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Showing papers in "The Biological Bulletin in 1969"


Journal ArticleDOI
TL;DR: From a comparison with dark controls it is concluded that photosynthetic products of zooxanthellae are translocated to host coral tissue and the skeletal organic matrix also acquires 14C.
Abstract: 1. The hermatypic coral, Pocillopora damicornis was incubated in the laboratory and in its reef habitat with Na214CO3 for 1-24 hours. Controls were incubated in darkness. 14C fixation in light exceeded that in darkness.2. Fractionation of corals labeled on the reef for 24 hours revealed that 35-50% of the total 14C fixed appeared in the animal tissue lipid (as 14C-glycerol) and protein. From a comparison with dark controls it is concluded that photosynthetic products of zooxanthellae are translocated to host coral tissue. The skeletal organic matrix also acquires 14C.3. Zooxanthehellae isolated from corals and incubated in a homogenate of host coral tissue selectively release glycerol and traces of other organic material including glucose, alanine, and glycolic acid confirming previous observations.

400 citations


Journal ArticleDOI
TL;DR: A method is described for raising sea urchins from egg to egg in the laboratory and the major features in the developmental process are: growth of the larvae, development of the urchin inside the larva, metamorphosis and growth ofThe young urchine to sexual maturity.
Abstract: A method is described for raising sea urchins from egg to egg in the laboratory. The larvae are raised on flagellated marine algae and the young urchins on a substrate-dwelling diatom. The major features in the developmental process are: growth of the larva, development of the urchin inside the larva, metamorphosis and growth of the young urchin to sexual maturity. The entire life cycle takes about six months.

195 citations


Journal ArticleDOI
TL;DR: The development times to hatching of eggs of eleven species of copepods are closely described as functions of temperature (T) by Bělehrádek's temperature function, D = a (T - α)b using the assumption that the same value of b applies to all species.
Abstract: The development times to hatching (D) of eggs of eleven species of copepods are closely described as functions of temperature (T) by Bělehradek's temperature function, D = a (T - α)b using the assumption that the same value of b applies to all species. The value of a is related to egg diameter among three species of Calanus, and is unaffected by the greater opacity (presumably yolkiness) of eggs of C. hyperboreas. The value of a remains as the "real" indicator of temperature adaptation, and is closely and linearly related to estimates of environmental temperature based on mean annual temperatures within the range of each species between the pole and South America, along the east coast of the Americas.

195 citations


Journal ArticleDOI
TL;DR: The respiratory responses of two mud-shrimps, Callianassa californiensis and Upogebia pugettensis, from Yaquina Bay, Newport, Oregon, were measured.
Abstract: 1. The respiratory responses of two mud-shrimps, Callianassa californiensis and Upogebia pugettensis (Thalassinidea), from Yaquina Bay, Newport, Oregon, were measured.2. Both species are metabolic regulators, showing oxygen-independent respiration above the critical oxygen tension for C. californiensis of 10-20 mm Hg (6.- 12.5% air-saturation) and for U. pugettensis of 45-50 mm Hg (28-31% air-saturation).3. Within the independent range of respiration, C. californiensis has a mean metabolic rate of 0.029 ml O2 x g wet wt-1 x hr-1, which is significantly lower than that of U. pugettensis (0.059 ml O2 x g wet wt-1 x hr-1).4. Heart rates of C. californiensis subjected to diminishing oxygen tensions show a regulatory pattern similar to the metabolic rate, with bradycardia occurring at ca. 27 mm Hg.5. Both species are tolerant to anoxia. C. californiensis survives approximately 5.7 days and U. pugettensis 3.3 days under such conditions.6. Preliminary data suggest that postmolt U. pugettensis do not regulate and...

