Showing papers in "The Biological Bulletin in 1970"
TL;DR: Particles in the 1.0 to 3.0 µ range may play an important role in the nutrition of oysters and other lamellibranchs and their removal by these organisms may also be an important factor in sedimentary processes.
Abstract: 1. Particle filtration by the oyster Crassostrea virginica was studied in the 1.0 to 12.0 µ size range in relation to naturally occurring particles and to kaolinite suspensions in filtered river water. 2. Oysters were held in troughs of flowing water under conditions similar to their natural environment. Particle number and volumes entering and leaving the troughs were enumerated using a Coulter electronic particle counter. Particle diameter was expressed as that of a sphere having a volume equal to the particle. 3. Results of the study were expressed as per cent of total particles removed in various size increments or in volumes removed over the same size range. 4. Oysters filtered naturally occurring particles in the 1.0 to 3.0 µ range with about one-third the efficiency as larger particles. Above 3.0 µ there was no change in efficiency with increasing particle size. For kaolinite particles, oysters removed particles in the 1.0 to 2.0 µ range with about half the efficiency as larger particles. Above this size there was no change. 5. When results are expressed in terms of per cent removal, the importance of the small sized particles is minimized. In terms of volume, particles in the 1.0 to 3.0 µ range constitute the largest single size fraction over the 1.0 to 12.0 µ range. 6. The consistent presence of an inflection point at a particle size around 2.0- 3.0 µ in the curve for per cent removed vs. particle size is an indication that the distance between adjacent latero-frontal cilia is the factor that determines the smallest particle size that can be completely retained by the oyster gill. 7. Presence of the inflection point is also interpreted as negating the existence of a mucous sheet over the gills, as suggested by MacGinitie (1941). 8. Particles in the 1.0 to 3.0 µ range may play an important role in the nutrition of oysters and other lamellibranchs. Their removal by these organisms may also be an important factor in sedimentary processes.
143 citations
TL;DR: Histological and autoradiographic studies revealed that ecdysterone at the levels used in these experiments caused molting in crayfish without DNA replication.
Abstract: 1 The ability of ecdysones to induce molting in arthropods other than insects was examined in representatives of both the mandibulate and chelicerate subphyla2 All five ecdysones tested caused molting in the fresh-water crayfish, Procambarus Their relative activities were: ecdysterone > inokosterone > α ecdysone > ponasterone A > cyasterone Doses as low as 3 µg/g of ecdysterone caused 100% of all test crayfish to undergo apolysis and secrete a new cuticle within 14 days after injection, but only in a few cases did the animals shed their old cuticles spontaneously after experimental treatment At higher doses the new cuticle was thinner than normal and had abnormal bristles The stimulation of molting was specific for ecdysones and was not copied by a variety of ecdysone analogues or other steroids3 Histological and autoradiographic studies revealed that ecdysterone at the levels used in these experiments caused molting in crayfish without DNA replication4 Ecdysterone also caused molting in the ma
98 citations
TL;DR: First morphological blood cell types are recognized in Halocynthia aurantium and there is no significant difference in total blood cell concentration per cubic millimeter of blood as a function of weight of animal.
Abstract: 1. Then morphological blood cell types are recognized in Halocynthia aurantium. The mature morula cells, dispersed vesicular cells, stem cells, and stem cells with acidophilic vacuoles or granules decrease in differential distribution with increased weight of animal. The hyaline amoebocyte increases in differential distribution with increased weight of animal.2. There is no significant difference in total blood cell concentration per cubic millimeter of blood as a function of weight of animal.3. The mature morula cells, dispersed vesicular cells, hyaline amoebocytes, and granular amoebocytes are at significantly higher concentrations in the tunic of the body wall and stolon than they are in the blood. The mature morula cell is concentrated in the tunic just peripheral to the epidermis and the dispersed vesicular cell is concentrated at the external limits of the tunic. The hyaline amoebocyte is a phagocyte.4. Upon injury to the tunic, the mature morula cells and dispersed vesicular cells increase signific...
96 citations
TL;DR: The reproductive physiological variation in the populations of scallops may have been favored through selection as an adaptive response to the geographical differences in temperature and time of abundant food production.
Abstract: 1. The geographically separated populations of the bay scallop A. irradians from Woods Hole, Massachusetts, and Beaufort, North Carolina, vary in their timing of reproductive events. These events occur earlier in the year at Woods Hole than at Beaufort.2. The monthly gonad index values of the populations are fitted with three-term Fourier curves to show the cyclical trend of gonad activity response within the year. Periodic regression analysis of the data indicates that displacement of maximum gonad response is a significant difference between the two populations.3. The reproductive physiological variation in the populations of scallops may have been favored through selection as an adaptive response to the geographical differences in temperature and time of abundant food production.4. The variation could be either phenotypic or truly genetic.
