Showing papers in "The Biological Bulletin in 1974"
TL;DR: It is suggested that the choroid rete mirabile, acting in concert with the pigment cell layer of the retina, plays an essential part in establishing the large oxygen pressure at the retina.
Abstract: Vascular counter-current systems in which the vessels are of capillary dimen sions have been described for the mammalian kidney, the swimbladder of teleost fish (Woodland, 191 1 ; Harden Jones and Marshall, 1953), and the choroid layer subtending the retina of the fish eye. Albers ( 1806) was the first to show that the large, horseshoe-shaped body in the choroidal layer of the eye of fish was neither a muscle nor a gland as was then supposed but an aggregation of small blood vessels. These vessels originate from a branch of the ophthalmic artery and their outflow supplies the choriocapiilaris, the dense capillary bed underlying the retina (Muller, 1839 ; Jones, 1838) . Muller (1839) pointed out that all the blood to the choroidal vessels had first to pass through the pseudobranch. Allen (1905) injected the vessels of the choroidal circulation and later ( 1949) gave a detailed account of them. He pointed out that the blood flowing to the eye in the ophthalmic artery is oxygenated at the gills and, in many species, again comes in contact with sea water at the pseudobranch. Jones ( 1838) introduced the now preferred name for the choroidal vascular structure—the choroid rete mirabile. Barnett ( 195 1) gives by far the most detailed description of the choroidal circu lation. It is based on dissection of injected preparations and on serial sections of whole eyeballs or whole heads. Johannes Muller ( 1839), Richard Owen (1836) and T. Wharton Jones (1838) had each recognized that the arterial and venous capillaries making up the choroid rete mirabile are arrayed in parallel. It remained for Barnett ( 1951) to realize that the arterial and venous blood streams flow counter-current one to another in the capillaries of the choroid rete mirabile. In addition to the choroid rete mirabile, Barnett (1951) describes a similar, smaller structure, the lentiform body, also supplying blood to the choriocapillaris. It appeared to us that the pigment cell epithelial layer of the retina is at least formally analogous to the gas gland of the swimbiadder (Wittenberg and Witten berg, 1962). These relations are diagrammed in Figure 1. In each instance a capillary counter-current organ, a rete mirabile, supplies arterial blood to a capillary network, underlying an epithelial layer, respectively the pigment cell layer of the retina and the gas gland of the swimbladder, and in turn receives the venous out flow from these capillaries. The structural resemblance between the swimbladder
158 citations
TL;DR: With the development of a culture technique for sea urchins (Hinegardner, 1969), large and uniform populations of healthy animals became available for study and metamorphosis of these animals was described.
Abstract: Many benthic marine animals release their gametes, embryos, or larvae into the water column. The offspring subsequently enter the adult population through settlement and metamorphosis. Sea urchins are one such animal. They have highly differentiated larvae that undergo a complex metamorphosis. The scant information on their metamorphosis
has been reviewed by Hyman (1955). MacBride (1903) was the first to prepare a comprehensive description of metamorphosis. He used Echinus esculentus eggs that were fertilized in the laboratory. The larvae were fed on organisms collected along with the seawater in which they were raised. Earlier workers used field-collected larvae. Neither of these methods could have yielded consistently healthy and uniformly developing animals. With the development of a culture technique for sea urchins (Hinegardner, 1969), large and uniform populations of healthy animals became available for study.
157 citations
TL;DR: The vanadium and other selected metal contents of primarily California ascidians have been determined and three dominant fractions were chromatographed from the cells contained in the fluid of Ascidia ceratodes.
Abstract: The vanadium and other selected metal contents of primarily California ascidians have been determined. The species Ascidia ceratodes and Perophora annectens have large vanadium contents as has been predicted for members of the families Ascidiidae and Perophoridae from the order Phlebobranchia. Several species in the order Aplousobranchia have large vanadium contents: the vanadium being present as vanadium (IV) whereas it is vanadium (III) that is found in the order Phlebobranchia. Molgula manhattensis, a species from the order Stolidobranchia, shows a large iron content: the metal being localized in the fluid from the heart.Three dominant fractions were chromatographed from the cells contained in the fluid of Ascidia ceratodes. The roles of the compounds present in these fractions are discussed. The spectra of these fractions are correlated with the spectrum of the cells.