121 citations


Journal ArticleDOI
TL;DR: It is concluded that the orientation of all fan-shaped sessile organ isms is perpendicular to wave motion and that it may result solely from hydro dynamic phenomena.
Abstract: Sea fans (Gorgonia ventalina and G. flabelluin) grow in patches at depths of 2 to 10 m on the seaward reefs of the Florida Keys. The sea fans in any particular patch appear to have a preferred orientation of their fan “?�blades.” ThA©odorand Denizot ( 1965 ) have noted this phenomenon and concluded from the parallel orien tation of algae and gorgonians that the orientation of all fan-shaped sessile organ isms is perpendicular to wave motion and that it may result solely from hydro dynamic phenomena. We have asked the questions, “?�To what extent do sea fans on Florida reefs show preferred orientation ?“ and “?�What can be inferred from the morphology of the sea fan and from the habitat concerning the mechanism that brings about this orientation ?“ METHODS We worked on several coral reef sites on the upper Florida Keys over July and August, 1966, and put in more than 25 man-hours making observations and photo graphs while using self-contained underwater breathing apparatus. We spent at least one fifth of this time diving through twilight hours and into darkness. We exposed twenty-four 50-foot rolls of Super 8 mm movie film using a Kodak M-6 camera with close-up lenses to record observations and to aid further study of the activities of soft and stony corals. For measurement of the orientation of sea fan blades to points of the compass, a waterproof compass was mounted in the center of a 12” square white plastic board. Holding the board horizontally we then placed a side of the board flat against the blade of a sea fan and made a pencil mark on the board at the north arrow. We measured maximum height and breadth of the fan to ±0.5 cm with a 30 cm rule and recorded these figures next to the orientation mark. We recorded these data for every fan in each patch studied. We surveyed patches in the following places:

119 citations


Journal ArticleDOI
TL;DR: Salinity changes, similar to those occurring with change in tide in the inshore environment usually occupied by pink shrimp, were imposed on both postlarvae and juveniles in a constant-current apparatus.
Abstract: 1. The inshore movements of postlarval pink shrimp and the subsequent offshore movements of the juveniles are facilitated by flood and ebb tides, respectively. This investigation concerns the behavioral mechanisms involved in the selective use of one tide and the evasion of the other.2. Salinity changes, similar to those occurring with change in tide in the inshore environment usually occupied by pink shrimp, were imposed on both postlarvae and juveniles in a constant-current apparatus.3. Juvenile shrimp were almost invariably positively rheotactic. However, with a decrease in salinity the sign of the response was reversed, resulting in active downstream swimming. This often gave way to passive drifting.Under conditions of low light intensity postlarvae were active in the water column, and being unable to withstand even slow currents, were easily displaced. With a decrease in salinity they sank to the substrate or remained low in the water column where they were better able to maintain position.4. Respons...

114 citations


Journal ArticleDOI
TL;DR: Oogenesis in the sea urchin Strongylocentrotus purpuratus was studied by histological methods and by histochemical techniques for polysaccharides, lipids, and nucleic acids to correlate seasonal variations in coastal water temperature with the gonadal cycle.
Abstract: 1. Oogenesis in the sea urchin Strongylocentrotus purpuratus was studied by histological methods and by histochemical techniques for polysaccharides, lipids, and nucleic acids. Urchins were collected at Yaquina Head, Oregon at regular intervals between April 1966 and March 1967. An attempt was made to correlate seasonal variations in coastal water temperature with the gonadal cycle.2. Oogonia can be found throughout the year in small groups scattered along the walls of the ovary, but are most numerous in the late spring and early summer when the ovary is spent. The oocytes start growing in the late summer and early fall when the accessory cells start filling with lipid and polysaccharide globules. At this time the accessory cells are found to have inclusions that appear to be degenerate sex cells. The oocytes continue to grow through the late fall and early winter and their cytoplasm fills with lipid and polysaccharide. As the ova mature they move from the wall to the central portion of the acinus where t...

84 citations


Journal ArticleDOI
TL;DR: Artificial spawning could be induced without using nerve extract; ovarian fragments immersed in Mg-free sea water released their eggs after a certain interval, while those treated with Ca- free sea water for an appropriate period spawn after subsequent addition of calcium.
Abstract: 1. When a water extract of radial nerves of the starfish, Asterias amurensis, was locally applied to one part of an isolated whole ovary for an appropriate period and then small slits were made on the ovarian wall, intense discharge of eggs occurred only in the treated portion.2. Eggs within the nontreated part of the ovary were observed to adhere to each other and to the gonadal wall by means of the follicle layer surrounding them.3. Eggs within ligated ovarian fragments which had been treated with nerve extract lost their follicles and underwent maturation. These eggs were found to be freely movable.4. Artificial spawning could be induced without using nerve extract; ovarian fragments immersed in Mg-free sea water released their eggs after a certain interval, while those treated with Ca-free sea water for an appropriate period spawn after subsequent addition of calcium.5. Breakdown of follicles occurred within an ovary treated with calcium-free sea water.6. Treatment with contraction-inducing agents suc...