93 citations
TL;DR: Barnacles, which become partially or totally detached from their substratum in a natural environment, produce a secondary cement secretion and laboratory experiments demonstrate that the secondary cement can successfully reattach the barnacle to a new substratum, suggesting that the cement hardening is initiated inside the organism.
Abstract: Barnacles, which become partially or totally detached from their substratum in a natural environment, produce a secondary cement secretion. Laboratory experiments demonstrate that the secondary cement can successfully reattach the barnacle to a new substratum. Similar secondary secretion was found at the site of minor injuries to the barnacle basis. The secondary cement usually has a looser, more cavernous structure than the primary cement, but both secretions have similar staining characteristics. Microscope preparations indicate that occasionally barnacles are capable of developing new secondary cement ducts leading into the injured or detached areas to secrete secondary cement. In most cases, however, the existing primary cement duct network is used for the secondary secretion. This is possible only because most of the once used ducts are not plugged by hardened cement, in spite of the fact that the cement can harden inside the ducts. Chemical analysis suggests that the cement is an organic biopolymer and indications are that the cement hardening is initiated inside the organism. A unique flushing mechanism seems to be responsible for keeping the cement ducts open and ready for reuse. A nonhardening flushing fluid forces the still liquid cement out of the ducts. The cement hardens outside the duct openings sealing the flushing fluid inside the duct network. In case of detachment or injury. the cement seal breaks; the flushing fluid drains out leaving the duct open for the secondary cement secretion. The vesicles in conjunction with the main channel control the flow of the flushing fluid and the cement. The permeable wall of the main channel portion inside the vesicle reduces the convection and diffusion between the vesicle and the main channel, thus bypassing of vesicles and duct networks not affected by detachment is possible. The wall of the main channel inside the vesicle is also collapsible, thus acting as checkvalve when the vesicle is under pressure and allowing the cement to be pumped only into the ducts toward the secretory orifices.
83 citations
TL;DR: The katydid, Neoconocephalus robustus, produces a continuous song by rubbing its forewings together at frequencies of 150-200 per second, the temperature gradient being greater the lower the ambient temperature.
Abstract: 1. The katydid, Neoconocephalus robustus, produces a continuous song by rubbing its forewings together at frequencies of 150-200 per second. During singing the thoracic temperature is 5-15° C higher that that of the environment, the temperature gradient being greater the lower the ambient temperature.2. Singing is preceded by a warm-up period during which normally antagonistic forewing muscles contract synchronously. The result is heat production and a rising thoracic temperature (1.5° C/min) with little overt movement.3. The thoracic temperature at the onset of singing averages 33.5° C at ambient temperatures at 23.5°-29° C.4. The rate of heat loss at the cessation of singing indicates that the animal must produce 0.5 cal/min (3.6 cal/min/g thorax weight) to maintain a 15° C temperature gradient.5. This insect is immobilized by cooling to 11° C, but regains mobility when rewarmed to 21.5° C. It is reversibly immobilized at thoracic temperatures above 43.9° C.6. N. robustus basks readily, but moves to sha...
75 citations
TL;DR: The calculated net diffusional (osmotic) water influx is adequate to account for the urine production of Carcinus in 50-70% SW, but does not account for urine production in SW, and it seems necessary to postulate some isotonic transport of water.
Abstract: 1. The apparent water-permeability of Carcinus maenas, as measured by D2O influx, is 2-3 times higher than that of the more euryhaline crab Rhithropanopeus. 2. Like Rhithropanopeus, Carcinus shows a reduction of water-exchange rate at lower salinities. The highest hourly water-exchange fraction is in 75% SW (K = 2.73), the lowest in 30% SW (K = 1.76); values refer to a crab with wet weight of 10 g, at 18° C. 3. The calculated net diffusional (osmotic) water influx is adequate to account for the urine production of Carcinus in 50-70% SW, but does not account for urine production in SW, and only inadequately for the urine produced in 30-40% SW, and it seems necessary to postulate some isotonic transport of water.
73 citations
TL;DR: Liinulus polyphensus is one of the four living species of horseshoe .crabs, a group with a geological history which can be traced back to the Silurian and even to the Cambrian.