106 citations
TL;DR: Findings support the choice of Drosophila for resolving the genetic basis of juvenile hormone action and support the critical developmental stage and dose-response relationships.
Abstract: Topical application of Cecropia juvenile hormone (JH) blocked metamorphosis of the abdominal integument of pupating Drosophila larvae. JH treated adult flies retained more or less extensive areas of cuticle which could not be distinguished from pupal cuticle in whole mounts. Implantation into mature larvae of fragments of first instar larvae containing brains and ring glands provoked localized retention of patches of incompletely metamorphosed cuticle. An assay procedure for compounds with juvenile hormone activity was developed by defining the critical developmental stage and dose-response relationships. Twenty-two substances suspected of having juvenile hormone activity were assayed for their effect on Drosophila. These findings support the choice of Drosophila for resolving the genetic basis of juvenile hormone action.
101 citations
TL;DR: Sexually mature Placopecten magellanicus from Isles of Shoals, New Hampshire, were observed to spawn in nature at 14°-16° C and in the laboratory, spawning occurred from 10°-15° C.
Abstract: (1) Sexually mature Placopecten magellanicus from Isles of Shoals, New Hampshire, were observed to spawn in nature at 14°-16° C. In the laboratory, spawning occurred from 10°-15° C.(2) Average sizes of developmental stages were: eggs, 64 microns diameter; swimming gastrula, 69 microns long by 63 microns diameter; earliest straight-hinge veliger, 105 x 82 microns, with a hinge line of 81 microns. The umbo stage began in larvae exceeding 175 x 155 microns. Pediveligers averaged 279 x 242 microns with a depth of 127 microns, and were inequivalved, the left valve being larger.(3) Development from the zygote to the swimming gastrula took 30-40 hours at 12° C. The straight-hinge veliger stage was reached in four days at temperatures between 12° and 18° C.(4) Veligers reared at 15° C reached the pediveliger stage in 28 days, and the first spat was observed on the 35th day. Veligers reared at 19° C suffered a mass mortality when approximately half grown.(5) Larvae remained viable at salinities as low as 10.5‰, an...
97 citations
TL;DR: An energy budget was constructed for Menippe mercenaria from hatching to first juvenile crab when fed newly-hatched Artemia nauplii when the growth rate decreases during megalopa andpiration by zoea is proportional to the two thirds power of body weight.
Abstract: 1. An energy budget was constructed for Menippe mercenaria from hatching to first juvenile crab when fed newly-hatched Artemia nauplii.2. Larvae of M. mercenaria grow exponentially through the zoeal stages. Growth rate decreases during megalopa.3. Consumption reaches its peak during megalopa where one individual may consume 91 Artemia nauplii/day. Feeding rate decreases prior to molting to first crab stage.4. The caloric content per unit dry weight increases from 2.503 cal/mg at hatching to 3.746 cal/mg at first juvenile crab. Molts contain 1.296 cal/mg.5. Respiration by zoea is proportional to the two thirds power of body weight and is described by the function R = 0.0017W0.67.6. Over the period of larval development, 7.329 calories are consumed, 2.207 calories are used for growth, 0.502 calories are lost to production of exuvia, 1.933 calories are expended for maintenance, and 2.687 calories are lost as rejecta.
96 citations
TL;DR: The lysozyme from M. arenaria hemolymph is salt dependent, relatively heat stabile, very sensitive to alterations in ionic concentration and the presence of heavy metals, and has an optimal pH of 5.5 when 0.1 M Tris-HCl buffer is used.
Abstract: Lysozyme activity has been demonstrated in the hemolymph of the soft-shelled clam, Mya arenaria. When whole hemolymph is centrifuged at 4000 and 10,000 x g and each constituent is assayed, lysozyme activity is found to be greater in the two supernatants than in the corresponding pellets.The lysozyme from M. arenaria hemolymph is salt dependent, relatively heat stabile, very sensitive to alterations in ionic concentration and the presence of heavy metals, and has an optimal pH of 5.0 when 0.1 M glycylglycine, 0.1 M imidazole, or 0.1 M phosphate buffers are employed but an optimal pH of 4.5 when 0.1 M Tris-HCl buffer is used.A Hill plot of the data resulting from salt reactivation studies indicates that the lysozyme in M. arenaria hemolymph includes at least 2.0 interacting binding sites for NaCl and KCl.When tested against a number of bacteria, the lysozyme is most active against Micrococcus lysodeitikus and Bacillus megaterium. It is less active against Proteus vulgaris, Salmonella pullorum, Shigella sonn...
