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Showing papers in "The Biological Bulletin in 1977"


Journal ArticleDOI
TL;DR: A quantitative sampling survey of the benthic macrofauna inhabiting the intertidal sand and mud flats of Barnstable Harbor, Massachusetts, was conducted to describe general community structure and examine temporal changes in species composition.
Abstract: 1. A quantitative sampling survey of the benthic macrofauna inhabiting the intertidal sand and mud flats of Barnstable Harbor, Massachusetts, was conducted to describe general community structure and examine temporal changes in species composition.2. Classification analysis delimited coarse and fine sand, mud, muddy-sand, and gravel-mud benthic species associations. The 32 species used in the inverse classification analysis were partitioned into 10 species groups, reflecting spatial distributional patterns. Many of the species were both dominant and ubiquitous, masking discrete species groupings.3. The majority of macrobenthos at Barnstable Harbor were deposit-feeders which comprised more than 90% of all organisms sampled. The deposit-feeders normally dominate mud and muddy-sand sediments. Suspension-feeders were most abundant in fine sands. The relationship of sedimentary parameters affecting the distribution of both trophic groups proposed by Sanders is generally supported.4. While no significant change...

124 citations


Journal ArticleDOI
TL;DR: Catch tentacles, found near the mouth in sonie individuals of the sea anemone Metridiunt senile, are more opaque than the regular tentacles and conspicuously larger and are now known to occur in at least some species in six families of acontiate aneniones.
Abstract: Catch tentacles, found near the mouth in sonie individuals of the sea anemone Metridiii;n senile, are more opaque than the regular tentacles and conspicuously larger. In anemones about 6 cm in expande(l column height, representative di niensions of the regular tentacles are 0.5 x 7.0 mm, while noninflated catch tentacles measure al)out 3.0 x 20.0 miiiii. Catch tentacles are capable of expanding to several times their resting length and 1)readth, reaching diniensions of 5.0 x 120.0 nnu. When thus expanded, a catch tentacle repeatedly extends and retracts, touching its tip to the substratuni. These niovements were first mentioned by Gosse (1860) in several British anemones. Carlgren ( 1929) named the large, inflatable tentacles Fangtentakeln and showed theni to have a different cnidom from the other tentacles of the anemone in the species Diadutnene cincta, D. neozelanica, and D. kameruni ensis. Catch tentacles are now known to occur in at least some species in six families of acontiate aneniones : Diadumenidae, Sagartiidae, Metridiidae, Isophel liidae, Sagartiomorphidae, and Haliplanellidae (\Villiams, 1975). The catch tentacles in speciniens of Metridiunt senile from the central California coast were described l)y Hand (1955) . He reported that specimens with catch tentacles formed less than one per cent of the intertidal populations, did not occur as isolated individuals, and showed no obvious pattern in their distribution. He found the catch tentacles to have a strikingly different cnidom than the regular tentacles. The main thrust of Hand's work was taxononiic, and the few observa tions he made on the activities of catch tentacles suggested they might aid in feeding. \Villianis ( 1975 ) , in studies on Ilaliplanella luciac an(l Diaduinene cincta, found that food and other materials did not adhere to the catch tentacles and that the tentacles were not brought to the niouth. \Villianis cited ol)servations of P. R. G. Tranter of the Plyniouth Marine Laboratory that in the anemones Cereus pedun culatus, Sagartia clegans and S. trog1od@'tes, the catch tentacles were used offensively against menibers of their own sl)ecies froni (lifferemit localities and against other species. \Vhen the tip of an expanded catch tentacle contacted another anemone, it adhered to it ; later the catch tentacle formed a constriction and broke here, leaving its tip attached to the victim. The catch tentacles of these species did not adhere to food. Williams ( 1975, p. 244) further noted that “?�Metridiunt senile and Dia dumenc cincta, although possessing catch tentacles, were not observed exhibiting aggressive behavior by Tranter.” Metridium senile reproduces asexually by pedal laceration (Stephenson, 1935), thus forniing clones of a few to niatiy hundreds of individuals. Cloneniates are

