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Full-Text Articles in Life Sciences
Seawater Flow Into The Digestive System Of Actinotroch Larvae (Phoronida), William Jaeckle
Seawater Flow Into The Digestive System Of Actinotroch Larvae (Phoronida), William Jaeckle
William Jaeckle
Actinotroch larva (Phoronida) concentrate and collect food particles during their planktonic existance. Reported mechanisms of particle capture include both ciliary reversal and direct interception along the larval tentacles, and suction of particle-containing seawater into the larval vestibule. These diverse mechanisms explain collection of particles, but not subsequent ingestion. Particle delivery into the digestive system is accomplished, at least in part, by the activity of the esophageal cilia. If and how the beat frequency of esophageal cilia is modified by the presence or absence of particulate or dissolved organic materials remains unknown for actinotroch larvae.
Distribution Of Bipinnaria And Pilidium In Relation To Physical Structure And Uv-B Light In The Water Column Off Anvers Island, Antarctica, I. Bosch, William Jaeckle, Deneb Karentz
Distribution Of Bipinnaria And Pilidium In Relation To Physical Structure And Uv-B Light In The Water Column Off Anvers Island, Antarctica, I. Bosch, William Jaeckle, Deneb Karentz
William Jaeckle
Feeding larvae of Antarctic bottom invertebrates have proven to be scarce in the plankton and consequently our knowledge of their ecology is limited. We collected bipinnaria larvae assignable to the genus Odontaster and several types of pilidium larvae of nemertean worms in quantitative net tows taken during the austral spring and summer 1997-1998 and considered their distribution with respect to the density stratification of the water column and the potential exposure to UV-B (λ = 308 nm). The average number of pilidium and bipinnaria larvae in the upper 40 m of the water column was 0.5 ± 1.0 per m3 …
Size And Organic Content Of Eggs Of Marine Annelids, And The Underestimation Of Egg Energy Content By Dichromate Oxidation, William Jaeckle, Bruno Pernet
Size And Organic Content Of Eggs Of Marine Annelids, And The Underestimation Of Egg Energy Content By Dichromate Oxidation, William Jaeckle, Bruno Pernet
William Jaeckle
Dichromate oxidation is a simple technique that is often used to estimate the energy content of eggs in studies of marine invertebrate life histories (1). We used this method to measure the energy contents of the eggs of 12 species of marine annelids. In combination with measures of egg ash-free dry weight (AFDW), these data yielded estimates of AFDW-specific energy density that were mostly lower than the average weight-specific energy density of carbohydrates. This seemed unlikely to be correct, as invertebrate eggs typically contain little carbohydrate and instead are composed primarily of energy-dense protein and lipid (1, 2). After validating …
Identification Of Asteroid Genera With Species Capable Of Larval Cloning, K. E. Knott, E. J. Balser, William Jaeckle
Identification Of Asteroid Genera With Species Capable Of Larval Cloning, K. E. Knott, E. J. Balser, William Jaeckle
William Jaeckle
Asexual reproduction in larvae, larval cloning, is a recently recognized component of the complex life histories of asteroids. We compare DNA sequences of mitochondrial tRNA genes (Ala, Leu, Asn, Pro and Gln) from larvae in the process of cloning collected in the field with sequences from adults of known species in order to identify asteroid taxa capable of cloning. Neighbor-joining analysis identified four distinct groups of larvae, each having no, or very little, sequence divergence (p distances ranging from 0.00000 to 0.02589); thus, we conclude that each larval group most likely represents a single species. These field-collected larvae cannot be …
A Long Way From Home: Transatlantic Sea Star Migration, William Jaeckle, Paul Kehle
A Long Way From Home: Transatlantic Sea Star Migration, William Jaeckle, Paul Kehle
William Jaeckle
For a marine biologist strolling along the eastern coast of South America, finding some sea stars (popularly called starfish, and technically members of the class Asteroidea of the phylum Echinodermata) is not all that unusual. However, when closer inspection reveals the sea stars to be ones that are also found on the shores of the western coast of Africa, the marine biologist now faces an interesting question: How did these sea stars come to be so far from home? Originally published in Consortiumand used with permission.