96 citations
TL;DR: The efficacy of the induction of passive flow depends in a complex manner on oscular geometry although, in general, sharp-edged, protruding apertures are the most effective exits.
Abstract: 1. If a sponge is exposed to moving water, it is physically possible for water to pass unidirectionally through it without active pumping by the choanocytes; mechanisms presented for such "passive flow" predict flow from ostia to oscula.2. In actively pumping Halichondria, water passes more rapidly from ostia to oscula in the presence of ambient currents; water flows through freshly killed Halichondria only when the surrounding medium is in motion.3. Quantitatively similar passive flow may be induced by motion of the medium in a variety of physical models of sponges.4. The efficacy of the induction of passive flow depends in a complex manner on oscular geometry although, in general, sharp-edged, protruding apertures are the most effective exits.5. These apparently novel results are consistent with much earlier literature on the structure, behavior, and ecology of sponges.
93 citations
TL;DR: In this paper, it was shown that there are minimal differences in food demands and digestive efficiencies between the sexes, yet the enlarged claw of the fiddler crabs cannot be used for feeding.
Abstract: 1. There were no differences in the respiratory rates of male and female Uca pugnax of comparable sizes.2. The amount of salt marsh sediment ingested by starved male and female crabs was similar.3. The number and weight of fecal pellets produced by male and female crabs were similar, as was the organic matter content.4. The above suggests that there are minimal differences in food demands and digestive efficiencies between the sexes, yet the enlarged claw of the fiddler crabs cannot be used for feeding. This requires some compensatory mechanism in male crabs.5. Male fiddlers do show about half the feeding motions per unit time compared to females, but they compensate by feeding about twice as long. This is corroborated by field observations.6. Further compensation, if needed, could be achieved by the slightly larger holding surface of the feeding claw in males, perhaps allowing the grasping of larger fragments of marsh sediment.
88 citations
TL;DR: Two species of hermit crab, Pagurus acadianus and P. pubescens are distributed sympatrically in offshore waters of Frenchman Bay, Maine and Laboratory and field investigations indicate that smaller sized specimens of P. academyianus have a preference for Littorina shells over Thais shells whereas P.pubescens individuals enter shells of either Thais or LITTorina depending on the relative abundance of each type.
Abstract: Two species of hermit crab, Pagurus acadianus and P. pubescens are distributed sympatrically in offshore waters of Frenchman Bay, Maine. Laboratory and field investigations indicate that smaller sized specimens of P. acadianus have a preference for Littorina shells over Thais shells whereas P. pubescens individuals enter shells of either Thais or Littorina depending on the relative abundance of each type. Larger P. acadianus individuals which usually exceed the size range of P. pubescens principally occupy shells of Buccinum and Polinices. P. acadianus shows a strong preference for mollusc shells colonized by Hydractinia echinata.Isolation increases the level of aggression in P. acadianus individuals, but the low levels of agonistic behavior found in tests with P. pubescens crabs appear not to be affected by changes in crab density. In both species, subjects in shells of too small a size by volume showed a high degree of dominance in trials over crabs occupying normal or large shells; a factor which can b...
88 citations
TL;DR: The choroid rete mirabile is a vascular counter-current organ located behind the retina of the eye and responsible in part for the maintenance of a high partial pressure of oxygen there.
Abstract: The choroid rete mirabile is a vascular counter-current organ located behind the retina of the eye and responsible in part for the maintenance of a high partial pressure of oxygen there. It is absent in cyclostomes, elasmobranchs, and all living non-teleost bony fishes with the exception of the holostean, Amia calva. The choroid rete is found widely distributed among teleosts and is nearly always present in the Acanthopterygii, which comprise the great majority of living forms. The ability to do without a choroid rete typifies families or orders, but is a character of limited phyletic usefulness. There seems little correlation between habitat and presence or absence of the choroid rete. The choroid rete and the rete mirabile of the swimbladder occur independently. This does not seem to be true for the choroid rete and the pseudobranch, Since almost all fishes which have a choroid rete also have a pseudobranch. Arterial blood comes to the choroid rete mirabile by way of the pseudobranch, and those instance...