111 citations


Journal ArticleDOI
TL;DR: Teniperature-induced shifts in oxygen uptake rates for the aquatic respiration of six species of littoral and sublittoral snails are reported and the principal patterns of their distributional ecology including intertidal vertical zonation are determined.
Abstract: All larger intertidal animals are alternately aerial and aquatic in habit. The majority of littoral molluscs (surprisingly including bivalves as well as gastropods) are adapted for respiration both as air-breathers and by aquatic ventilation of ctenidia or other “?�gill” structures. Temperature relations of aquatic respiration in one of the most common littoral snails, Littorina littorea have been extensively investigated ( Newell, 1969, 1973 ; Newell and Pye, 1970a, b, 1971a, b ; Pye and Newell, 1973 ; Newell and Roy, 1973) , and the occurrence of some degree of regulation in “?�standard metabolism” has been established for that species (Newell and Pye, 1970b ; Pye and Newell, 1973). Comparative studies on congeneric and other related intertidal snails are less extensive ( Sandison, 1966, 1967; Toulmond, 1967a, b). The present report deals with teniperature-induced shifts in oxygen uptake rates for the aquatic respiration of six (and the aerial respiration of four) species of littoral and sublittoral snails. Parallel studies (McMahon and Russell-Hunter, 1974, 1977) on responses to low oxygen stress revealed considerable interspecific differences, but these were less related to vertical zonation on seashores than to microenvironmental factors and to the physiological adaptations of each individual species. With interspecific (and even with infra specific) differences in temperature relations, we are soniewhat more directly con cerned with degrees of aerial exposure and hence with the principal patterns of their distributional ecology including intertidal vertical zonation. Using oxygen electrodes, respiration rates in sea water over a range of natural temperatures were deterniined for Acmaea testudinalis, Mitrella lunata, Lacuna vincta, Littorina obtusata, L. littorea, and L. saxatilis. Corresponding aerial respiration rates were determined for Acmaea and for the three Littorina spp. Early results in these investigations were reported in two preliminary abstracts (McMahon and Russell-Hunter, 1973; Russell-Hunter and McMahon, 1974).

107 citations


Journal ArticleDOI
TL;DR: This study revealed a general trend in the solution of the problems of aerial respiration in several species of amphibious crabs that inhabit marine, estuarine and fresh water.
Abstract: Adaptive responses to different environnients can be functional, structural, be hiavioral or a combination of these. The exposure to different environments can be (lime to changes iii environmental factors or due to the invasion of new habitats l)y a progressive migration of organisms. Invasion of the land has required a numitber of such adaptations in amphibious crabs (Bliss, 1968), foremost amiiong these beimigadaptations connected with respi ratory mechani sni s. ConiparisomiS be tweemi aquatic amid terrestrial crabs have shown that the latter have fewer gills ( Pearse, I 929, 1950) amid reduced gill surface per unit weight (Gray, 1957 ; Bliss, 1963). Also, the gills of terrestrial crabs have become highly scierotized on the edges, presumably to keep themii erect and functional in air ( Harms, 1932) . A conmiectiomi has often been mentioned betweemi the globose carapace of Gecarcinidae, Potamonidae, Pseudothelphusidae and Trichodactyhidae and their ability for aerial respiration. It has been suggested that, durimig the evolution towards a terrestrial habitat, the reduction of gills and gill area is compensated by an increasingly more important role in respiration played by the thin epithehial nienibrane that limies the branchial chamiibers (Carter, 1931; Edney, 1960). The hinimigof the gill chamber has been referred to by many authors as the “?�lung” of land crabs. Indeed, some indications of this “?�lung” exist in the vascularized epithelium of the branchial lining in Uca (Jobert, 1876) and Cardisonza and in the tufts arising from the branchial lining in species of Ocypode, Coenobita amid Birgus (Borradaile, 1903; Harnis, 1932). Of the 4,500 species of brachyuran crabs so far known, many which live in intertidal zones camiwithstand various degrees of exposure to air. However, true amphihiotms life is restricted to a few terrestrial and freshwater forms, niost of thieni belonging to the families Grapsidae, Gercarcinidae, Ocypodidae, Potamonidae, Trychodactylidae, Pseudothelphusidae, and Myctyridae (Bliss, 1968). In the present study, evidence is presemited omithe respiratory fumiction of the himiimig of the branchial chamber in several semiterrestrial brachyuran species from niarine, estuarine, and freshwater habitats. In the course of the present study, seven brachyuran species belonging to four families were used for estimates of branchial chamber volume, observations of the chamber's shape, and examination of the structure of the lining which covers the chamber. The sites of collection varied from the suprahittoral zone of sandy beaches to the mountains of tropical forest and the llanos (savanna-like forest).