Abstract: Liinulus polyphensus is one of the four living species of horseshoe .crabs, a. group with a geological history which can be traced back to the Silurian (Neolimu lus) and even to the Cambrian ( StA˜rmer, 1952) . The Mesozoic species originally referred to the genus Liniulus are closely related and similar to present-day forms and Mesolinzulus walchi of the Jurassic Solnhofen lagoons co-existed with a fauna which included jelly-fishes, swimming crinoids and ammonites (Abel, 1927). During the intervening 135 million years (Howarth, 1964) the xiphosurans of the lagoons and seas covering parts of Germany, France, England, Sweden and N. Africa have disappeared leaving three living genera, one on the east coast of North America (Liniulus) , and the other two on the south-east and east coasts of Asia
73 citations
TL;DR: The coelomic fluid of PW-adapted worms is electronegative by 12 to 30 mV relative to the bath, and excretion of these compounds is probably through nephridia so that this is a maximum estimate of the rate of urine excretion.
Abstract: 1. Earthworms maintain a hyperionic steady state while living in a dilute solution containing Na+, K+, Ca+2, Cl- and HCO3-(PW).2. The inside (coelomic fluid) of worms is electronegative by 12 to 30 mV relative to the bath (PW).3. Sodium and chloride are transported across the skin against an electrochemical gradient. Each ion may be transported independently of the other presumably in exchange for an endogenous ion of like charge.4. For animals in PW, Cl- is exchanged at a rate of 0.9 µeq/10g-hr and Na+ at a rate of 0.3 µeq/10g-hr. The influx of Na+ is dependent on Na+ concentration in the bath and displays saturation kinetics (Vmax= 1 µeq/10 g-hr; Ks = 1.3 mMoles/l). Chloride kinetics were not analyzed.5. Salt depletion increases the influx of Na+ and C1- causing a net uptake of each ion.6. Inulin and dextran are cleared from the coelomic fluid of PW-adapted worms at a rate of 75 µl/10 g-hr. Excretion of these compounds is probably through nephridia so that this is a maximum estimate of the rate of urine...
67 citations
TL;DR: The CONA-induced isoagglutinations of both gamete types, the immobilization, and the unilateral blocking of one mating-type activity can be reversed entirely by mannose.
Abstract: Concanavalin A (CONA) isoagglutinates the gametes within each sex of Chlamydomonas eugametos. C. moewusii syngen I, and C. moewusii syngen II by a typical agglutinative adhesion of the flagella tips. Incubation of gametes with lower CONA-concentrations which do no longer cause isoagglutination, effects blockage of the mating-type activity in only one of the two sexes, the other one being unaffected. In the three taxons investigated, it is always the androgametes which are sensitive to CONA. In addition, CONA immobilizes the cells after a short period of time. The CONA-induced isoagglutinations of both gamete types, the immobilization, and the unilateral blocking of one mating-type activity can be reversed entirely by mannose. In the three taxons, the unilateral sensitivity of the mating-type reaction to CONA is reciprocal to a unilateral sensitivity to 0.1% trypsin. Gynogametes, sexually inactivated by trypsin, still interact with CONA. In each of the three taxons, CONA precipitates both sexual isoaggluti...
63 citations
TL;DR: The distribution of inulin, water, and α-ecdysone was studied in pupae of the silkworm Antheraea polyphemus and there is no evidence that ecdysone is accumulated by any one tissue or excretory organ.
Abstract: 1. The distribution of inulin, water, and α-ecdysone was studied in pupae of the silkworm Antheraea polyphemus. All three compounds reach equilibrium within two hours after injection.2. Inulin is restricted to the extracellular space, which amounts to 0.49 ml per g live weight.3. The ecdysone space is slightly larger than the water space. About 50% of the radioactivity derived from α-ecdysone remains in the blood for at least 36 hours.4. The other 50% is associated with cells in a form which cannot be removed by extensive washing of the intact tissues with saline.5. Transport of ecdysone to the tissues does not involve a rate-limiting carrier system that can be saturated by 10 µg α-ecdysone or 100 µg β-ecdysone.6. There is no evidence that ecdysone is accumulated by any one tissue or excretory organ.7. The metabolism of α-ecdysone was studied by thin layer chromatography of extracts of blood after injection of radioactive α-ecdysone. α-ecdysone is rapidly converted to β-ecdysone and the latter to several ...
TL;DR: This study was undertaken to ascertain the histochemical composition of the tunic, epidermis, and blood cells involved in the Tunic of H. aurantiuni in order to clarify the origin of tunic and the function of the blood cells in thetunic.