TL;DR: In Manduca sexta females, follicles develop independently of the corpora allata until they reach a critical stage in late vitellogenesis, which prevents egg maturation as does extirpation of the brain from the pupa or decapitation of the adult.
Abstract: 1. In Manduca sexta females, follicles develop independently of the corpora allata until they reach a critical stage in late vitellogenesis. In the absence of juvenile hormone (JH), follicles then degenerate. When JH is present, the follicles continue development; they then become independent of JH for the final 12 hours of egg maturation.2. Allatectomy of the pupa of Manduca sexta or the newly eclosed adult female prevents egg maturation as does extirpation of the brain from the pupa or decapitation of the adult. The ability to develop follicles beyond the vitellogenic phase is restored by injection of synthetic JH or JH mimics.3. The brain activates the corpora allata close to the time of adult emergence. The glands secrete JH at a constant rate for 48 hours and then become less active in virgin, unfed moths.4. A female specific protein, identified by SDS gel electrophoresis, is present in adult blood and egg homogenates. Allatectomy has no effect on the concentration of vitellogenin in the blood nor on...
TL;DR: The shrimp have a preference for animal tissues of marine origin and grow best on these foods, but they have the ability to utilize food of microbial and terrestrial origins.
Abstract: Laboratory studies were conducted to compare growth rates of the estuarine sand shrimp Crangon septemspinosa on various natural and artificial diets. Field studies examined the types of food consumed by the shrimp.In nature, 85% of the material in the stomach is organic debris; sand, crustacean parts, copepods, plant material and polychaetes make up the remainder. Some of the organic debris results from trituration of ingested tissues, but an undetermined portion is ingested as detritus.In the laboratory, shrimp grow rapidly on diets of Artemia salina, Mercenaria mercenaria and hard-boiled egg. Fish meal, copepods, beef liver, tropical fish food, agar enriched with glycogen, bacteria, and Spartina alterniflora detritus with associated microflora are also utilized, but growth is retarded.Crangon septemspinosa utilizes a variety of foods. The shrimp have a preference for animal tissues of marine origin and grow best on these foods, but they have the ability to utilize food of microbial and terrestrial origins.
TL;DR: A study of the food-resource partitioning in the deposit-feeding polychaete Pectinaria gouldii collected from Little Sippewisset salt marsh, Massachusetts, shows that, on the average, larger worms select larger particles than smaller worms.
Abstract: 1. A study of the food-resource partitioning in the deposit-feeding polychaete Pectinaria gouldii collected from Little Sippewisset salt marsh, Massachusetts, shows that, on the average, larger worms select larger particles than smaller worms. Comparisons of ingested sediment with sediment collected where the animals were feeding indicate that the polychaetes prefer organic-encrusted mineral grains, floc aggregates, and fecal material.2. Histological stains were used to determine the percentage particle abundance of different possible food sources and fractions ingested by the polychaetes. Mercuric bromphenol blue (MBB) was used to stain protein-containing material and periodic acid Schiff reagent (PAS) was used to stain carbohydrate-protein complexes. Total possible organic material in the sediment averaged 32.7%. Very little of the sediment (less than 0.4%) stained with MBB, while an average of 13.9% of the sediment stained with PAS. Of the total possible organic matter, only about one-half stained with...
TL;DR: This report identifies the targets of oxygen and carbon dioxide in diapausing pupae of the Cecropia moth, discusses the interaction of carbon dioxide and oxygen in con trolling spiracular behavior, and analyzes several aspects of the nervous control of the spiracular closer muscle.
Abstract: In most insects spiracular valve movements are controlled by oxygen and carbon dioxide (Beckel and Schneiderman, 1957 ; Schneiderman, 1960 ; Levy and Schneiderman, 1966a, 1966b) . When the intratracheal concentration of carbon dioxide is high or that of oxygen is low, the spiracular valves open ; when the intratracheal concentration of oxygen is high, they close. However, the sites at which these gases act have never been demonstrated. The central nervous system is surely involved (Miller, 1966) as are the spiracles themselves. This report identifies the targets of oxygen and carbon dioxide in diapausing pupae of the Cecropia moth, discusses the interaction of oxygen and carbon dioxide in con trolling spiracular behavior, and analyzes several aspects of the nervous control of the spiracular closer muscle. MATERIALS AND METHODS
TL;DR: Pacific oysters are not able to sort purple bacteria from unicellular algae, but rapid digestion results in bacteria-free alimentary canal and faeces.