102 citations


Journal ArticleDOI
TL;DR: Genetic and the concomitant physiological uniformity explain the well-known tendency for local populations of Haliplanella to disappear suddenly and illustrate a common outcome of the founder effect.
Abstract: Populations of Haliplanella luciae on the Atlantic coast of North America typically are composed of one or a few strictly asexual clones. The lack of genetic variability in one local population, that at Blue Hill Falls, Maine, is reflected in the population's response to extremes of temperature and salinity. As the limits of tolerance are approached, there is an abrupt and epidemic incidence of mortality, rather than a gradual one. Genetic and the concomitant physiological uniformity explain the well-known tendency for local populations of Haliplanella to disappear suddenly and illustrate a common outcome of the founder effect.The success of Haliplanella as a colonizer is due to its extreme hardiness toward physical environmental factors and to its prolific asexual nature. Asexual reproduction by longitudinal fission and by pedal laceration not only provides a means of rapid colonization of a new habitat, but also a means of producing multiple copies of genotypes that have proved to be successful under lo...

91 citations


Journal ArticleDOI
TL;DR: During a six-year period, several thousand intertidal snails, Thais lamellosa and T. emarginata, were given individually numbered tags and times of death were noted, showing changes in the hermit crab population were highly correlated with shell availability.
Abstract: During a six-year period, several thousand intertidal snails, Thais lamellosa and T. emarginata, were given individually numbered tags and times of death were noted. These snails provided most of the shells used by intertidal hermit crabs (primarily Pagurus granosimanus). Therefore changes in the hermit crab population can be related to shell availability. The crab population increased greatly during 1969, and then declined steadily until the end of the study (1973). Changes in the crab population were highly correlated with shell availability. This hermit crab population will remain constant in size if 0.8 shells become available for each crab each month.

83 citations


Journal ArticleDOI
TL;DR: An increase in the rate of antennule flicking and gill bailing upon presentation of sea water solutions of a freeze-dried clam extract indicated detection of sapid substances by the blue crab, Callinectes sapidus.
Abstract: 1. An increase in the rate of antennule flicking and gill bailing upon presentation of sea water solutions of a freeze-dried clam extract indicated detection of sapid substances by the blue crab, Callinectes sapidus.2. The threshold concentration at which crabs detected the sapid solution was 10-15 g/liter. Feeding behaviors were released at higher concentrations, 10-1 to 10-2 g/liter.3. Food deprivation for six days lowered the threshold for feeding behaviors but did not affect the detection threshold.

80 citations


Journal ArticleDOI
TL;DR: The regional distribution of cutter fibers correlates with previous physiological studies on the distribution of the fast and slow motor axons to these muscle fibers.
Abstract: 1. The closer muscles of the dimorphic claws (chelipeds) were studied for the presence and location of fast and slow muscle fibers.2. Cutter claws were composed of about 60-70% short sarcomere ( 6 µm) slow and intermediate (4-6 µm) fibers.3. Crusher claws were composed of a uniform population of long sarcomere (6-13 µm) slow and intermediate (4-6 µm) fibers.4. There was a regional distribution of fibers in the cutter claw. Ventral fibers were predominantly slow. Dorsal fibers and central medial fibers were fast. Proximal and distal fibers in the medial section were usually mixed.5. The regional distribution of cutter fibers correlates with previous physiological studies on the distribution of the fast and slow motor axons to these muscle fibers.

76 citations


Journal ArticleDOI
TL;DR: The number of right-handed and left-handed males of Uca lactea were nearly equal, and no significant regional or yearly differences from the ratio of 1:1 were found.
Abstract: 1. The numbers of right-handed and left-handed males of Uca lactea were nearly equal, and no significant regional or yearly differences from the ratio of 1:1 were found.2. In the early stages of growth, all the crabs had two small chelipeds, and no morphological differences were found between the sexes. All males with a carapace width greater than 5.3 mm exhibited cheliped asymmetry. Apparently, a male normally loses one of his chelipeds which then regenerates into a small cheliped; the remaining cheliped develops into a giant, and the male attains his cheliped asymmetry.3. Artificial removal of one cheliped from megalopae and young crabs whose chelipeds were still in the symmetrical condition induced handedness. The large cheliped always developed on the intact side.4. When males suffered the simultaneous removal of both chelipeds in their megalopa or crab stage before the attainment of asymmetry, they could not develop a giant cheliped but instead kept two small chelipeds permanently. However, no abnorm...