82 citations


Journal ArticleDOI
TL;DR: The reactions of specimens of Nassarius obsoletus exposed individually to controlled laboratory stimuli are as follows: Nassarius shows a light-compass reaction, but no optomotor response, and mud snails accumulate on those richest in diatoms and bacteria.
Abstract: The reactions of specimens of Nassarius obsoletus exposed individually to controlled laboratory stimuli are as follows:1. Nassarius shows a light-compass reaction, but no optomotor response.2. On damp slopes Nassarius moves downhill. Submerged Nassarius is generally geonegative but its response is altered by a nearby light source.3. In clean seawater Nassarius moves downstream.4. Addition of effluents from damaged animal tissues or from mud causes a reversal of rheotaxis.5. A small but significant upstreaming response is elicited by water of raised oxygen concentration.6. The upstreaming response to olfactory stimuli can be abolished when unfavorable stimuli (hypo-or hypersalinity) are simultaneously present.7. Water which has passed over living, intact Nassarius is attractive to other individuals of the species Nassarius, the attraction not being due to faeces.8. When simultaneously presented with substrates of different kinds, mud snails accumulate on those richest in diatoms and bacteria.9. The behavio...

79 citations


Journal ArticleDOI
TL;DR: A comparative study has been made of the food, feeding mechanisms, gut structure, digestive physiology and food reserves of representative species from three of the four orders of Rhynchocoela (Anopla and Heteronemertini; Enopla: HoplonemERTini).
Abstract: 1. A comparative study has been made of the food, feeding mechanisms, gut structure, digestive physiology and food reserves of representative species from three of the four orders of Rhynchocoela (Anopla: Palaeonemertini and Heteronemertini; Enopla: Hoplonemertini).2. Polychaete or oligochaete annelids form the staple diet in the Anopla and one species of Enopla. Amphiporus lactifloreus (Enopla) is exceptional in that it feeds exclusively on the amphipod crustacean Gammarus locusta.3. Living prey are captured by means of the proboscis, but inert or dead foods, when taken, are ingested directly without proboscis eversion.4. In the Hoplonemertini the proboscis is armed with stylets and toxic secretions which kill the prey before ingestion, and a forerunner of this system is seen in the Palaeonemertini where minute epithelial barbs perforate the prey's integument to allow entry of paralyzing substances. In the Heteronemertini, though, the prey is swallowed alive and killed by acid secretions in the foregut.5...

77 citations


Journal ArticleDOI
TL;DR: The 1959 undefined artificial medium for Artemia was simplified to a medium containing only defined ingredients: a liquid phase containing mineral salts, 6 amino acids, 5 nucleic acid components, 8 vitamins, 2 sugars, a pH buffer, and a fine particulate phase consisting of precipitated albumin, gelled rice starch, and cholesterol.
Abstract: 1. The 1959 undefined artificial medium for Artemia was simplified to a medium containing only defined ingredients: a liquid phase containing mineral salts, 6 amino acids, 5 nucleic acid components, 8 vitamins, 2 sugars, a pH buffer, and a fine particulate phase consisting of precipitated albumin, gelled rice starch, and cholesterol. The amino acids and sugars are dispensible.2. Starch and albumin were not replaceable by their soluble components (sugar and amino acids) even in the presence of inert or absorbing particles. Phagotrophy appeared the most efficient way to satisfy the bulk nutritional requirements.3. Growth rate and differentiation depended upon starch: protein ratio and total quantity of particles.4. Artemia ingested liquids but apparently to a very limited extent since vitamins and nucleic acid components (nontoxic even at very high concentrations) were utilized as solutes only when in high concentrations. Amino acid mixtures on the other hand became toxic at concentrations too low to satisf...

