chemical cues from damaged animals, including those being consumed by feeding sea stars, creates scavenging opportunities other gastropods may be unable to exploit.

Accumulations of green macroalgae (green tides) are becoming increasingly common in many coastal habitats and substances released by these blooms may impact other organisms. In the northeastern Pacific, a dominant contributor to green tides is Ulvaria obscura, an alga that produces dopamine which affects a variety of physiological processes and can trigger metamorphosis in marine invertebrates. Eggs, embryos, and larvae of Pacific oysters (Crassostrea gigas) and sand dollars (Dendraster excentricus) were exposed to U. obscura exudates and dopamine to determine how exposure affects fertilization, development, and morphology. Exposing eggs to these compounds had no significant effect on fertilization of C. gigas and limited impact on D. excentricus, relative to unexposed controls. Early embryos exposed to the compounds developed successfully, but the resulting C. gigas veligers had larger shells and the D. excentricus gastrulae had shorter archenterons. When exposed to dopamine, C. gigas veligers had smaller shells, while larval arms of D. excentricus were significantly shorter relative to unexposed controls. Results indicate that compounds released by U. obscura affect development differently between invertebrate species and among developmental stages. The stage-specific responses likely result from changes in structure and metabolic activity at different life history stages, as well as changes in the localization and function of dopamine and dopamine receptors that occur during larval development. The changes in larval morphology and function induced by compounds released by marine macroalgae could ultimately impact the ability of larvae to feed and survive.

Because planktonic invertebrate larvae may be food-limited, anything that increases feeding and digestive efficiency should increase the chances of larval survival to metamorphosis. As light directly enhances both feeding and digestion in some planktonic heterotrophic protists, we hypothesize that similar processes might occur in the larvae of marine invertebrates. We studied the direct effects of light on feeding and development in sea urchin larvae (Strongylocentrotus droe- bachiensis, S. franciscanus and sand dollar Dendraster excentricus). Larvae were placed in 12:12 h light:dark cycles or in complete darkness and ingestion rates were measured. We monitored larval morphology during the first 2 to 3 wk of development and tested for light-related differences. Short- term changes in light regime had no effect on feeding rates. However, larvae of all 3 species showed longer-term diel feeding patterns with ingestion rates generally higher during daylight hours. These patterns persisted in S. franciscanus larvae even when larvae were held in complete darkness for 3 d. Larvae of D. excentricus exposed to natural light cycles developed longer arms usually associated with food limitation; those held in darkness had significantly shorter arms. The developing juvenile structures (i.e., rudiments) of S. droebachiensis larvae exposed to light were significantly smaller than those of larvae held in continuous darkness, suggesting that light may have negative effects on larval growth and development. Measuring the effects of light on feeding and growth may clarify the behaviors of invertebrate larvae during their critically important planktonic period.

Nutritional provisioning that passes from a mother to her offspring can produce maternal carryover effects. Though the importance of maternal carryover effects on embryos and early juveniles is well established, it is less clear how long the effects persist and whether they can be detected in subsequent life stages of the offspring. Manipulating the amount of food available to a maternal organism is one way to manipulate maternal investment ability and thereby test maternal carryover. We collected adult brooding Leptasterias aequalis from three beaches with varying prey communities in the northern Puget Sound. When broods were released, we measured size and survival of the juveniles under starvation conditions. The maternal sea stars were then assigned to different feeding treatments and their diets were controlled for a full year until they spawned again. We measured size and growth of juveniles released from these second broods. Juvenile L. aequalis from the initial broods showed surprising resistance to starvation with 80% survival after 6 months and some juveniles living a full year with no food. Juvenile survival over time varied significantly among the mothers from the three study beaches, but we were unable to demonstrate a significant difference in the mean month of juvenile death. Juvenile size also varied significantly among mothers from the three study beaches, even when differences in female size by beach were accounted for. Adult female feeding treatments had no effect on the size of juveniles in the second broods. The patterns of juvenile performance mirrored those seen in the first year regardless of feeding treatment. The beach that a female came from seemed to have a stronger effect than a year of diet treatment. When looking at multiple generations of carryover in L. aequalis , it seems that genetic legacies, and possibly full female feeding history, have a greater effect on juvenile quality than a single year of maternal feeding.