Abstract: In the first paper of this series ( Smith, 1969) , the morphology of the tunic and blood cells of the ascidian Ha!ocynthia aurantiu@n ( Pallas) was described. Of the ten blood cell types recognized in this species, four are involved in the tunic : the mature morula cell, the dispersed vesicular cell, the hyaline amoebocyte, and the granular amoebocyte. The mature morula cell and dispersed vesicular cell appear to be intimately involved with tunic growth and repair. The hyaline amoebocyte is a phagocyte. Suggestions have been made concerning the function of these blood cell types in the tunic and their interrelationships based on quantitative considerations of the distribution of these cells within and between animals. It has been suggested that blood cells can secrete tunic (Herdman, 1899 ; Ries, 1937; Endean, 1955a, 1955b, 1960, and 1961), or that blood cells have an organi zational, rather than secretory, function in the tunic ( St. Hilaire, 1931 ; Das, 1936), or that the tunic is secreted primarily by the epidermis ( Deck, Hay and Revel, 1966). There have been numerous reports of the presence of cellulose in ascidian tunic (reviewed by Seeliger and Hartnieyer, 1911 ; Spence and Richards, 1940; Tsuchiya and Suzuki, 1963) and more recently acid mucopolysaccharides and protein have been reported ( Hall and SaxI, 1960 and 1961 ; Bierbauer and Vagas, 1962;Godeaux,1963). Many of the suggestions for the origin of the tunic are based on histocheniical analogy between the tunic and epidermis or tunic and blood cells. There is reason to doubt the specificity of the histochemical and fixation methods of some of the older work in light of recent reports on the nature and specificity of particular histochemical methods (Hale, 1957; Curran, 1961; Quintarelli, 1968). This study was undertaken to ascertain the histochemical composition of the tunic, epidermis, and blood cells involved in the tunic of H. aurantiuni in order to clarify the origin of tunic and the function of the blood cells in the tunic. MATERIALS AND METHODS
TL;DR: The complete medium is superior for all but Scapholeberis mucronata and markedly increases the lifespan and fertility of Moina macrocopa.
Abstract: Fourteen species of the family Daphnidae have been established under continuous monoxenic cultivation utilizing Chlamydomonas reinhardii as sole food organism in a medium consisting of calcium acetate, antibiotics, albumin, trace elements and the water soluble vitamins, folic acid, B12, calcium pantothenate, choline, pyridoxal, inositol, thiamin, nicotinamide, riboflavin, biotin and putrescine. The Daphnidae under cultivation include Daphnia magna, D. pulex, D. galeata mendotae, D. laevis, D. dubia, D. retrocurva, D. parvula, D. ambigua, D. catawba, Moina macrocopa Scapholeberis mucronata, Simocephalus serrulatus, Ceriodaphnia reticulata, and C. quadrangula. The requirements for vitamins for some species are more complex than for others. The complete medium is superior for all but Scapholeberis mucronata and markedly increases the lifespan and fertility of Moina macrocopa.
TL;DR: The limited feeding of Urosalpinx cinerea and Eupleura caudata at 12.5‰ indicates that this salinity is near the lower limit for feeding, and U. cinerca is the more important of the two species as a predator of Crassostrea virginica.
Abstract: 1. At all temperatures studied the limited feeding of Urosalpinx cinerea and Eupleura caudata at 12.5‰ indicates that this salinity is near the lower limit for feeding.2. The feeding rates increased with each increase in temperature and salinity.3. The maximum feeding rates were at the highest temperature-salinity combination studied (25° C, 26.5‰).4. At all temperature and salinity combinations U. cinerea consumed more oyster spat than did E. caudata. Given equal populations, therefore, U. cinerea is the more important of the two species as a predator of Crassostrea virginica.5. Both species of drills exhibited cannibalism in the presence of alternative food sources, but E. caudata did so to a greater extent than U. cinerca.6. Cannibalism increased as the feeding rate increased, and the highest incidence of cannibalism was at optimum feeding conditions.7. In all instances of cannibalism the predators were female drills.8. The mortality rates of both species of drills increased with increasing temperature...
TL;DR: 1. Daphnia magna can be grown for at least 200 generations, axenically or in crude cultures, in a defined mineral medium, enriched with vitamin B12 and thiamine and 1 ml/100 of a dilute organic medium, when fed with Chlamydomonas reinhardi and Scenedesmus obliquus.
Abstract: 1. Daphnia magna can be grown for at least 200 generations, axenically or in crude cultures, in a defined mineral medium, enriched with vitamin B12 and thiamine and 1 ml/100 of a dilute organic medium, when fed with Chlamydomonas reinhardi and Scenedesmus obliquus.2. The organic enrichment is essential for maintaining continued fertility of D. magna.3. The organic enrichment can be replaced by the addition of pantothenic acid to vitamin B12 and thiamine without lowering the fertility of D. magna.4. The organic enrichment (or the vitamin mixture) does not act directly on D. magna but via the algae by changing their nutritional value for Daphina.5. Addition of vitamins to the medium in which the algal food is grown with crustacea may allow continuous cultures of herbivorous crustacea which are considered difficult to grow.