Journal ArticleDOI
TL;DR: These results, together with earlier findings on regulation of ions and water in Miamiensis avidus, suggest that this organ is regulated by external osmolarity, not ionic strength or concentration of individual ions.
Abstract: 1. The total free amino acid concentration in Miamiensis avidus in 100% sea water is 317 mM/kg cells. Alanine, glycine and proline account for 73% of the total.2. Reducing the external osmolarity resulted in a decrease in intracellular free amino acids; raising the external osmolarity resulted in an increase in free amino acids. At the extreme salinities tested, cells in 25% sea water contained 24% of the free amino acids of cells in 100% sea water; cells in 200% sea water had a 22% greater free amino acid content than cells in 100% sea water. All of the changes were complete 20 minutes after the salinity changes.3. The intracellular free amino acid content was a function of external osmolarity, and not ionic strength or concentration of individual ions.4. The mechanism of the increase in free amino acid content was mobilization of bound amino acids, and not uptake from the medium.5. These results, together with earlier findings on regulation of ions and water in Miamiensis avidus, suggest that this organ...

Journal ArticleDOI
TL;DR: These experiments examined the mechanism whereby regeneration delays development and molting in the waxmoth, Galleria mellonella, and also the possible role of the molting hormone in controlling regeneration.
Abstract: 1. These experiments examined the mechanism whereby regeneration delays development and molting in the waxmoth, Galleria mellonella, and also the possible role of the molting hormone in controlling regeneration.2. Removal of one or more imaginal wing discs from four-day old last instar larvae delayed the further development of unoperated discs and the pupal molt, confirming prior observations on Ephestia, Blattella and Periplaneta by other workers. The delay in molting was proportional to the amount of regenerating tissue: extirpation of one wing disc caused a five-day delay, whereas extirpation of all four discs caused a 14-day delay. When time regenerating epithelium was destroyed by cautery, no delay in molting occurred. Several possible mechanisms for this delay were examined.3. In another series of experiments four-day old last instar larvae were ligated in such a way as to eliminate both brain and prothoracic glands. When imaginal wing discs were extirpated from these ligated larvae 0 to 14 days aft...

Journal ArticleDOI
TL;DR: Growth of larvae was most rapid within the salinity range from 20 to 35‰ and within the temperature range from 22.5 to 27.5° C and atSalinity and temperature were significantly related only when the tolerance of either one or the other was approached and, conversely, when both salinity andTemperature were within the satisfactory range there was no significant interrelationship.
Abstract: 1. Embryos of M. lateralis held at 25 ± 1° C developed satisfactorily (70% or more of maximum) within the salinity range from 22.5 to 30‰; 27.57‰ was optimum. Some embryos developed normally, however, at salinities as low as 15‰ (10%) and as high as 37.5‰ (1.2%). 2. Some larvae survived at all salinities tested (7.5 to 37.5‰); survival was 70% or more only within the range from 20 to 27.5‰. 3. Larvae grew satisfactorily within the salinity range from 20 to 30 or 32.5‰; 25‰ was optimum. 4. Embryos held at 27 ± 0.5‰ salinity developed satisfactorily within the temperature range from 15 to 25° C; 20° C was optimum. Some embryos developed normally, however, at temperatures as low as 10 (17.3%) and as high as 30° C (39%). 5. Some larvae survived at temperatures from 7.5 (lowest tested) to 32.5° C; survival was satisfactory from 7.5 to 27.5° C. 6. Larvae grew satisfactorily at temperatures from 20 to 30° C; 27.5° C was optimum. 7. The effects of salinity and temperature were significantly related only when the tolerance of either one or the other was approached. When the salinity was unfavorable, the range of temperature was markedly narrowed and, conversely, when both salinity and temperature were within the satisfactory range there was no significant interrelationship. 8. The range of temperature tolerance for embryos narrowed above and below 30‰ salinity, and salinity tolerance narrowed above and below 22.5° C. 9. Survival of larvae was relative uniform at temperatures of 7.5 to 27.5° C and at salinities from 10 to 35‰, but at 32.5° C (at all salinities other than 30‰) the percentage of larvae surviving was drastically reduced. 10. Growth of larvae was most rapid within the salinity range from 20 to 35‰ and within the temperature range from 22.5 to 27.5° C.