69 citations


Journal ArticleDOI
TL;DR: The minimum amount of salinity decrease from the acclimation salinity that induces a reversal in phototactic sign from positive to negative phototaxis at 0.19 Wm-2 ranges from 1 to 2‰, and appears to be independent of acclimat...
Abstract: 1. Experiments were conducted to determine the effect of salinity on phototaxis and geotaxis by Stages I and IV zoeae of the crab, Rhithropanopeus harrisii.2. Larvae were exposed to sudden salinity changes and stimulated with various intensities of 500-nm light in the horizontal plane. Although the pattern of phototaxis of larvae exposed to 40‰ was unchanged from that at 20‰ (acclimation salinity), the level of positive phototaxis to higher intensities was significantly greater and the level of negative phototaxis to low intensities significantly lower at 40‰. Exposure to low salinity sea water (5‰) generally reverses the sign of phototaxis, since a significantly higher level of negative phototaxis and lower level of positive phototaxis occurs at light intensities above 10-2 Wm-2.3. The minimum amount of salinity decrease from the acclimation salinity that induces a reversal in phototactic sign from positive to negative phototaxis at 0.19 Wm-2 ranges from 1 to 2‰, and appears to be independent of acclimat...

68 citations


Journal ArticleDOI
TL;DR: Results of assay of various internal tissues of blue crabs, Callinectes sapidus, finding high activity of arylhydrocarbon hydroxylase in the stomach and green gland are presented, and it is noted that the green gland activity of this enzyme varies at different stages of maturity and molt cycle in a manner similar to insects.
Abstract: We have presented results of assay of various internal tissues of blue crabs, Callinectes sapidus, finding high activity of arylhydrocarbon hydroxylase in the stomach and green gland. Also we have noted that the green gland activity of this enzyme varies at different stages of maturity and molt cycle in a manner similar to insects. We have speculated as to why an excretory organ should have such high activity and undergo such fluctuations in activity.

Journal ArticleDOI
TL;DR: Ba et al. as mentioned in this paper investigated the population genetics of American lobsters (Honiarits ainericanus M-E) and revealed both a low level of genetic variation within populations relative to other invertebrates, and little genetic differentiation between populations.
Abstract: Bodega Ba@', Califor,iia 94923 In the course of investigating the population genetics of American lobsters (Honiarits ainericanus M-E) andits implications for fisheries nianagement and aquaculture, a survey of electrophoretically detectable protein variation was con ducted ( Tracey, Nelson, Hedgecock, Shleser and Pressick, 1975 ) . This study revealed both a low level of genetic variation within populations relative to other invertebrates, and little genetic differentiation between populations. In order to evaluate the potential of hybridization as a breeding program, it became iniportant to exalliine genetic variation in the European lobster, H. gain warns (L), and to determine the degree of protein divergence between these two species of the genus. The results of this study are reported here. The low level of protein divergence which was found, when contrasted with the morphological distinctness of the two species at all stages from egg to adult, has a bearing on the notion that protein evolution arid biological (or organismal) evolution may proceed relatively independently of one another, at quite different rates (see, for example, King and Wilson, 1975).

Journal ArticleDOI
TL;DR: The general larval trend of hyper-osmoticity over wide ranges of external salinities may serve to increase the density of the larva, helping to promote retention within the estuary, and may also act to provide turgor p...
Abstract: 1. Blood osmotic concentrations in the three zoeal stages, megalops stage, and adults were determined over a wide range of salinities for the estuarine, grapsid crab, Sesarma reticulatum Say.2. Larvae are hyper-osmotic over the salinity range 10 to 35‰ and hyper- or isosmotic at 40‰ throughout zoeal and early megalopa life. Older megalops display increased hyper-osmoticity at 10 and 40‰, compared to earlier zoeal stages.3. Adult specimens of S. reticulatum are hyper-osmotic in the salinity range 5 to 27.5‰, and hypo-osmotic in salinities > 27.5‰. The adult response is apparently attained during early juvenile crab stages.4. The effects of molting on blood osmotic concentrations is discussed. The rapid molting cycles of the larvae do not affect the blood osmotic concentration.5. The general larval trend of hyper-osmoticity over wide ranges of external salinities may serve to increase the density of the larva, helping to promote retention within the estuary. Hyper-osmoticity may also act to provide turgor p...

Journal ArticleDOI
TL;DR: Field studies of pH and PO2 values in burrows of C. californiensis indicate that animal movement may play a large part in water exchange between the surface and burrow, and activity studies suggest that oxygen is not critical to C. Californienis on a short term basis.
Abstract: 1. The pleopods of C. californiensis, a potential site for extrabranchial oxygen exchange, do not contribute significantly to oxygen consumption.2. C. californiensis has a gill surface area of 4.13 ± 0.72 cm2/g wet body weight, the lowest value yet reported for a totally aquatic crustacean.3. C. californiensis, when placed in simulated burrow conditions, regulates the PO2 very loosely in its immediate microhabitat, using its pleopods.4. Field studies of pH and PO2 values in burrows of C. californiensis indicate that animal movement may play a large part in water exchange between the surface and burrow.5. Activity studies suggest that oxygen is not critical to C. californiensis on a short term basis. Perception of oxygen after long deprivation may signal the possibility of renewed feeding and activity at the surface of its burrow.