Abstract: 1. The pallium of the Pacific oyster comprises a restricted entrance and exit to a chamber separated by the ctenidium, analogous to a large diaphragm pump This configuration results in a low water velocity in the inhalant cavity.2. Separation and rejection of particles of high specific gravity occurs prior to impact upon the ctenidium, due to gravitational settlement because of the low pallial water velocity.3. Particles settling on the ctenidium are either rejected or carried in mucus to the labial palpi where the volume of mucus is reduced, and the concentrated food-mucus mass passed to the mouth.4. Pacific oysters are not able to sort purple bacteria from unicellular algae, but rapid digestion results in bacteria-free alimentary canal and faeces.
TL;DR: It is suggested that expansion and contraction of the anemones may play an important role in favorably regulating the amount of light to which their zooxanthellae are exposed.
Abstract: The pattern of expansion and contraction by the sea anemone Anthopleura elegantissima differs in individuals with or without endosymbiotic zooxanthellae. Anemones without zooxanthellae, found in dark habitats, do not regularly expand or contract under changes in light. Anemones with zooxanthellae expand in moderate light and contract in intense light or in darkness, with striking uniformity. However, this behavior does not always depend directly on the presence of zooxanthellae. Anemones that have previously had endosymbiotic zooxanthellae subsequently expand and contract with changes in light in the absence of these algae. Thus, conditioned responses may be involved. It is suggested that expansion and contraction of the anemones may play an important role in favorably regulating the amount of light to which their zooxanthellae are exposed.
TL;DR: It has been suggested that the colony specificity may be a feature being common to those ascidians in which fusion of test and/or blood vessels always occurs between the growing edges of its own.
Abstract: 1. The presence or absence of colony specificity, i.e., the recognition of self and not-self in colonial organisms, has been investigated with several species of compound Ascidians. If the reaction resulted from contact either between growing edges or between cut surfaces of colonies, fusion, rejection and indifference have been distinguished. Of these three cases, indifference means simply a defect of the other two. Both fusion and rejection are specific within the species.2. The presence of colony specificity has been demonstrated in Botryllus primigenus, Botrylloides violaceus. Symplegma reptans and Didemnum moseleyi. But, in Perophora orientalis colony specificity is absent.3. From the above facts, it has been suggested that the colony specificity may be a feature being common to those ascidians in which fusion of test and/or blood vessels always occurs between the growing edges of its own.4. In the process of fusion or rejection at the growing edges, two steps have been distinguished. The first step ...
TL;DR: The hematological parameters of Mercenaria mercenaria of similar size from two geographical areas as well as the morphology and behavior of their leucocytes were studied, revealing an insignificant correlation between the dimensions of whole animal and the differential count, packed cell volume and total cell count.
Abstract: The hematological parameters of Mercenaria mercenaria of similar size from two geographical areas as well as the morphology and behavior of their leucocytes were studied On the basis of qualitative and quantitative characteristics, three types of leucocytes, designated as granulocytes, fibrocytes, and hyalinocytes, can be distinguished in both living and stained preparationsA correlation matrix computed between all parameters considered has revealed an insignificant correlation between the dimensions of whole animal and the differential count, packed cell volume, and total cell count as well as an insignificant correlation between the hematological parameters themselves The only exception is that there is a positive correlation between the packed cell volume and the total cell count
TL;DR: The food and feeding mechanisms of this crab are determined and the morphological adaptations to a burrowing existence are assessed to assess the morphology of the appendages and visually verified by repeated observations.