Journal ArticleDOI
TL;DR: The 5-day reproductive cycle of Periplaneta is continuous with an ootheca being formed every fifth day, and changes in blood volume occur during the cycle, and these changes amplify rather than diminish the blood protein fluctuations.
Abstract: 1. The 5-day reproductive cycle of Periplaneta is continuous with an ootheca being formed every fifth day. The rate of yolk formation is lowest during ootheca formation(day 1) and reaches a peak during days 3 and 4.2. Vitellogenic blood protein levels fluctuate between 1 and 6 µg/µl and their concentrations correlate with the rate of yolk formation. The two vitellogenins oscillate synchronously during the cycle.3. The total blood protein concentration increases to 80 µg/µl on day 5, decreases abruptly to 52 µg/µl when ootheca formation is initiated, and increases gradually to the concentration peak on day 5. The changes in total blood protein concentration are not obviously correlated with the vitellogenic cycle.4. Changes in blood volume occur during the cycle, and these changes amplify rather than diminish the blood protein fluctuations.5. A hiatus in food consumption is observed during ootheca formation; feeding is resumed after the third day following oviposition.

Journal ArticleDOI
TL;DR: The reproductive polymorphism in Daphnia pulex may be under the control of photoperiod and a second stimulus whose effect is proportional to culture density, which is tested with a monocyclic strain and extended to describe control in two other strains of D. pulesx.
Abstract: The reproductive polymorphism in Daphnia pulex may be under the control of photoperiod and a second stimulus whose effect is proportional to culture density. Originally tested with a monocyclic strain, the hypothesis is extended to describe control in two other strains of D. pulex.The dicyclic strain which displays the polymorphism in both long and short-day photoperiod ls may be only short-day inductive by usual standards. Long-day expression results when photoperiod control is thermally uncoupled. Display of the polymorphism is then under the control of culture density.The acyclic strain, which in nature omits the reproductive polymorphism, may be induced in the laboratory. It is the acyclic strain which demonstrates the simultaneous requirement of inductively short photoperiod and the density proportional stimulus. The three types of seasonal cycles in D. pulex are presumed to be genetically distinct responses to the two control stimuli. The dicyclic strain may be the most sensitive to thermal uncoupli...

Journal ArticleDOI
TL;DR: Control of the sexual polymorphism leading to an embryonic diapause was studied in an arctic population of Daphnia middendorffiana, finding that control may be partially overridden in long days (constant light) by density of culture.
Abstract: 1. Control of the sexual polymorphism leading to an embryonic diapause was studied in an arctic (71° N) population of Daphnia middendorffiana. The reproductive cycle is similar to a previously analyzed population of D. pulex although males are non-functional in the polymorphism.2. In constant temperatures and standardized culture density the reproductive shift is controlled by daylength with a critical photoperiod of L:D 22:2 at 12° C. Control may be partially overridden in long days (constant light) by density of culture. The overwintering generation shows resistance to both photoperiodic induction and density suppression, and one or two non-diapause broods are released before reproduction shifts.3. The reproductive shift in the source pool at Barrow, Alaska occurs in mid-July when the sun is continuously above the horizon and after the overwintering generation has released one brood of non-diapausing embryos. Completeness of the shift and the relatively low density of the population in the pool argues a...

Journal ArticleDOI
TL;DR: The effects of colchicine were studied on pigment migration in melanophores of the killifish, Fundulus heteroclitus and the mechanism of action is unclear but is discussed in relation to possible effects on cytoplasmic viscosity and microtubules.
Abstract: Previous work has shown that colchicine has an effect on the movement of melanin granules in the melanophores of isolated frog skin. Thus pretreatment of frog skin with colchicine enhances the darkening produced by melanocyte-stimulating hormone (MSH) (Malawista, 1965) and inhibits the lightening which follows upon the removal of MSH (Wright, 1955; Malawista, 1965). Colchicine has also been found to inhibit the aggregation of pigment in tissue cultured melanophores of Xenopus laevis after removal of MSH (Kulemann, 1960). The proposal has been advanced that in frog melanophores this drug has an effect on cytoplasmic viscosity (Malawista, 1965; Malawista, Asterita, and Marsland, 1966). Recently Bikle, Tilney and Porter (1966) have shown that an ordered array of microtubules is present in the branching processes of the melanophores of the killifish, Fundulus heteroclitus. These observations have been confirmed by Novales