TL;DR: The bay mussel Mytilus edulis (Linnaeus) and the California sea mussel mytilus californianus (Conrad) have a common diploid chromosome number 28 (n = 14) that is, there were 14 bivalents during meiosis and 28 chromosomes during mitosis as discussed by the authors.
Abstract: The bay mussel Mytilus edulis (Linnaeus) and the California sea mussel Mytilus californianus (Conrad) have a common diploid chromosome number 28 (n = 14) that is, there were 14 bivalents during meiosis and 28 chromosomes during mitosis. A total of 35 specimens of the two species were examined from several intertidal locations in Puget Sound and the Northwest Pacific coast of the United States. The number of meiotic bivalents in stripped or spawned eggs was always constant but aneuploid counts of mitotic chromosomes were made in cleaving eggs and embryos. Heteromorphic bivalents in meiotic plates and heteromorphic homologues in mitotic karyotypes were observed. The number of metacentric, submetacentric and acrocentric chromosomes was variable. There were 2 to 6 pairs of acrocentrics in different complements. This polymorphism indicates the existence of pericentric inversions or centric-shifts in both meiotic and mitotic chromosomes.
TL;DR: The results showed large doses of ecdysterone caused complete metamorphosis of the transplanted imaginal disc, including eversion of the disc, formation of a pupal cuticle, and formation of adult cuticle with bristles, hairs and sensilla arranged in normal orientation.
Abstract: The effects of molting hormone on the development of imaginal discs of Drosophila melanogaster were investigated. Imaginal leg discs from mature larvae were transplanted into the abdomens of fertilized adult female flies. The hosts were injected with a solution of a phytoecdysone—ecdysterone or cyasterone. The results showed: (1) Large doses of ecdysterone (over 1200 µg/g= 1.2 µg/fly) caused complete metamorphosis of the transplanted imaginal disc, including eversion of the disc, formation of a pupal cuticle, and formation of adult cuticle with bristles, hairs and sensilla arranged in normal orientation. (2) Ecdysterone was necessary as a sustained stimulus, and did not act merely as a trigger to metamorphosis. (3) Cyasterone was a more potent molting hormone than ecdysterone. The technique promises to simplify investigation of pattern formation and other developmental problems in Drosophila.
TL;DR: It is believed that radioactive material was transported from the pen-visceral coelom via the perihemal canals and fixed as an insoluble mucopolysaccharide by the cells of the hemal septum, and distributed through all regions of the body wall ...
Abstract: 1. Specimens of the starfish, Echinaster echinophorus, were injected in the disc region with small quantities of C14-labeled amino acid mixture. After periods ranging from 1 hour to 75 days they were sacrificed and histological sections of their arms prepared as stripping film autoradiographs.2. By 1 hour after the injection bound radioactive material was detected in most tissues in the proximity of the coelomic cavity, and while translocations from these areas were noted, most of the labeled material remained in these areas even after 75 days.3. By 24 hours large quantities of radioactivity were found spasmodically in the hemal septum and traced dispersing outward into the connective tissue layer of the tube feet and the suckers. It is believed that this material was transported from the pen-visceral coelom via the perihemal canals and fixed as an insoluble mucopolysaccharide by the cells of the hemal septum.4. By 5 days significant dispersion of radioactive material through all regions of the body wall ...
TL;DR: It is clearly demonstrated that Thompson (1903) attributed his larvae to the wrong species and a suggestion is made as to the correct identity of his larvae.
Abstract: Thompson (1903) described from the plankton four zoeae and a megalopa which he ascribed to Pagurus longicarpus. Although his verbal description of the external anatomy is incomplete, his figures are adequate to identify accurately the species with which he was working. His description of the internal anatomy is the most complete study available for any decapod larva. He indicated that some larvae of P. annulipes were included in his study material but that he was unable to differentiate the two species. MacDonald, Pike, and Williamson (1957) and Pike and Williamson (1959, 1960) described the larvae of several British and Mediterannean Pagurus species from carefully constructed plankton series. They were able to distinguish three types of larvae in this genus, based on 12 larval characteristics (several of which were composites of two characteristics), suggesting that the genus Pagurus may be polyphyletic, but no division of the genus was attempted for lack of adult characteristics supporting the larval data. Larvae of several additional Pagurus species have been described from culture experiments by Coffin (1958, 1960), Hart (1937), Provenzano and Rice (1964) and Shenoy (1967). In addition, P. bernhardus has been cultured by Bookhout (1964) and A. Le Roux (personal communication) and shown to agree in all essentials with the description given by MacDonald et al. (1957). This paper deals with the external anatomy of P. longicarpus larvae reared in the laboratory. It is clearly demonstrated that Thompson (1903) attributed his larvae to the wrong species and a suggestion is made as to the correct identity of his larvae.