The Potential For Ontogenetic Vertical Migration By Larvae Of Bathyal Echinoderms, William Jaeckle, Craig M. Young, Michael G. Devin, Suki U.K. Ekaratne, Sophie B. George
The Potential For Ontogenetic Vertical Migration By Larvae Of Bathyal Echinoderms, William Jaeckle, Craig M. Young, Michael G. Devin, Suki U.K. Ekaratne, Sophie B. George
William Jaeckle
Planktotrophy is a relatively common developmental mode among bathyal and abyssal echinoderms, but the sources of food used by deep-sea planktotrophic larvae remain generally unknown. Very few deep-sea echinoderm larvae have been collected in plankton samples, so we do not know whether larvae migrate to the euphotic zone to feed or if they rely on bacteria or detritus at greater depths. We approached this question indirectly by investigating whether larvae of bathyal echinoids can tolerate the temperatures they would encounter in the euphotic zone and whether they possess sufficient energy stores to migrate to the euphotic zone without feeding. Twenty-four …
Ultrastructure Of The Coeloms Of Auricularia Larval (Holothuroidea Echinodermata): Evidence For The Presence Of An Axocoel, E. J. Balser, E. E. Ruppert, William Jaeckle
Ultrastructure Of The Coeloms Of Auricularia Larval (Holothuroidea Echinodermata): Evidence For The Presence Of An Axocoel, E. J. Balser, E. E. Ruppert, William Jaeckle
William Jaeckle
A hallmark feature of echinoderm larvae is the development of the left anterior coelom. This coelom, called the axohydrocoel, consists of the morphologically distinct, but undivided, left axocel and hydrocel. The axocoelic portion forms a duct that opens to the exterior via a pore on the dorsal surface of the animal. Holothuroid larvae are thought to lack an axocoel, but develop an anterior coelom, duct, and pore that are regarded as parts of the hydrocoel. New ultrastructural data, however, show that holothuroid auricularia larvae possess an axocel and hydrocel united together into an axohydrocoel. During development the anterior coelom consists …
Amino Acid Uptake And Metabolism By Larvae Of The Marine Worm Urechis Caupo (Echiura), A New Species In Axenic Culture, William Jaeckle, Donal T. Manahan
Amino Acid Uptake And Metabolism By Larvae Of The Marine Worm Urechis Caupo (Echiura), A New Species In Axenic Culture, William Jaeckle, Donal T. Manahan
William Jaeckle
Axenic (bacteria-free) larval cultures of the marine echiuran worm, Urechis caupo, were reliably obtained by aseptically removing gametes directly from the gamete storage organs. Trochophore larvae only removed neutral amino acids from seawater as measured by high-performance liquid chromatography (HPLC). There was no detectable uptake, as measured by HPLC, of acidic or basic amino acids. Kinetic analysis showed that the transport system for alanine in 4-day-old larvae had a Kt of 4-6 μM and a Jmax of 9-10 pmol larva-1 h-1. Following a 50-min exposure, the majority of the radio-activity (95%) from 14C-alanine was found in the trichlo-roacetic acid-soluble fraction. …
Feeding By A “Nonfeeding” Larva: Uptake Of Dissolved Amino Acids From Seawater By Licithotrophic Larvae Of The Gastropod Haliotis Refescens, William Jaeckle
Feeding By A “Nonfeeding” Larva: Uptake Of Dissolved Amino Acids From Seawater By Licithotrophic Larvae Of The Gastropod Haliotis Refescens, William Jaeckle
William Jaeckle
No abstract provided.
Growth And Energy Imbalance During The Development Of A Lecithotrophic Molluscan Larva (Haliotis Rufescens), William Jaeckle, Donal T. Manahan
Growth And Energy Imbalance During The Development Of A Lecithotrophic Molluscan Larva (Haliotis Rufescens), William Jaeckle, Donal T. Manahan
William Jaeckle
Larvae of the gastropod Haliotis rufescens are classified as "nonfeeding" because they cannot capture particular foods. However, for only 1 out of 5 independent cultures was a net decrease observed in dry organic weight during the complete period of larval development (5 to 7 days). In fact, there were net increases in dry organic weight from the oocyte (day 0) to the newly formed veliger larvae (2-day-old). These weight increases during early development could be explained by increases in the amounts of specific biochemical components of the larvae, relative to oocytes. The metabolic rates of larvae were measured (oxygen consumption) …