Journal ArticleDOI
TL;DR: Upogebia pugettensis has a discrete, open and durable burrow system and is distributed further up the Yaquina estuary than is C. californiensis, which is without such a burrows, and Callianassa filholi is strong hyper-osmotic regulators below 75% SW.
Abstract: 1 Callianassa californiensis and Upogebia pugettensis (Crustacea: Thalassinidea) have been studied with respect to their osmoregulatory capacities and selected aspects of their natural history Upogebia affinis and Callianassa filholi have been studied with respect to their osmoregulatory capacities2 Upogebia pugettensis has a discrete, open and durable burrow system and is distributed further up the Yaquina estuary than is C californiensis, which is without such a burrow system3 Resident species of thalassinids are exposed to brackish conditions in the winter and spring at Yaquina Bay4 The lower lethal salinity limit for U pugettensis and U affinis is approximately 10% SW; that for C californiensis is 25%-30% SW; that for C filholi is probably 35%-40% SW5 U pugettensis and U affinis are strong hyper-osmotic regulators below 75% SW In full strength SW, U pugettensis and U affinis are iso-osmotic, and the former species conforms osmotically in 125% SW In U pugettensis the ions of Na+,

Journal ArticleDOI
TL;DR: Although the male of Nasonia vitripennis is distinctly smaller than the female, the antennae are approximately the same size in both sexes.
Abstract: 1. Although the male of Nasonia vitripennis is distinctly smaller than the female, the antennae are approximately the same size in both sexes.2. Hairs of two kinds, both believed to be tactile, are present on the antennae of both males and females. One type is found only on the twelfth subsegment.3. Chemoreceptors of three kinds—thick-walled pegs, thin-walled pegs and plate organs—occur on the antennal flagellum of both sexes.4. Thick-walled pegs are restricted to the eleventh and twelfth subsegments of the antenna. Elsewhere on the body they were found on the terminal segments of the maxillary and labial palps and on the tarsal claws.5. Thin-walled pegs are present in large numbers on all subsegments from the third to the eleventh.6. Plate organs occur on all subsegments from the third to the eleventh. A mean number of 43 plate organs was found on the antenna of the male and 81 on the antenna of the female. The entire outer surface of the plate is perforated by a large number of very small openings.

Journal ArticleDOI
TL;DR: The growth and reproductive biology of the adult female stone crab, Menippe mercenaria, an economically important species in Florida, have never been investigated in the laboratory and the relation between these processes, their endocrine control, and the changing environmental conditions provided in nature is surveyed.
Abstract: The growth and reproductive biology of the adult female stone crab, Menippe mercenaria, an economically important species in Florida, have never been investigated in the laboratory. These morphogenetic processes are influenced both by hormones and by seasonal changes in the environment. This study seeks to survey the relation between these processes, their endocrine control, and the changing environmental conditions provided in nature. Special attention has been paid to the interrelationship between growth and reproduction. This aspect has been studied by Bauchau (1961), Cheung (1966) and DA©meusy(1964, 1965a, 1965b and 1965c) in Carcinus mcienas, a boreal species. The present study employs adult female specimens of M. mercenaria since they continue to grow after reach ing sexual maturity, unlike Callinectes in which growth ceases at maturity (Truitt, 1939). The relationship between growth and reproduction was defined by (1) observ ing the occurrence of molting and spawning in a sample of the wild population; and (2) removing the eyestalks at different stages of the molting cycles and during intermolt periods occurring at different times of the year, because the eyestalks contained endocrine factors regulating these processes. Results of this study also yielded information on the life history of this species. MATERIALS AND METHODS