TL;DR: The most important implication of these findings is that the population structure and amount of genetic variability in ectoprocts (and by implication in other marine organisms) is fundamen...
Abstract: Proteins of marine species of the Phylum Ectoprocta can be easily separated by zone electrophoresis on polyacrylamide gels. Many bands revealed by electrophoresis represent the product of individual genetic loci from which gene and genotype frequencies were calculated. Results are reported for 19 loci which are responsible for the formation of esterases, malate dehydrogenase and "leucine" aminopeptidase in Schizoporella unicornis and Bugula stolonifera.Observed genotype frequencies correspond closely with those predicted by Hardy-Weinberg equilibria indicating that these marine ectoprocts are dominantly outbreeding and that panmictic local populations cover an area of square meters. In addition, 25.0-54.5% of the diagnosed loci are polymorphic, depending on the species. Forty-two % of all loci identified are polymorphic.The most important implication of these findings is that the population structure and amount of genetic variability in ectoprocts (and by implication in other marine organisms) is fundamen...
TL;DR: The histological characteristics of the cement gland cells of barnacles have been compared in B. nubilis, B. psittacus, B., eburneus and B. balanoides to find out how the secretion of cement is brought about by muscle fibers that pass through the connective tissue.
Abstract: 1. The histological characteristics of the cement gland cells of barnacles have been compared in B. nubilis, B. psittacus, B. eburneus, B. balanoides and B. amphitrite. 2. In B. balanoides, the cement gland cells show a very simple composition; they are situated at the base of the animal and the secretion appears scattered throughout the cytoplasm. The cement apparatus of B. amphitrite and B. eburneus looks like that of B. tintinnabulum, but in B. psittacus and B. nubilis the cement gland cells appear more complex. 3. The extrusion of the cement secretion is brought about by muscle fibers that pass through the connective tissue, and in B. psittacus and B. nubilis by elastic fibers around the secondary and principal canal systems.
TL;DR: Gymnotids of 13 species were trawled in water 10-20 m deep; all emitted weak electrical discharges; each fish had a typical frequency of discharge; each species had a Typical range of frequency but there were overlaps between species.
Abstract: Gymnotids of 13 species were trawled in water 10-20 m deep; all emitted weak electrical discharges. Each fish had a typical frequency of discharge; each species had a typical range of frequency but there were overlaps between species. Waveforms of discharge were similar in several species. Electric organs were derived from muscle tissue in most low frequency species and from nerve tissue in high frequency species. Diurnal movements of fishes were followed electronically. Fishes formed aggregations in 15-20 m deep water about 100 meters from shore during the day and dispersed along the shore at night. Individual daytime aggregations were re-established each morning.
TL;DR: The present study indicates that exposure of an anteroventral respiratory membrane, assumption of a head-down position, improvement of gulping technique, control and slowing of ventilation, and greater efficiency of exchange between branchial gas and blood also contribute critically to the maturing fish's increasing independence of aquatic life.
Abstract: The amphibious clingfish Sicyases sanguineus attaches by means of its ventral sucker to vertical surfaces of large exposed rocks splashed by the cool and heavy surf of Chile and southern Peru. Although adult and halfgrown fish tolerate diluted seawater and can survive at least a few hours in warm and stagnant water, they seldom, if ever, occur in isolated tidal pools, bays, or estuaries.Factor analysis indicates that clingfish come out of the water more abundantly during periods of calm and often turn head-down. They avoid drying rocks outside the spray zone and emerge onto higher rocks as the water level rises. Adult fish come out of the water more abundantly in remote areas relatively undisturbed by civilization. Insolation apparently does not directly alter the abundance of clingfish, which act so as to minimize evaporative water loss and overheating.Terrestrial fish breathe air held in their gill cavities, probably through their gills. As they come out of the water, fish gulp air, then stop all opercu...
TL;DR: Although oilbirds and swiftlets can certainly avoid large obstacles by echoloca tion, there is very little evidence concerning their proficiency, and the authors know almost nothing about the minimum size of object that can be detected.