Journal ArticleDOI
TL;DR: Light, transmission electron and scanning electron microscopy of a cerianthid anemone reveal that the protective tube with which the animal surrounds itself is composed almost entirely of discharged, interwoven cnidae of a heretofore undescribed type.
Abstract: Light, transmission electron and scanning electron microscopy of a cerianthid anemone reveal that the protective tube with which the animal surrounds itself is composed almost entirely of discharged, interwoven cnidae of a heretofore undescribed type.As opposed to the threads of all nematocysts and spirocysts described to date, the thread of the new cnida, to which has been given the name of ptychocyst, is not helically folded, forming a variable number of pleats in circumference (from 5 to 11 observed in the present study), and no pleats in length. The discharged threads are quite long (over 2 mm in some) and are non-isodiametric, tapering from a diameter of about 5 µm at the base to about 2 µm at the tip for an overall reduction in diameter of 2.5 times.The everted thread has a number of fine ridges running along its length which can be seen using phase contrast microscopy and which represent the folds by which the thread is compressed in diameter. The thread tip is closed and the entire thread is unarm...

Journal ArticleDOI
TL;DR: Characteristics of the influx and net flux of amino acids in Mytilus californianus are consistent with a sodium-coupled mechanism for the transport of amino acid into gill tissue, but energetic considerations cast doubt on the adequacy of such a mechanism to account fully for the observed trans-epidermal transport.
Abstract: 1. Intact mussels and an in vitro preparation of isolated gill tissue were employed to study characteristics of the influx and net flux of amino acids in Mytilus californianus.2. The kinetics of influx of 14C-labelled amino acids were complicated by the presence of a rapidly labelled extracellular compartment.3. Correction of influx data for the extracellular compartment revealed influx of 14C-cycloleucine and 14C-glycine to be mediated by a transport mechanism adequately described by Michaelis-Menten kinetics. Passive diffusion plays no significant role in influx.4. Influx and net flux of glycine into intact Mytilus were examined. From high concentrations (> 20 µM) the influx of 14C-glycine was equivalent to the net influx of primary amine as determined by fluorescamine. At low ambient concentrations (< 20 µM), influx of 14C-glycine occurred more rapidly than net influx as determined by fluorescamine. The data suggest that influx of labelled substrate is accompanied by efflux of unknown primary amine(s)....

Journal ArticleDOI
TL;DR: The rapid sexual maturation observed and the small size of eggs ready to be spawned indicates that the one year life cycle previously proposed for Illex illecebrosus is feasible.
Abstract: 1. Female specimens of Illex illecebrosus of 20 to 28 cm mantle lengths lived, fed and grew in a 15 m diameter pool for periods up to 82 days; deaths during the first week were associated with skin damage during capture and those after the eighth week with precocious sexual maturation.2. Under the conditions described, squid survived repeated capture and urethane anesthesia, as well as tattooing and surgical procedures. Techniques for handling are described.3. Although the cause of early maturation is not certain, squid entering the pool were exposed to increased photoperiods, and a relationship is hypothesized between this stimulus and the natural November spawning migration.4. The rapid sexual maturation observed and the small size of eggs ready to be spawned indicates that the one year life cycle previously proposed for Illex illecebrosus is feasible.

Journal ArticleDOI
TL;DR: The shell exploitation of hermit crabs inhabiting a subtidal region of Beaufort Harbor (N. C.) was studied to determine the importance of shell resource partitioning in allowing the coexistence of the herMIT crabs.
Abstract: The shell exploitation of hermit crabs inhabiting a subtidal region of Beaufort Harbor (N. C.) was studied to determine the importance of shell resource partitioning in allowing the coexistence of the hermit crabs. The three most abundant species (Pagurus annulipes, P. longicarpus, and P. pollicaris) partition the size range. The size ratio between the larger species (P. pollicaris and P. longicarpus) was 1.7 and the size ratio between the smaller species (P. annulipes and P. longicarpus) was only 1.2. Differences in shell species utilization were significant only for the smaller species (P. annulipes and P. longicarpus). Specimens of four other hermit crab species were collected (Pagurus brevidactylus, Pagurus impressus, Paguristes hummi, and Petrochirus diogenes). Individuals of these species are more prevalent offshore. In Beaufort Harbor they use relatively small shells or shells which tend to be overlooked or shunned by the other species.Experiments on shell selection, interspecific fighting, and sub...

