Physiology Commons^™

Seawater Flow Into The Digestive System Of Actinotroch Larvae (Phoronida), William Jaeckle

Scholarship

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, William Jaeckle

Scholarship

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 …

Coelomogenesis And Nutrition Of Clonally Produced Asteroid Larvae, William Jaeckle

Scholarship

Asexual reproduction by planktotrophic larvae of asteroids is an unusual life history strategy exhibited by several species in the families Luididae, Oreasteridae, Ophidiasteridae, and Asteriidae. Larvae of the former three families reproduce asexually in the field, while the asteriid Pisaster ochraceus has produced clones when larvae are reared in the laboratory. Our knowledge of the processes involved in larval cloning and the biology of the developing clone is fragmentary in nature. We used light, electron, and scanning laser confocal microscopy to study clones that develop through paratomy of the posterolateral larval arms. The archenteron forms by a modified form of …

Size And Organic Content Of Eggs Of Marine Annelids, And The Underestimation Of Egg Energy Content By Dichromate Oxidation, William Jaeckle, Bruno Pernet

Scholarship

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 …

Variability In Broods Of The Seastar Leptasterias Aequalis, William B. Jaeckle, Brian L. Bingham, Kehualani Giles

Scholarship

Enormous variation exists in the reproductive output of marine invertebrates (e.g., in the numbers of em¬bryos produced, the volumes of embryos, and the energy that they contain). It is not clear why there is such great variability or what the population-level consequences are. We sampled a population of the brooding seastar Leptasterias aequalis (Stimpson, 1862) to collect basic information on brood sizes, embryo volume, and embryo energy content with a goal to better understand the reproductive ecology of this species. We collected brooding females in February and again in April. We measured the size of their broods and sampled the …

Identification Of Asteroid Genera With Species Capable Of Larval Cloning, K. E. Knott, E. J. Balser, William Jaeckle

Scholarship

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 …

A Long Way From Home: Transatlantic Sea Star Migration, William Jaeckle, Paul Kehle

Scholarship

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.

Variation In Alanine Transport Among Sibling Lecithotrophic Larvae Of Holothuroid And Asteroid Echinoderms, William Jaeckle

Scholarship

Variation in development rate (e.g., time to metamorphic competence) among sibling larvae has been reported, but inter-individual differences in physiological processes has received comparatively little attention.

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

Scholarship

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 …

Transport And Metabolism Of Alanine And Palmitic Acid By Field-Collected Larvae Of Tedania Ignis (Porifera, Demospongiae): Estimated Consequences Of Limited Label Translocation, William B. Jaeckle

Scholarship

The epidermis of larvae of Tedania ignis(Porifera, Demospongiae) is uniformly ciliated except for the posterior pole. The epidermal cells are long, columnar, and monociliate; each cilium arises from an epidermal crypt; symbiotic bacteria were not observed in larval cells. These lecithotrophic ("nonfeeding") larvae can feed by assimilating dissolved organic materials (DOM) from seawater. Larvae transported both the amino acid alanine (mean = 2.73 pmol larva^-1 h^-1; [S] = 1 µM) and the fatty acid palmitic acid (mean = 16.27 pmol larva^-1 h^-1; [S] = 1 µM) from seawater. Following assimilation, the …

Multiple Modes Of Asexual Reproduction By Tropical And Subtropical Sea Star Larvae: An Unusual Adaptation For Genet Dispersal And Survival, William Jaeckle

Scholarship

Sea star larvae (Echinodermata: Asteroidea), collected from the subtropical Northwest Atlantic Ocean, exhibited three distinct modes of asexual reproduction. A number of different bipinnariae and brachiolariae reproduced by paratomous cloning of the posterolateral arms. This morphogenesis was identical to that of larvae assignable to the genus Luidia. A second mode of asexual reproduction involves the autotomization of an anterior portion of the preoral lobe. Primary larvae with preoral lobes of varying sizes and free-swimming preoral lobes of various stages of morphological development were simultaneously collected. The free-swimming preoral lobes developed complete digestive systems and ultimately assumed the form of …

Rates Of Energy Consumption And Acquisition By Lecithotrophic Larvae Of Bugula Neritina (Bryozoa: Cheilostomata), William Jaeckle

Scholarship

Lecithotrophic larvae of the cheilostome bryozoan, Bugula neritina (L.), lose metamorphic competence 12 to 24 h after release from the maternal zooid. The high respiration rate of newly released larvae (mean=306.3 pmol O₂ larva^-1 h^-1, range= 149.3 to 466.6, n=18 trials, 22.5 °C) from adults collected at Link Port, Fort Pierce, Florida during the winter/spring of 1990-1991 reflects their active swimming behavior. The average energy con¬tent per larva was 15.24 mJ (range: 13.35 to 20.17 mJ ind^-1, n=5 groups). If all cells have an identical energy content and metabolic rate, then 2 and 20% …

Ultrastructure Of The Coeloms Of Auricularia Larval (Holothuroidea Echinodermata): Evidence For The Presence Of An Axocoel, E. J. Balser, E. E. Ruppert, William Jaeckle

Scholarship

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 …

Experimental Manipulations Of The Organic Chemistry Of Seawater: Implications For Studies Of Energy Budgets In Marine Invertebrate Larvae, William Jaeckle

Scholarship

Correct measurement of changes in biomass and metabolic rates over time are two essential elements for the accurate construction of energy budgets for invertebrate larvae. Both components of larval energetics are altered by changes in the organic chemistry of the seawater. Axenic (bacteria-free) veliger larvae (88 µm shell length) of the bivalve Crassostrea gigas (Thunberg, 1795) had a 53% enhancement of their metabolic rate relative to control values (5.8 ± 0.6 pmol larva -1 h -1 , x¯ ± 1 SE) when exposed to seawater to which 1 µM glucose had been added. Gastrulae increased their rate of respiration by …

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

Scholarship

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 K_t of 4-6 _μM and a J_max of 9-10 pmol larva^-1 h^-1. Following a 50-min exposure, the majority of the radio-activity (95%) from ^{14 …}

Ontogenic Changes In The Rates Of Amino Acid Transport From Seawater By Marine Invertebrate Larvae (Echinodermata, Echiura, Mollusca), Donal T. Manahan, William Jaeckle, Saeid D. Nourizadeh

Scholarship

Transport rates of amino acids were determined for larvae of different ages of the echiuran worm Urechis caupo, the gastropod Haliotis rufescens, the bivalve Crassostrea gigas, and the sea urchin Strongylocentrotus purpuratus. All larval forms showed an increase in the transport rate of amino acids during development. Trochophores of U. caupo increased their rate of net flux for each of 5 amino acids (100 nM each) by a factor of 1.6 and 2.2 during 1-3 days and 4-8 days, respectively, for two independent cultures. In H. rufescens, the maximum transport capacity (J_max) …

Growth And Energy Imbalance During The Development Of A Lecithotrophic Molluscan Larva (Haliotis Rufescens), William Jaeckle, Donal T. Manahan

Scholarship

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) …

Feeding By A “Nonfeeding” Larva: Uptake Of Dissolved Amino Acids From Seawater By Licithotrophic Larvae Of The Gastropod Haliotis Refescens, William Jaeckle

Scholarship

No abstract provided.