Abstract: The specializations of bats of the suborder Microchiroptera for echolocation have naturally suggested that nocturnal or cave dwelling birds might orient themselves in the same way. Numerous preliminary tests of several species (mostly unpub lished) have yielded negative results, and only two avian genera have been clearly demonstrated to use echolocation. These are the oilbirds of South America. Steatornis caripensis (Griffin, 1954) , and certain species of the genus Collocalia. the cave swiftiets of Southeast Asia (Griffin, 1958 ; Novick, 1959 ; Medway, 1959. 1967) . The orientation sounds of both species are brief audible clicks lasting a few milliseconds. They tend to have a peak of energy between two and eight kHz, but also a very broad acoustic spectrum extending to ultrasonic frequencies. The clicks are emitted primarily in dim light or darkness and increase in repetition rate like those of bats and cetaceans when difficult orientation problems arise. A ver similar sort of echolocation is practiced by bats of the genus Rousettus, the only known case in the suborder Megachiroptera. Although oilbirds and swiftlets can certainly avoid large obstacles by echoloca tion, there is very little evidence concerning their proficiency, and we know almost nothing about the minimum size of object that can be detected. In contrast consid erable data on this point are available from bats of the suborder Microchiroptera (Griffin, 1958; Suthers, 1965, 1967; Schnitzler, 1966). Griffin, Novick, and Korn field (1958) measured the size of cylindrical obstacles that could be detected b a single individual Rousettus aegypticus. With sufficient practice this animal could detect wires as small as 0.46 millimeter diameter at distinctly above the chance level. Rousettus uses as orientation sounds audible clicks that are similar to those of Collocalia and Steatornis, but in view of evidence that most small mammals can hear well at ultrasonic frequencies (RaIls, 1965) it is difficult to ascertain which part of the broad frequency spectrum emitted by Rousettus generates the echoes by which it detects small obstacles. Medway (1967) studied the ability of Collocalia fuciphaga to avoid vertical wooden rods one centimeter square spaced 15 cm apart. These birds with a wingspan of about 27 cm showed no ability to avoid these obstacles when first encountered in darkness. But they maneuvered between them almost perfectly in the light. Their performance in the dark improved on successive flights, but the experiment did not demonstrate how much of this improvement resulted from learning the positions of the obstacles and how much from echoloca lion. The many species of Collocalia appear to differ widely in their use of dark caves and their reliance on echolocation. During the 1969 ALPHA HELIX expedition to New Guinea we studied the orientation sounds of Collocalia vanikorensis granti, and carried out preliminary experiments that indicate the approximate threshold size of cylindrical obstacles
TL;DR: The seasonal evolution of the gonads of A. chiajei during the period from April 1965 until March 1966 has been described and the problem of maturation of the primary oocytes is discussed.
Abstract: 1. The seasonal evolution of the gonads of A. chiajei during the period from April 1965 until March 1966 has been described. The reproductive cycle allows a period of sexual rest at the end of autumn, a period of growth in winter, a period of maturity in spring and in summer, and an egg-shedding period from the end of summer until the middle of autumn.2. The seasonal cycle of planktonic larva was studied during a period of three years. The larvae appear in autumn; however, a few of them were caught in spring and in summer.3. The problem of maturation of the primary oocytes is discussed. The larvae described by Muller (1853), Mortensen (1920) and Chadwick (1914) are related to A. chiajei. The periods of reproduction of this species in various Northern and Mediterranean regions are specified.
TL;DR: Calcification during regeneration of experimentally fractured spines of the sea urchin, Strongylocentrotus purpuratus (Stimpson), was studied quantitatively under different conditions with calcium-45 as a tracer to infer that carbonic anhydrase is involved in calcification of regenerating spines.
Abstract: 1. Calcification during regeneration of experimentally fractured spines of the sea urchin, Strongylocentrotus purpuratus (Stimpson), was studied quantitatively under different conditions with calcium-45 as a tracer. 2. Fractured spines rapidly incorporated 45Ca in vivo or in vitro after a lag period of about two days. The lag period is attributed to wound healing and reorganization of tissue at the site of fracture. 3. Additional experiments were conducted while calcification was in progress by allowing fractured spines to regenerate for four days in vivo followed by incubation in 45Ca in vivo or in vitro up to 24 hours. In these experiments incorporation of the label was nearly linear with time and no significant difference was observed in the rate of uptake of 45Ca between regenerating spines incubated in vivo and those from the same urchin incubated simultaneously in vitro. 4. Incorporation of 45Ca in vitro was directly proportional to temperature between 4.7° and 20° C, at which a maximum occurred. A temperature of 26° C appeared to be lethal and little incorporation of 45Ca took place. Values of Q10 and the energy of activation varied inversely with temperature, with overall means of 2.72 and 15,504 calories per mole, respectively, between 4.7° and 20° C. 5. Diamox (acetazolamide) at concentrations from 10-3 to 10-6 M, inhibited incorporation of 45Ca in vitro by 50% to 61%. It is inferred from these results that carbonic anhydrase is involved in calcification of regenerating spines of S. purpuratus.
TL;DR: Experiments to test food preference showed that specimens of Paranemertes from all study areas strongly preferred nereids to members of other polychaete families.