Journal ArticleDOI
TL;DR: Moina macrocopa was cultured aseptically for more than 200 parthogenetic generations in a nearly-defined medium without losing fertility in a biphasic medium, and was found to require cholesterol, nucleic caids, thiamine, nicotinamide, pyridoxine and folic acid in the presence of liver infusion.
Abstract: 1. Moina macrocopa was cultured aseptically for more than 200 parthogenetic generations in a nearly-defined medium without losing fertility.2. A biphasic medium was used. The liquid phase supplied minerals, B-vitamins, amino acids, liver infusion and nucleic acids. The fine particulate phase consisted of egg albumin, albumin fraction V, starch and lipid factors.3. The particulate phase was essential for rapid growth, taking advantage of the food gathering efficiency of filter feeders.4. Developmental time, brood size and sustained fertility depended on calciferol, tocopherol and saturated and unsaturated fatty acids; B carotene or retinol favored fertility but might not be essential.5. Moina was found to require cholesterol, nucleic caids, thiamine, nicotinamide, pyridoxine, Ca pantothenate and probably riboflavin and folic acid in the presence of liver infusion, the only undefined and required component of the medium.6. Ratios and quantities of the nutrients were important for media efficiency: excess vi...

Journal ArticleDOI
TL;DR: Survey studies carried out over a four year period revealed a general pattern of temporal constancy in allele frequency in all three species, suggesting that North American specimens of L. littorea are not recent colonists from Europe and have passed through a severe population bottleneck on the North American continent.
Abstract: Gene-enzyme variation was examined at ten to fifteen loci in three sympatric species of Littorina collected from Cape Cod, Massachusetts and Roscoff, Brittany. The North American and French populations of L. saxatilis and L. obtusata were, in general, quite similar in allele content and frequency. In contrast, the North American and French populations of L. littorea were genetically differentiated at a majority of their loci. This pattern of heterogeneity in the three species, along with calculated values of average heterozygosity, suggests that North American specimens of L. littorea are not recent colonists from Europe and have passed through a severe population bottleneck on the North American continent. Survey studies carried out over a four year period revealed a general pattern of temporal constancy in allele frequency in all three species.

Journal ArticleDOI
TL;DR: Although gene frequencies were significantly different among Atlantic populations, the overall values of genetic distance were within the range observed for geographic populations of other species.
Abstract: Genotypic variation, inferred from isozyme differences in twelve enzyme systems, was measured by means of horizontal microacrylamide gel electrophoresis in four populations of the sea urchin, Arbacia punctulata, from the Atlantic coast of the United States. An additional population from the Gulf of Mexico was surveyed for four enzymes. Although gene frequencies were significantly different among Atlantic populations, the overall values of genetic distance were within the range observed for geographic populations of other species. A balance between migration and selection is proposed to account for the patterns of genetic variation. Striking differences in gene frequency were not observed when Atlantic coast populations were compared with Gulf of Mexico specimens.

Journal ArticleDOI
TL;DR: The genetic analysis indicated substantial genetic variation in larval length measured 16 days after fertilization, as well as significant genetic interaction with salinity interpreted as the presence of genes influencing larval growth which depend on salinity for their expression and may be related to the past selective influence of a fluctuating environment.
Abstract: 1. Adult specimens of Mytilus edulis in spawning condition were collected from a shallow, enclosed bay which was known to experience fluctuations in salinity. Growth of the resulting larvae was measured under different salinity conditions in the laboratory.2. There was no significant difference in mean length between larvae raised at 30‰ and those raised at 18‰ after 18 days of growth. Salinities below this significantly decreased growth.3. Families of larvae of known parentage were raised at different salinities.4. The genetic analysis indicated substantial genetic variation in larval length measured 16 days after fertilization, as well as significant genetic interaction with salinity.5. This is interpreted as the presence of genes influencing larval growth which depend on salinity for their expression and may be related to the past selective influence of a fluctuating environment.6. These quantitative genetic techniques provide a useful approach to studying genetic variation in marine organisms and its ...