Abstract: Ovalipes guadulpensis (Saussure) is a portunid commonly trawled from the sand bottoms along the northwestern Florida Gulf Coast. A sister species, 0. ocellatus (Herbst) , is reported to bury itself in the sand bottoms off North Carolina. When buried the respiratory currents are reversed and the crab emerges from the sand and actively “?�hunts†for food during rising or falling tides ( Pearse, Humm, and Wharton, 1942) . The habitats of the two species are similar, except adult 0. guadul/,ensis are usually not found near-shore (Williams, 1965). As no other information was available on the habits of 0. guadulpensis, a study was undertaken to determine the food and feeding mechanisms of this crab and to assess the morphological adaptations to a burrowing existence. MATERIALS AND METHODS Specimens of 0. guadulpensis were trawled from sand bottoms in the Gulf of Mexico along northwestern Florida in waters from three to eight meters in depth. Some individuals were preserved upon collection in 70% ethanol and then re frigerated. These crabs were used in stomach content analyses and morphological investigations. Other crabs were kept alive and returned to the laboratory and placed in running seawater aquaria. These were the subjects of observations on feeding, burrowing, and respiratory currents. Stomach contents and the gastric mill were investigated following the methods of Caine (1974). Motion pictures were made of both feeding and burrowing activity and the film was analyzed frame by frame. Analysis of the film was correlated with the morphology of the appendages and visually verified by repeated observations. Respiratory currents were tested using carmine to follow external currents and small quantities of methylene blue in a seawater solution to trace the internal water pathways.
TL;DR: 1. Ligumia subrostrata, removed from water will survive >40 days if dehydration is minimized by high relative humidity, and there is a significant shift of Cl from the tissues into the body fluids during dehydration.
Abstract: 1. Ligumia subrostrata, removed from water will survive >40 days if dehydration is minimized by high relative humidity. They are not anoxic but consume oxygen from the air (Qo2 59 µl O2/g dry tissue-hr). One source of energy is from the large glycogen stores (36% of dry tissue).2. Animals removed from water and exposed to either low relative humidity (45-55%) or N2 atmosphere will survive about 5-7days. The maximum total solute in the body fluids of surviving animals is 160-180 mOsmoles.3. Sodium, Cl, K, and Ca account for 72% of the total solute in the body fluids of fresh water acclimated animals. Dehydration increases the concentration of Na proportional to the amount of water lost. There is a significant shift of Cl from the tissues into the body fluids during dehydration.4. When the animals are out of water, forced anoxia increases the body fluid total solute but the Na and Cl contribution is small. The major ions in the body fluids are calcium and bicarbonate or succinate; reflecting a build up of m...
TL;DR: Inhibition of stenotele discharge is correlated with a gastral cavity filled with shrimp, but is not related to a rapid release of desmonemes in animals fed to repletion.
Abstract: 1) The pattern of nematocyst discharge was observed in hydra fed shrimp until repletion. Some time after cessation of ingestion stenotele discharge ceases, and at a later time desmoneme discharge is greatly diminished. Lack of capture of shrimp is not due to a rapid release of desmonemes in animals fed to repletion.2) Stenotele discharge remains severely inhibited until regurgitation of the remainder of the previous meal. Thereafter, stenotele discharge becomes progressively less inhibited and is normal 4-5 hours later.3) Discharge of stenotele mounted on the body column is partially inhibited in animals fed to repletion, but far less inhibited than for the stenoteles in the tentacles.4) Cessation of stenotele discharge after feeding to repletion is not due to the absence of mature stenoteles, as there are at least twice as many mature stenoteles present in the tentacles as are needed to feed to repletion.5) Inhibition of stenotele discharge is correlated with a gastral cavity filled with shrimp, but is n...
TL;DR: A pronounced clinal divergence with increasing size strongly argues for an adaptive polymorphism in the larger mussels and Mechanisms for the observed excess of homozygote genotypes in almost all samples are discussed.
Abstract: 1. Samples of the mussel, Mytilus edulis, were taken from 16 sites on the northern shore of Cape Cod. The mussels were measured and their genotypes at the leucine-amino-peptidase (LAP) locus determined by electrophoresis.2. At two separate estuarine localities, Sandwich Harbor and Scorton Creek, a pronounced cline in slow allele frequencies in the larger mussels was found, with upstream sites showing characteristically low frequencies (about 15%) and downstream (entrance) sites having high frequencies (45% to 55%). Mussels smaller than 26 mm had intermediate (22% to 35%) slow frequencies.3. This clinal divergence with increasing size strongly argues for an adaptive polymorphism. Mechanisms for the observed excess of homozygote genotypes in almost all samples are also discussed.
TL;DR: It is suggested that light-dark transitions are important in synchronizing locom motor activity rhythms and that locomotor activity is not a good indicator of possible circadian oscillations in this species.