Abstract: 1. Paranemertes peregrina, an abundant hoplonemertean in rocky and muddy intertidal habitats of Washington, feeds on polychaetes during low tide periods.2. Feeding by Paranemertes involves three steps. The first stage is a recoil of the Paranemertes' head upon contact with a prey. Contact must be made with the prey; Paranemertes does not find prey by distance chemoreception. The proboscis is everted and wraps around the prey in step two. The prey is temporarily paralyzed or is killed. In step three the prey is ingested by means of sucking motions from muscles around the mouth. Defecation occurs from 12 to 33 hours after feeding.3. Specimens of Paranemertes ate mainly nereid polychaetes at the three study areas where nereids were available. At the fourth study area the nemerteans ate a wider variety of polychaetes. Experiments to test food preference showed that specimens of Paranemertes from all study areas strongly preferred nereids to members of other polychaete families.4. Nereid polychaetes have a swi...
TL;DR: Experiments showed that at two distinct levels of temperature acclimation, superabundant oxygen in the water could produce a definite improvement either in time of survival at a fixed lethal temperature or in lethal temperature reached as a result of heating.
Abstract: A hypothesis may be made out that the respiratory/circulatory, and possibly the oxygen transport, systems are importantly involved in thermal death of goldfish. Experiments showed that at two distinct levels of temperature acclimation, superabundant oxygen in the water could produce a definite improvement either in time of survival at a fixed lethal temperature or in lethal temperature reached as a result of heating.Despite this positive effect of high oxygen a clear cut failure of oxygen, in excess of about 5 atmospheres (partial pressure), to produce further improvement in thermal tolerance suggests the failure of some critical system directly affected by temperature.The experiments, while revealing nothing of the detailed mechanisms involved, certainly do not invalidate the hypothesis proposed, and open a way to further investigation.
TL;DR: Differences between the different species in the action of ecdysone are of a quantitative rather than qualitative nature.
Abstract: 1. The effect of ligation on pupariation in the front or hind parts of larvae of four species of flies, Calliphora erythrocephala, Phormia regina, Sarcophaga bullata, and S. argyrostoma was investigated. Ligation causes effects of delay or inhibition of pupariation which are very differently expressed in the four species. A large proportion of pre- or postcritically ligated specimens of P. regina and S. bullata altogether fail to pupariate in the anterior part. This makes these species unsuitable test subjects for the pupariation test for ecdysone.2. Test abdomens of C. erythrocephala required significantly less ecdysone for a given pupariation effect when also injected with a CNS-extract. Tanning was also considerably accelerated in this case.3. The value of the pupariation unit of ecdysone is influenced by a number of factors, such as age at the time of ligation, the waiting period between ligation and injection, the dilution effect of the solvent, and the simultaneous action of a neurohormone. The requ...
TL;DR: The hypothesis was derived that the swarms of mature medusae in nature are the direct result of a "bloom" in zooplankton which occurred 5-7 weeks previously and stimulated first hydroid development and in consequence the formation of gonangia.
Abstract: 1. A method was described by which hydroid colonies, each on a microscopic slide, were raised from individual planulae of the leptomedusa known as Phialidium gregarium. 2. Growth and behavior of approximately 30 cultures were observed and quantitated through nearly 2 months. Cultures produced gonangia and medusae 3-7 weeks after fertilization of the egg. 3. Gonosome development was always preceded by a burst of hydroid development 5-9 days previously. This burst appeared to be initiated entirely by an abundant food supply (brine shrimp). 4. Medusae were liberated 4-5 days after gonangia first appeared. From the growth rate of medusae under the less than optimal laboratory conditions, it was estimated that sexual maturity may be reached in approximately 3 weeks. The lifespan of the medusae probably does not exceed 3 months. 5. A small number of cultures wintered in an open cage in the sea. At the end of November they were found in a greatly reduced state and possessed only a very few, very small hydranths. At the end of March they were in the early phases of vigorous trophosomal growth and the gonosome had just begun to flourish. 6. From the behavior of clonal colonies in the laboratory, the hypothesis was derived that the swarms of mature medusae in nature are the direct result of a "bloom" in zooplankton which occurred 5-7 weeks previously and stimulated first hydroid development and in consequence the formation of gonangia. 7. Morphological characteristics of the hydroid colonies were described and their variability under laboratory conditions recorded and discussed. It was shown that many taxonomic features such as size, branching, number of tentacles and annulations depend quantitatively on the age of the individual colony, its state of nutrition and on genetic factors. 8. The hydroid belongs to the genus Clytia (Lamouroux, 1816). A careful comparison was made with species of the genus as described for the Puget Sound region and California. It was concluded that none of these delineates unambiguously the morphological features of this hydroid. A tentative name for the hydroid was assigned according to priority principles as Clytia gregaria. It was suggested that Phialidium gregarium may be the most appropriate name for the species in both its phases.