Journal ArticleDOI
TL;DR: Identification of the primordial crystal population within membrane-bound visicles provides overwhelming evidence for the intracellular mode of calcification in Scleractinia and permits development of a novel concept of cellular regulation over these dynamic events.
Abstract: Orthorhombic aragonitic crystals, embedded with a granular lipo-protein matrix and surrounded by a trilaminar membrane, are localized in the apical cytoplasm of epidermal cells of Scleractinian corals. Adult specimens of Astrangia danae (Agassiz) and settled planulae of Porites porites (Pallas) contain crystals averaging 0.7 mu by 0.1 mu by 0.3 mu within Golgi-derived vesicles. Short-term labelling with 45Ca reveals distribution of radioactivity amont a basic tissue fraction (92%) an acid tissue fraction (5%) and a skeletal fraction (3%). Identification of the primordial crystal population within membrane-bound visicles provides overwhelming evidence for the intracellular mode of calcification in Scleractinia. Moreover, it permits development of a novel concept of cellular regulation over these dynamic events. The membrane-bound vesicel is a miniature crystal fabrication station and a vehicle responsible for transportation of seed crystals and an organic matrix material to sites of discharge from the cell. The vesicle membrane becomes a probable locus of active transport and enzymatic activity as well as a physical barrier to be penetrated for release of vesicle contents into the extracellular milieu. Contact between the vesicle membrane and the plasmalemma would result in exocytosis and the onset of skeletogenesis. Principles governing crystal growth would prevail from then on. The released crystal becomes a nucleation catalyst and the organic matrix, a supply of ionic calcium for self-limiting crystallization. Crystals are produced by the organism spontaneously and continuously from shortly after larval attachment throughout the life of the polyp. Therefore, these membrane-bound vesicles signal the dynamic process by which initiation, differentiation, growth and limitation of the coral skeleton is regulated.

Journal ArticleDOI
TL;DR: It is concluded that corpora allata and juvenile hormone are not required for the initial appearance and synthesis of vitellogenin in the Cecropia silkworm.
Abstract: 1. The involvement of corpora allata and juvenile hormone in vitellogenin synthesis in the Cecropia silkworm was examined.2. Allatectomy of diapausing pupae did not alter the pattern of 3H-leucine incorporation into vitellogenin during their late pharate adult development.3. Allatectomy of early fourth and fifth instar caterpillars did not prevent the appearance of vitellogenin in these operated animals when they had transformed into miniature pupae or pupal-adult intermediates.4. Injection of a synthetic dl-JH into isolated diapausing abdomens did not stimulate the incorporation of 3H-leucine into vitellogenin.5. It is concluded that corpora allata and juvenile hormone are not required for the initial appearance and synthesis of vitellogenin in the Cecropia silkworm.

Journal ArticleDOI
TL;DR: The hypothesis that such osmolytes are innocuous and substitute for more deleterious salts at high osmotic pressures was tested on a representative macromolecule, the enzyme lactate dehydrogenase (LDH), from the euryhaline polychaete, Nereis succinea.
Abstract: 1. In searching for an explanation for the high intracellular concentrations of nitrogenous organic osmolytes found in all marine invertebrates, the similarity of their functional groups to those neutral salts known to stabilize native macromolecular conformations was noted. This led to the hypothesis that such osmolytes are innocuous and substitute for more deleterious salts at high osmotic pressures. The hypothesis was tested on a representative macromolecule, the enzyme lactate dehydrogenase (LDH), from the euryhaline polychaete, Nereis succinea.2. The activity of LDH from worms adapted to a range of salinities was measured at several pH values and in the presence of various concentrations of neutral salts and of low molecular weight nitrogenous solutes characteristically found intracellularly in marine and euryhaline invertebrates.3. Differences in LDH activity in homogenates from worms adapted to osmoconforming (100%-35% SW) and osmoregulating (20% SW) salinities were observed. Enzyme activity from o...

Journal ArticleDOI
TL;DR: Crangon handi is a specialist for shallow-water coarse sand substrates and here exhibits remarkable crypsis, and L. stylirostris are squat shrimps in restricted habitats probably adapted for short quic...
Abstract: 1. Crangon handi, new species. is described and compared with five other California crangonid shrimps; it occurs from the littoral zone to 55 m from Sonoma County to Bahia Colnett. northern Baja California. Crangon handi is a specialist for shallow-water coarse sand substrates and here exhibits remarkable crypsis. Crangon handi eats small gammarid amphipods and has in turn been found in the stomach of the thornback skate.2. Lissocrangon, new genus, is proposed to accomodate C. stylirostris, a species lacking gastric spination; Crangon is restricted to shrimp with one gastric spine; Steiracrangon Kinahan, is revived for shrimp with bicarinate sixth abdominal segments; and Neocrangon Zarenkov is revised and amended to include shrimp with two gastric spines and bicarinate sixth abdominal segments.3. Morphological analyses and relative growth are presented and discussed for all six crangonids considered. Crangon handi and L. stylirostris are squat shrimps in restricted habitats probably adapted for short quic...