Journal ArticleDOI
TL;DR: Two species of algae were living symbiotically with a hard brain coral, Fa@ia, harvested in the environs of the Flinders Island Group on the Great Barrier Reef in Australia, and their in vivo absorption spectra as well as the spectral distribution were described.
Abstract: Two species of algae were living symbiotically with a hard brain coral, Fa@ia, harvested in the environs of the Flinders Island Group on the Great Barrier Reef in Australia. One of the algae has the microscopic appearance and pigment corn position of dinoflagellates (Halldal, 1968, Jeffrey and Haxo, 1968) and it contrib utes the dark brown color to the coral tissues which form a surface layer over the colony. This alga resembles Symbiodiniuni microadriaticum Freudenthal. Green algae lived inside the spherical coral forming another colored layer (Jeffrey, 1968) , and there was an intermediate pale green (nearly white) layer between these brown and green layers. The green algae seemed to be of mixed genera and species, most of them probably belonging to Ostreobiuni Reineckei Bornet within the order Siphonales. The present paper describes the in vivo absorption spectra of these algal layers as well as the spectral distribution. EXPERIMENTAL METHODS The samples of Favia pallida DaIla were harvested in the environs of the Flinders Island Group, and were kept in running sea-water aquaria on the open deck of the research vessel. The spectral data presented in this paper were observed for the sample which was 12 cm in diameter and 8.5 cm in thickness

Journal ArticleDOI
TL;DR: A shift in the major developmental stimulus from long day during the winter to food after prolonged chilling in the laboratory was observed and is hypothesized to be an adaptation to life in shallow ponds in temperate climatic regions.
Abstract: 1. The termination of larval diapause in C. americanus is cued by simultaneous long day and food.2. One long day cycle with food elicits development in a significant proportion of the population.3. A shift in the major developmental stimulus from long day during the winter to food after prolonged chilling in the laboratory was observed and is hypothesized to be an adaptation to life in shallow ponds in temperate climatic regions.4. The action of food may occur via the ventral abdominal nervous system as described by Fuller (1960) with ultimate neuro-endocrine control of development residing in the brain.

Journal ArticleDOI
TL;DR: Data suggest that visual form discrimination in bats such as Anoura geoffroyi is comparable or superior to that demonstrated in pigmented laboratory rats.
Abstract: Two species of echolocating Microchiroptera were behaviorally conditioned to visually discriminate between various pairs of simple, equal area patterns presented simultaneously as silhouettes against a diffusely trans-illuminated background. These were Carollia perspicillata (frugivouous) and Anoura geoffroyi (nectivorous). Data suggest that visual form discrimination in bats such as Anoura geoffroyi is comparable or superior to that demonstrated in pigmented laboratory rats. Pattern vision may supplement or replace acoustic orientation in the detection of relatively large distant objects where the propagation losses of ultrasonic cries seriously reduce the echo intensity. Vision may be an important aid to navigation of bats on feeding or migratory flights.

Journal ArticleDOI
TL;DR: Echinaster echinophorus possesses a digestive system very similar to that of Henricia, and Tracer experiments demonstrate that various dissolved amino acids, glucose, and possibly proteins are taken up continually by the exposed superficial tissues of the body.
Abstract: 1. Echinaster echinophorus possesses a digestive system very similar to that of Henricia. Its Tiedemann's pouches are well developed and appear to function as pump organs.2. About one third of the specimens seen in the field are found in a feeding posture on sponges (even though the sponges do not appear to be greatly harmed). Occasionally specimens are also found with everted stomachs on sand, algae, ascidians, molluscs, and other organisms. Captive specimens will assume a feeding position on opened clams and other defenseless invertebrates, but rarely completely devour them.3. Tracer experiments demonstrate that various dissolved amino acids, glucose, and possibly proteins are taken up continually by the exposed superficial tissues of the body. If present in suitable concentration (usually about 25 mg%) most of these substances will also be taken up into the internal digestive organs, presumably because they stimulate the animals to engage in filter-pumping.4. Of the substances that have been studied, g...

Journal ArticleDOI
TL;DR: Within the freedom of movement provided by the basal artery, cavernous body and secondary lamella, blood is free to follow the line of le...
Abstract: 1 The course of blood through the gills is described2 Blood passes first into arteries which parallel the filaments and lie at their base3 Blood then passes into the overlying parallel cavernous bodies through any of the approximately 20 openings per millimeter4 The cavernous bodies have non-elastic walls and, passing across the lumen, non-elastic columns Blood is free to flow in any direction through the cavernous bodies Each cavernous body has approximately 20 pairs of exits per millimeter, each one opening into a secondary lamella5 The secondary lamella does not contain capillaries, but consists of two sheets of epithelium held together, with a constant space between them, by large numbers of pilaster cells Within the single plane of this structure blood is free to move in a variety of directions between its entrance and its exit into the distal artery6 Within the freedom of movement provided by the basal artery, cavernous body and secondary lamella, blood is free to follow the line of le

