Gelatinous zooplankton play important roles in marine ecosystems and at times can have significant impacts on human activities. Many scyphozoans have enigmatic life cycles and the specific habitat for benthic life history stages is unknown. This is especially true for many of the large surface-cruising scyphomedusae of the northeast Pacific Ocean. Phacellophora camtschatica belongs to the family Ulmaridae and is known to have scyphistomae in the life history. However, the life cycle of P. camtschatica has not been formally described. Here the life cycle of members of P. camtschatica is described based on laboratory observations and compared with early life history stages in the scyphomedusa Aurelia labiata.

The functional morphology and the topographic distribution of tissues in the reproductive system of specimens of Dugesia leporii, an endemic Sardinian free-living planarian, are investigated. Data are provided on the nature of epithelial and glandular secretions, spermatophores, and cocoons by histochemistry, light microscopy, and scanning electron microscopy. All secreting epithelial cells produce strongly acidic sulfated glycoproteins. Glandular cells secrete strongly acidic sulfated glycoproteins or keratohyalin-like material in the penis bulb, and prekeratin-like material in atrial glands. Secretions of the bursa copulatrix may be involved in the activation of sperm while material produced by the bursa canal and oviducts probably serves to propel spermatophores or sperm and eggs. Mucous secretion of the seminal vesicle may serve to dilute and activate sperm before copulation. The viscous secrete of the ejaculatory duct and vasa deferentia may play a protective role to maintain sperm viability. Materials produced by the penis papilla and atrium probably lubricate the epithelial surface. The bilayered wall of spermatophore made of keratohyalin-like material and strongly acidic sulfated glycoproteins is produced by two gland types of the penis bulb. The bilayered shell of cocoon made of prekeratin-like and keratohyalin-like materials is secreted by both atrial glands and vitelline cells. The cocoon stalk is made of keratohyalin-like material produced by cement glands. Shell glands, producing GAG, are not involved in cocoon formation, but they may be implicated in the dilution and activation of seminal material to favor sperm movement toward the oviducts.

The present experiments are part of a larger study designed to investigate the influence of husbandry parameters on the life history of the ramshorn snail, Marisa cornuarietis, in order to identify suitable husbandry conditions for maintaining multi-generation populations in the laboratory for use in ecotoxicological testing. In this paper we focus on the effects of a combination of food types and feeding frequencies (i.e., the frequency with which the snails were offered food) on juvenile growth and survival at different temperatures. Offspring produced in the laboratory by wild specimens of M. cornuarietis, from Puerto Rico, were used to test the effects of three types of food (lettuce, alginate with fish food, alginate with snail mix) fed at three frequencies (given ad libitum on 4/4, 2/4, or 1/4 d) on juvenile survival and growth. The 4-d feeding regimens were repeated four times, giving a total of 16 d for the experiments. The experiments were conducted at two temperatures (22° and 25°C) under a 12 h light:12 h dark photoperiod. Juvenile growth rates increased with increasing feeding frequency for all food types. The most rapid growth rates occurred in the high-frequency lettuce treatments and the slowest growth rates in the low-frequency lettuce and alginate with snail mix treatments. Juvenile snails grew faster at 25° than at 22°C, and mortality was about twice as high at the lower temperature. Growth rates were used to provide a rough estimate of time to maturity, which was determined to take about twice as long at 22° than at 25°C. The results showed that lettuce is the best food if supplied in abundance, but effects on growth are very dependent on feeding frequency and temperature. We conclude that 25°C is a more appropriate temperature for maintaining populations than 22°C, that lettuce provides a suitable food source, and that food should be supplied continuously for husbandry and toxicity testing of populations of M. cornuarietis.

The ultrastructure of the male gonad of Eulimnadia texana (Branchiopoda, Spinicaudata) has been observed for the first time to investigate the sexuality of a well-studied case of androdioecy in the animal kingdom. The male gonad is a double structure located in the hemocoel throughout the entire body length on each side of the midgut. Male gametes originate from the wall and mature centripetally toward the lumen; the proliferative activity is very high and continuous and therefore the mature gonad is full of numerous germ cells. Inside the lumen several degenerative stages are found mixed with sperm cells and spermatids, the latter two being not easily distinguishable because of the slight differences between them. The evolutionary meaning of the degenerative process in E. texana male gametes is difficult to explain, and we propose some hypotheses about its possible role or cause in the studied population: (a) to help build spermatophores, (b) to act as a trophic component for viable sperm, (c) as a manifestation of inbreeding depression, and/or (d) to regulate the number of sperm cells.