Enormous variation exists in the reproductive output of marine invertebrates (e.g., in the numbers of embryos produced, the volumes of embryos, and the energy that they contain). It is not clear why there is such great variability or what the population-level consequences are. We sampled a population of the brooding seastar Leptasterias aequalis (Stimpson, 1862) to collect basic information on brood sizes, embryo volume, and embryo energy content with a goal to better understand the reproductive ecology of this species. We collected brooding females in February and again in April. We measured the size of their broods and sampled the broods to estimate volume and energy content of the embryos. There was great variability in the volume and energy content of embryos produced by individual females and among the embryos in a single female's brood. Larger adults produced larger embryos, which generally had greater energy content and may be of a higher quality. The average energy content of embryos appeared to increase during the brooding period. Larger females produced larger broods but lost a greater proportion of the embryos. The net result is that larger individuals may not produce any more juveniles than smaller individuals, but those that they do produce may be of a higher quality.

Barnacle encrustation negatively influenced every aspect of swimming in the scallop Chlamys hastata measured in this study. Scallops swam significantly longer, travelled further and attained greater elevation once epibiotic barnacles had been removed. Shell morphometry of barnacle-encrusted scallops was similar to shells of unencrusted scallops. Specifically, shell length was positively allometric with shell height and shell mass was negatively allometric. However, adductor muscle mass scaled isometrically to shell height, in contrast to unencrusted scallops. In the laboratory, the drag coefficient (Cd) of barnacle-encrusted scallops decreased after barnacle removal, in contrast to sponge-encrusted scallops in which no decrease in Cd was detected when the sponge was removed from the scallop's valves. Furthermore, scallops swimming with barnacle encrustation required more energy than did unencrusted scallops. Although there was no significant difference in aerobic energy expenditure between swimming barnacle-encrusted and unencrusted scallops, differences in anaerobic energy expenditure were detected. Specifically, barnacle-encrusted scallops required more arginine phosphate than unencrusted scallops to swim to exhaustion although octopine levels were similar. Thus, barnacle encrustation dramatically decreased a scallop's ability to swim, partly by increasing the drag coefficient experienced by the scallop and the energy required for swimming.

The small free-swimming scallops, Chlamys hastata and Chlamys rubida, are frequently encrusted by the sponges Mycale adhaerens and Myxilla incrustans. It is unclear why this association exists. We hypothesized that living on scallop valves increases sponge survival by reducing the effects of sediment accumulation. Scallops were collected to measure correlations between sediment load and encrusting sponge mass. In the laboratory, the survival of sponges on living scallops and empty scallop valves was measured. Time-lapse video was used to quantify spontaneous swimming and clapping of C. hastata. In the field, both scallop size and sponge mass were significantly greater in high turbidity sites. In the laboratory, sponges on empty scallop valves experienced near complete mortality after five weeks. Manually clearing sediments increased survival but did not duplicate the high survival of sponges on living scallops, which regularly swam or clapped their valves.

The effect of sponge encrustation on swimming ability of Chlamys hastata was determined by investigating swimming behaviour, scallop morphometry, and energy expended during swimming with and without commensal epibionts. Scallops swam significantly longer after sponge encrustation was removed from their shells, but no significant differences were detected in swimming elevation or distance. Scallops with sponge encrustation showed no adductor muscle hypertrophy or changes in shell morphometry compared to scallops without encrustation. However, C. hastata did exhibit scaling relationships associated with maximizing swimming efficiency. Specifically, shell width and adductor muscle mass were positively allometric with shell height, while shell mass was negatively allometric with shell height. Scallops increased their energy expenditure (both aerobic and anaerobic) during valve-clapping, but no significant difference was detected between unencrusted (43·0 μmol adenosine triphosphate [ATP] consumed during a two min escape swim) and sponge-encrusted (40·0 μmol ATP) scallops. Scallops in both treatments derived 86% of the energy used for swimming from anaerobic sources. The lack of substantial differences between scallops with and without commensal sponges is partially explained by the observation that even heavy sponge encrustation increases the immersed weight of the scallop by only 5%. The presence of a sponge encrustation does not appear to inhibit swimming by this scallop species.