Journal ArticleDOI
TL;DR: It is suggested that larvae be reared to setting size at temperatures from 25° to 27.5° C, then kept at 20° to 22.5 °C during setting to obtain fastest growth of larvae and highest percentage setting.
Abstract: 1. The temperature range for satisfactory growth of O. edulis larvae (70% or more of optimum) was from 17.5° to 30° C.2. The temperature range for satisfactory survival (70% or more of optimum) was from 12.5° to 27.5° C. Even at 10° and 30° C survival was poor, perhaps, because the unfavorable temperatures weakened the larvae, making them more susceptible to bacterial toxins and diseases.3. In these experiments approximate setting times were as follows: 17.5° C—26 days, 20° C—14 days, and at 25°, 27.5°, and 30° C beginning of setting varied from the 8th to the 12th days.4. More spat were obtained at 20° to 22.5° C than at higher temperatures.5. It is suggested that larvae be reared to setting size at temperatures from 25° to 27.5° C, then kept at 20° to 22.5° C during setting to obtain fastest growth of larvae and highest percentage setting.6. Spat kept at 10° C showed virtually no growth; at temperatures from 12.5° to 27.5° C growth of spat increased with each increase in temperature.

Journal ArticleDOI
TL;DR: In the case of the circadian rhythm of adult emergence in Drosophila pseudoobscura, a distinction between these two interpretations of arhythmicity is made possible by comparing the rhythm-phase shifting and rhythm-inducing effect of the same temperature signal.
Abstract: 1. Although circadian rhythms are systematically and physiologically ubiquitous in eucaryotic organisms, they are not evident under certain experimental conditions. For example, there is no circadian rhythm in adult emergence in populations of Drosophila pseudoobscura if the organism is raised in constant dark and temperature.2. In general, such overt arhythmicity could be interpreted as due to asynchrony or true arhythmicity of constituent parts (organelles in cells; cells and organs in individuals; individuals in populations).3. In the case of the circadian rhythm of adult emergence in Drosophila pseudoobscura, a distinction between these two interpretations of arhythmicity is made possible by comparing the rhythm-phase shifting and rhythm-inducing effect of the same temperature signal. It was concluded that arhythmicity of Drosophila populations was due to a true arhythmicity of constituent parts (individual flies).4. Other experiments are mentioned in which the arhythmicity of populations and individu...

Journal ArticleDOI
TL;DR: The histological characteristics of the cement apparatus of barnacles have been compared in Lepas anatifera and Balanus tintinnabulum and may indicate differences in the secretory mechanisms.
Abstract: 1. The histological characteristics of the cement apparatus of barnacles have been compared in Lepas anatifera and Balanus tintinnabulum.2. In both species the cement is formed in unicellular glands and conducted to the points of attachment through a series of tubular canals.3. The cement gland cells of L. anatifera differ from those of B. tintinnabulum in several cytological details which may indicate differences in the secretory mechanisms.

Journal ArticleDOI
TL;DR: The digenetic trematode described by Linton (1900) as Distoma pyriforme has been reported from many hosts and several species have been included in the accounts, with resultant confusion.
Abstract: The digenetic trematode described by Linton (1900) as Distoma pyriforme has been reported from many hosts and several species have been included in the accounts, with resultant confusion. It was included in the genus Lepocreadium Stossich, 1904 by Linton (1940), but it is not congeneric with L. album (Stossich, 1890), type of the genus. Its life-cycle has been elucidated; Anachis avara is the first intermediate host, where cercariae are produced in rediae. The cercariae are ophthalmotrichocercous, swim actively with the tail in advance. They penetrate but do not encyst in certain hydrozoan and scyphozoan medusae and in the ctenophore, Mnemiopsis leidyi. Developmental and adult stages resulted from ingestion of metaceracariae by the scup, Stenotomus chrysops. Eggs from worms were embryonated; miracidia emerged in 8 to 10 days, penetrated into A. avara, transformed into sporocysts, and produced rediae in 5-6 weeks. Worms recovered from S. chrysops are assigned to a new genus, Neopechona, and redescribed as ...