Abstract: Atlantic salmon parr exposed to a 12 hr light-12 hr dark cycle (LD 12:12) for ten days were entrained to a 24.0 hr periodicity in locomotor activity. Thirty-five fish were light-active, 20 were dark-active and 32 were active primarily when lights were turned on or off. Fish maintained in constant conditions (75) were generally aperiodic. Five fish (of 30) in constant darkness (DD) showed evidence of 24.0 hr periodicity. Twelve fish exposed to a light signal of 1 hr duration recurring every 23 hr failed to become entrained. Fish in constant light (LL) showed more activity than fish in DD. The results suggest (1) that light-dark transitions are important in synchronizing locomotor activity rhythms and (2) that locomotor activity is not a good indicator of possible circadian oscillations in this species.
TL;DR: It is suggested that the flexible phototactic behavior of the anemone may play an important role in favorably regulating the amount of light to which the zooxanthellae are exposed.
Abstract: The sea anemone Anthopleura elegantissima, with and without endosymbiotic zooxanthellae, was tested for evidence of phototactic behavior. Anemones with zooxanthellae always displayed phototaxis, either positive or negative depending on the experimental light intensity and the light intensity of the habitat from which the animals were taken. Anemones without zooxanthellae—even those that had previously harbored zooxanthellae and that were genetically identical clone-mates of phototactic individuals—never displayed phototaxis, appearing completely indifferent to light and shade.The results indicate that phototaxis in this sea anemone depends directly on the presence of its symbiotic algae. It is suggested that the flexible phototactic behavior of the anemone may play an important role in favorably regulating the amount of light to which the zooxanthellae are exposed.
TL;DR: O. mülleri was present on the gills of most crab species in Beaufort Inlet but not on C. sapidus further upriver indicating that salinity is probably a factor controlling the incidence of the barnacle, and the factors affecting this distribution discussed.
Abstract: During the summer of I 973 crabs were collected regularly from Beaufort Inlet, North Carolina and examined for the presence of the epizoic barnacle, Octolasmis mullen (Coker), within the branchial chambers. Tile blue crab, Callinectes sa/'idus Rathbun is the most COfll@OIl crab in Beaufort Inlet (Dudley and Judy, 1971 ) and was therefore chosen as the host for a detailed study of 0. ;niilleri. The life-history and migrations of C. sa/'idus (Van Engei, 1958 ; Cargo, 1958 ; Costlow and Bookhout, 1959 ; Tagatz, 1968 ; Judy and Dudley, 1970 ; Dudley and Judy, 1971) have been studied because this crab is exploited commercially. The migrations of this crab may also influence the life-histories of epizoites. The present study investigates tile occurrence, distribution and mode of attachment of the epizoic 0. mullen on the gills of C. sa/'idus and discusses the possible con relations with the life cycle and habits of the cral).
TL;DR: Luidia clathrata is a euryhaline echinoderm, responding to reduced salinities by coelomic fluid volume regulation and isosmotic intracellular regulation.
Abstract: (1) The asteroid Luidia clathrata becomes inactive when transferred from 27‰ sea water to l6‰, but recovers its activity within 48 hours.(2) The volume of intact animals increases with the initiation of the hyposmotic stress, but returns to somewhat above the original level within several days. This suggests regulation of the volume of the coelomic fluid.(3) The changes in the per cent hydration and level of ninhydrin positive substances in the podia and pyloric caeca of hyposmotically stressed animals indicate that intracellular isosmotic regulation occurs.(4) The increase in the rate of ammonia excretion of hyposmotically stressed animals suggests that the decrease in tissue NPS levels results from their catabolism.(5)Luidia clathrata is a euryhaline echinoderm, responding to reduced salinities by coelomic fluid volume regulation and isosmotic intracellular regulation.
TL;DR: Endosymbiotic algae require light for maximum reproduction and green hydra grown in the dark show a decrease in the number of their algal symbionts.
Abstract: 1. Under conditions of continuous illumination and daily feeding, individual specimens of Hydra viridis possess approximately 1.5 x 105 endosymbiotic algae.2. The endosymbiotic algae are found in greatest abundance in those digestive cells constituting the central growth region (Zone 2) of the hydra (≈ 19 algae/ digestive cell) with fewer algal cells (≈ 12 algae/digestive cell) residing in the hypostome, tentacles (Zone 1) and stalk and basal disc (Zone 3).3. Under steady-state growth in the light, the algae reproduce at approximately the same rate as the animal hosts—K = 0.380 and 0.385, respectively.4. Endosymbiotic algae require light for maximum reproduction and green hydra grown in the dark show a decrease in the number of their algal symbionts. The rate of algal decline in the dark is believed to result from a dilution of the standing crop by the continuous growth of the animal tissues. Support for this theory is based on the observation that the rate of algal decline in the dark (K = 0.258) approxi...