The ascidian Corella inflata (Chordata, Ascidiacea) is common in many areas of Puget Sound, Washington, USA. However, it occurs only in habitats where it is protected from direct sunlight. Previous experiments with artificial lights showed that UV irradiation kills all life stages of this animal. The effects of natural sunlight exposure (measuring survival of adults, juveniles, larvae, and embryos) were compared. We partitioned the light spectrum to separate the effects of UVB, UVA, and visible light (PAR). Natural sunlight severely damaged C. inflata. Adults and juveniles died after 2-5 d. Exposed embryos failed to develop normally and larvae did not settle. As expected, UVB had significant effects, but pronounced effects were also seen when the animals were exposed to longer wavelengths alone (UVA and PAR). Thus, the distribution of C. inflata may be determined largely by exposure to light. Understanding the basic ecology of this species requires consideration of its vulnerability to sunlight damage and the effects of UVB, UVA, and PAR.

In the coastal waters of Florida (USA) tadpole larvae of the colonial ascidian Ecteinascidia turbinata contain chemicals which make them unpalatable to planktivorous juvenile pinfish Lagodon rhomboides. Experiments demonstrate that the bright organe color of E. turbinata tadpoles is aposematic. Fish that have recently tasted larvae of E. turbinata will not attack the palatable tadpoles of Clavelina oblonga when the latter are dyed organe to resemble larvae of E. turbinata. Tadpoles of E. turbinata that have been mouthed and rejected by fish generally survive to complete a normal metamorphosis. Individual selection explains the evolution of aposematic coloration in E. turbinata better than kin selection. The identity of the defensive chemical is unknown. The unpalatable substance in larvae of E. turbinata is removed by dialysis, indicating that it has a molecular weight less than 14000 d. Larvae are not acidic, nor is the active substance denatured by doiling.

Many potentially predatory species of gastropods, decapods, asteroids, and fishes were tested to determine their responses to Psolus chitonoides Clark. Asteroids, particularly Dermasterias imbricata (Grube), were found to be the only important predators. Psolus chitonoides was not found in guts of any field-collected fishes, though other sea cucumbers were. Psolus chitonoides had the highest saponin content of four species of Greater Puget Sound holothurians tested. Homogenates of P. chitonoides were highly unpalatable to the tidepool sculpin, Oligocottus maculosus Girard and tissues were toxic when force-fed to O. maculosus. Toxicity of Psolus chitonoides tissue was due to the high saponin content whereas unpalatability appears to be unrelated to the saponins. Toxicity of saponins from Puget Sound holothurians to Oligocottus maculosus depends on whether the toxin is respired or ingested.

The direct developmental mode and sedentary habit of Leptosynapta clarki (Heding), an infaunal, brooding holothuroid, suggest that this species has limited dispersal capabilities. Using starch gel electrophoresis, we estimated allele frequencies at two polymorphic enzyme loci in three populations to look for consequences of limited dispersal on genetic structure of populations. Genetic composition within populations was characterized by linkage equilibrium and heterozygote frequencies which equalled or exceeded Hardy-Weinberg expectations, indicating that inbreeding does not occur and self-fertilization is not a common reproductive mode in this species. Comparisons among populations separated by 11–24 km showed significant differences in allele frequencies at both loci, indicating that populations are genetically differentiated. These differences are probably due to genetic drift or local adaptation occurring in the absence of high levels of gene flow.