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TL;DR: Effects of ingestion and topical application of 1.30 ppm methoprene, an insect juvenile hormone (JH) mimic, include gametogenesis disorders in both male and female mud-crab Rhithropanopeus harrisii and analogies between these results and those obtained from experiments involving androgenic gland implantations or the consequences of their hyperfunctioning are discussed.
Abstract: 1. Effects of ingestion and topical application of 1.30 ppm methoprene, an insect juvenile hormone (JH) mimic, include gametogenesis disorders in both male and female mud-crab Rhithropanopeus harrisii. 2. Progressive inhibition of vitellogenesis and stimulation of spermatogenesis take place after a short exposure time (12-15 days), whereas a longer period (between 30 to 45 days) promotes inhibition of both spermatogenesis and vitellogenesis. Such modifications demonstrate the chemosterilizing action of methoprene on crustaceans. 3. Stoppage of vitellogenesis is characterized by a blockage of oocytes at terminal previtellogenesis and proliferation of the follicle cells involved in vitellogenic oocyte lysis. Spermatogenic degeneration begins with the amalgam of spermatocyte clusters in meiotic prophase and pycnosis of gonia. 4. Analogies between these results and those obtained from experiments involving androgenic gland implantations or the consequences of their hyperfunctioning are discussed.

Journal ArticleDOI
TL;DR: There is evidence to suggest that the source and nature of agglutinins from Helisoma and Biomphalaria species are different and Lectins may be of some value in characterizing snail populations and as an aid in the taxonomic discrimination of species.
Abstract: 1. Thirty-one strains representing eight species and four genera of the molluscan family Planorbidae were surveyed for the presence of hemagglutinins and hemolysins. Extracts prepared from albumen-glands and egg-masses, as well as hemolymph, were assayed by a micro-hemagglutination technique in which human erythrocytes were used as receptors.2. Hemagglutinins and hemolysins for human erythrocytes were not uniformily present in all members of the family and detection of these substances depended, in part, on the material tested.3. Neither heating to 56° C, dialysis, storage at -20° C for up to a year, nor repeated freezing and thawing appeared to effect the agglutinating activity of egg or albumen-gland extracts.4. Inhibition of the agglutinating activity of Helisoma hemolymph could be accomplished with N-Acetyl-D-Galactosamine, but this sugar had no effect on the activity of Biomphalaria agglutinins.5. There is evidence to suggest that the source and nature of agglutinins from Helisoma and Biomphalaria sp...

Journal ArticleDOI
TL;DR: A case of shell color ploymorphism in the shallow water mesogastropod Crepidula convexa is described, where the necessary and sufficient criteria for a stable polymorphism are met, but reasons are set forth for believing that this is, rather, a case of unstable polymorphism.
Abstract: A case of shell color ploymorphism in the shallow water mesogastropod Crepidula convexa is described. Polymorphism of color in C. convexa appears to be based on disruptive selection, which occurs due to the availability of two contrasting shades of substrate, heterogeneous in time and space, combined with mortality from visual predators.Data on the relative survival of the two phentoypes of C. convexa in two patches of a heterogeneous environment are applied to the fitness set model developed by Levins (1968). The necessary and sufficient criteria for a stable polymorphism are met, but reasons are set forth for believing that this is, rather, a case of unstable polymorphism.Only one other species of the genus, C. adunca, shows a similar color polymorphism. Ecological factors uniquely shared by the two species are: visibility of inherited shell color, a major part of the population living in the intertidal zone, and an impact by visual predators. Color polymorphism is correlated with visual predation on a ...

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TL;DR: The sea urchin ovary has a clearly defined state in which nutrient globules are produced and stored in accessory cells, and it is proposed that the cytoplasm of relict ova is disrupted by the activity of their lysosomes.
Abstract: 1. Specimens of the sea urchins, Anthocidaris crassispina and Hemicentrotus pulcherrimus, were collected each month, their ovaries were fixed and embedded in Epon 812, and thick sections were observed with the light microscope.2. The sea urchin ovary has a clearly defined state in which nutrient globules are produced and stored in accessory cells. Especially in Hemicentrotus pulcherrimus, this state continued from May to November. The number of globules in the accessory cells fluctuated with the course of the reproductive cycle.3. Toward the end of the breeding season, strong acid phosphatase activity was detected in the unshed (relict) ova as they degenerated, and numerous large mosaic globules containing cortical granules appeared in the accessory cells. It is proposed that the cytoplasm of relict ova is disrupted by the activity of their lysosomes.