TL;DR: Both the critical photoperiod and the number of long or intermediate days required to terminate diapause decrease at the time of year when environmental photophases are rapidly increasing, probably taking place faster in nature than is indicated by responsiveness to static Photoperiods in the laboratory.
Abstract: 1. Responsiveness of diapausing Chaoborus americanus larvae to photoperiod increases with chilling. Both the critical photoperiod and the number of long or intermediate days required to terminate diapause decrease at the time of year when environmental photophases are rapidly increasing. Consequently, the transition from diapause-maintaining to diapause-terminating daylengths probably takes place faster in nature than is indicated by responsiveness to static photoperiods in the laboratory.2. After prolonged chilling, short days no longer maintain diapause and food alone suffices to evoke development. The switch from photoperiod-dependent to photoperiod-independent development takes place over only a ten day period.3. Energies of monochromatic light from 390 to 660 nm required to elicit 10%, 50%, and 90% development were determined by extending an otherwise white light, short-day regimen to long-day with monochromatic light at dawn or at dusk. Monochromatic light at 540 nm was most effective at evoking dev...
TL;DR: Evidence for the sensitivity of sea urchin speramtozoa to the toxic effects of heavy metal ions comes from experiments on the ability of chelating agents to prolong both the motility and fertilizing capacity ofSea urch in sperma tozoa.
Abstract: Intense activity of sea urchin spermatozoa follows dilution in sea water. The high performance level is of limited duration ; metabolism and motility decline to a low steady state and fertilizing capacity diminishes progressively with time (Tyler and Tyler, 1966) . This so-called “?�dilution effect†has been attributed to the action of trace amounts of heavy metal ions present in seawater on the respiratory enzymes of the spermatozoa (Rothschild and Tuft, 1950 ; Rothschild and Tyler, 1954) . Although there are numerous reports on the effect of various metal ions on the 02 consumption of sea urchin spermatozoa, quantitative data on the action of heavy metals on spermatozoan motility are not generally available. Rothschild and Tuft ( 1950) reported that small amounts (4 X l0@ M) of CuCl2 or ZnCl2 added to dense suspensions ( > 4 x 108 sperm/ml) of Echinus esculentus spermatozoa increased their level of 02 consumption, but had no effect on the respiration of dilute suspensions (< 4 X 10@ sperm/ml) . While these authors did not provide actual measurements, they stated that neither copper nor zinc had any effect on the swimming speed of the spermatozoa. Mohri ( 1956) found that CuCl2 or ZnCl2 at low concentration (10@ M) accelerated the 02 uptake of Hemicentrotus puicherrimus spermatozoa, but at a higher concentration ( lO@ M) inhibited it. According to Barron, Nelson, and Ardao ( 1948) , 5 x 10@ M HgC12 stimulates the respiration of Arbacia punctulata spermatozoa, but a concentration of 10@ M inhibits their 02 consumption. These investigators did not relate the effects on 02 uptake to the motile activity of the cells. Additional evidence for the sensitivity of sea urchin speramtozoa to the toxic effects of heavy metal ions comes from experiments on the ability of chelating agents to prolong both the motility and fertilizing capacity of sea urchin sperma tozoa. Rothschild and Tyler (1954) found that 10 micromolar ethylenediamine tetraacetic acid (EDTA ) depressed dilution-induced increase in 02 uptake and de layed senescence of Echinus esculentus spermatozoa. Tyler ( 1953) used a variety of agents which bind heavy metal ions—amino acids. diethyldithiocarbamic acid (DEDTC) , 8-hydroxyquinoline (oxine) , and a-benzoinoxime (cupron)—to pro long the life span and fertilizing capacity of sea urchin and sand dollar spermatozoa. Mohri ( 1956) also found that chelating agents would suppress the respiratory in creases observed on dilution of Henticentrotus puicherrimus sperm. The investi gators concluded that these agents act to depress respiration, and thereby prolong sperm motility and vial)ility. l)y binding heavy metals ordinarily present@ in the seawater.