Protease activity in the midgut gland, gastric chamber, and gastric juice from the crabs Callinectes bellicosus and Callinectes arcuatus was characterized by several methods, confirming that the composition of digestive proteases is the same in the gastric juice and the midgut gland. Gastric juice was suitable for the identification and characterization of the proteinases trypsin and chymotrypsin. Such enzymes were presented as isotrypsins and isochymotrypsins. Proteinase composition evaluated by SDS-PAGE and substrate-SDS-PAGE showed differences between species, but not between gender. Proteinases were thermostable at 40°–50°C for 1 h and showed maximum activity at pH 6–8, making the use of digestive proteinases for evaluations of protein digestibility by the pHstat method possible. We propose using gastric juice as a source of digestive enzymes for in vitro studies of enzymes in digestibility assays and characterization procedures.

Xyloplax janetae n. sp. is described from the northeast Pacific Ocean. This is the third species recognized for the monogeneric Concentricycloidea. Skeletal structures are elaborated by scanning electron microscopy and compared with those of Xyloplax medusiformis from New Zealand and Xyloplax turnerae from the Bahamas. Critical-point-dried specimens show fibrous connective tissue emerging from openings on the abactinal surface, on the abactinal spine bases, and at broken cross sections of the adambulacral spines. Knob-like structures emerging through the stereom openings of the abactinal spine base are also observed. Tube feet have round, swollen knobs and show few striations relative to other asteroids. Cosmopolitan bathyal–abyssal echinoderm species tend to exhibit few morphological differences over broad geographic ranges; this generalization is true of Xyloplax. The Concentricycloidea is proposed as an infraclass within the Asteroidea, as the sister branch to the Neoasteroidea (the crown-group asteroids) within the subclass Ambuloasteroidea. The hypothesis presented is compatible with recent phylogenetic data supporting affinities between Xyloplax and the Asteroidea. Characters plesiomorphic in basal neoasteroids are consistent with a sister-group relationship to concentricycloids. Actinal plate presence, an important synapomorphy for the Neoasteroidea, is absent from concentricycloids. The substantial morphological departure of Xyloplax is considered to be associated with the post-Paleozoic diversification of crown-group asteroids rather than from modification of an established and conservative morphology.

The highly modified development of the brittle star Amphiodia occidentalis is described from post-fertilization to the juvenile stage. Fertilized eggs are negatively buoyant, ∼190 µm in diameter, surrounded by a thick hyaline layer and a tough fertilization envelope. After gastrulation, embryos flatten into a bilaterally symmetrical disk with a U-shaped ridge surrounding an indented stomodeum on the oral surface. Internally, a ring of ∼22 calcitic ossicles grows at the edge of the disk. Vestigial ophiopluteal structures such as a ciliated band, paired larval spicules, or larval arms are not expressed during development. Although the fertilization envelope disintegrates on day 3, developmental stages remain immotile for five more days until they move with podia. At hatching, five hydrocoelic lobes are evident on the left side of the post-gastrula, and these migrate clockwise around the stomodeum, establishing pentamerous radial symmetry. Central and radial plates originate on the right side and migrate to a dorsocentral location as pentamerous symmetry is established. Development of the juvenile oral skeletal frame follows closely that described by Hendler (1978) for Amphioplus abditus except that A. occidentalis did not form buccal scales. The juvenile mouth opened by day 12. Fifty-five days after fertilization, juveniles had not added their first arm segments, although the first lateral arm plates had appeared. Developmental stages identical to those described here have been found in plankton tows taken in Oregon usually after storms that bring high waves. The unusual development of this species probably occurs in both benthic and pelagic environments.

The localization of vitellogenin (Vg) remains untested in amphioxus. Western blotting analysis showed that mouse anti-amphioxus Vg sera cross-reacted with the crude extracts of the hepatic diverticulum and ovary, and humoral fluids, including blood and coelomic fluid, from specimens of Branchiostoma belcheri. Similarly, immunohistochemical staining also revealed that Vg is localized in the hepatic diverticulum, sub-intestinal vessels, and ovary in amphioxus. The hepatic diverticulum of amphioxus, like the vertebrate liver, synthesizes Vg, suggesting that amphioxus hepatic diverticulum is functionally equivalent to the vertebrate liver in respect of the synthesis of this compound. This agrees with the idea that amphioxus hepatic diverticulum is the precursor of vertebrate liver.