Sessile Stages Research Articles

Back to the roots, Part 1—early life cycle data of Rhopaliophora (Scyphozoa, Cubozoa and Staurozoa)

The phylogeny of the Rhopaliophora (Scyphozoa, Cubozoa and Staurozoa) has been discussed and modified extensively up to the present day. Attempting to finally solve this question, the morphology and development of the different early life history stages stages of 17 scyphozoan, 2 staurozoan and 8 cubozoan species were investigated. Due to the magnitude of the study, the findings will be published in two parts. This first part will focus on the comparison of early life cycle stages, the second part (to be published in the following issue of Plankton & Benthos Research) will focus on the evolutionary connection and systematics. The present part of the study focused on the morphology of different types of sessile stages (polyps), the processes of strobilation and metamorphosis, and the resulting products (residues and ephyrae/young medusa) and their further development. The different morphological characters in the polyps helped to categorize them into types. By using the strobilation rates and information on the way morphological characters changed during the process of strobilation/metamorphosis, the strobilae were able to be separately categorized.

Polyp dropout in a solitary cold-water coral

Scleractinian corals feature both sessile and mobile stages and diverse modes of development. In some cases, development can be reversed. Examples include polyp detachment in response to environmental stress (bail-out or polyp expulsion) and reverse metamorphosis, where juveniles detach from the primary skeleton and revert to the mobile stage. Here, we provide aquaria and field evidence of a new form of reverse development: polyp dropout in the solitary cold-water coral Caryophyllia huinayensis. It features tissue retraction and detachment of an entire adult polyp from the skeleton in the putative absence of a stressor. The dropout polyp remains viable and continues to live for many weeks, albeit in a rather collapsed state lacking a well-developed hydroskeleton. We carried out a long-term (37 months) rearing experiment under constant aquaria conditions and found polyp dropout in four out of 83 individuals. Detachment was accompanied by the extrusion of mesenterial filaments through perforations in the body wall. We believe this resulted in the loss of the hydroskeleton, which prevented the dropouts to subsequently resettle or form a new skeleton. As opposed to other known forms of reverse development, the new form is not accompanied by reversible metamorphosis, abandonment of the colonial way of life, nor is it a survival or asexual reproduction strategy. We found field indications of polyp dropout in Patagonian field populations of C. huinayensis, where 1.4 ± 0.8% (mean ± SD, N = 9322) of the polyps of the natural population showed partial detachment indicative of imminent dropout in the putative absence of external impact. Polyp dropout is the first record of polyp detachment in a solitary CWC with possible repercussions for adult coral mobility, evolution and Stanley’s (2003) ‘naked coral’ hypothesis.

Spawning habitat suitability for coastal cutthroat trout: Microhabitat and mesohabitat

Abstract The conservation of aquatic species with complex life histories requires the protection of habitat for each life stage. Coastal cutthroat trout (Oncorhynchus clarkii clarkii) exhibit both mobile and sessile stages and are of conservation concern in north‐western North America. Models that predict how habitat changes with flow can inform water management for the species but rely on habitat descriptors that change with flow and are not suited to sessile life stages. Spawning and incubation habitat availability and use for coastal cutthroat trout were assessed in mesohabitats and microhabitats. Primary channel units were tallied, dimensions were measured, redds were counted, and redd locations within channel units were measured. Primary channel units were subdivided based on relative residual depth (RRD, bed elevation in relation to maximum pool depth) and hydraulic control (HC, the lowest point on the highest ridge across the riffle that controls the water surface elevation in the upstream pool). Habitat suitability was calculated for depth (D), velocity (V), Froude number (Fr), substrate (S), RRD, and channel units. Redds in riffles and pools were close to hydraulic controls; suitability decreased upstream in pools and downstream in riffles. Maximum suitability values were: 21–24 cm for D, 0.05–0.10 for RRD, 61–64 cm s−1 for V, >0.80 for Fr, and 1.3 to <3.8 cm for S. Channel units, RRDs, and microhabitat better identified spawning habitat than microhabitat alone. The results suggest that RRD and stage of zero flow are good indicators of habitat suitability for spawning through fry emergence and could be adapted for use with other species. This work generates criteria for delineating flow‐independent channel units that can be used to set more protective instream flows, prioritize the acquisition of instream water or conservation easements to protect critical habitat, and inform restoration projects to optimize habitat availability.

Detection and classification of Lepeophterius salmonis (Krøyer, 1837) using underwater hyperspectral imaging

Salmon louse, or sea lice, (Lepoptherius salmonis) represents practical, economical and fish welfare challenges for salmon farming (Hamre et al., 2013) and for the free-living stocks of salmon. There is an urgent need in the industry for a system that provides reliable numbers of louse on farmed salmon. Underwater hyperspectral imaging represents a potential new technique for louse counting in sea cages. In laboratory studies, the UHI technology could detect and classify pre-adults (pre-adult I and II), adult males and adult females (ovigerous) of sea lice based on the difference in their spectral characteristics. A model was built for detection of lice on the salmon and the UHI had a detection success ranging from 67 to 100 % with an average of 82%. A classification of the detected lice was performed for pre-adults, adult males and ovigerous lice and had a prediction accuracy of 85% when lice were divided into three groups (pre-adults, adult male and ovigerous lice) and 93% when lice were divided in two groups, ovigerous lice and all the other mobile lice (pre-adults and adult male). An automatic procedure for in situ measurements of louse infected salmon could deliver a data basis several times higher than the traditional counting system. The next generation of UHI louse detector should be developed with a higher spatial resolution to be able to detect also the sessile stages of lice. For succeeding with in situ classification of L. salmonis, correction algorithms to compensate for the impact of water between the UHI and lice need also to be developed.

English

Mango (Mangifera indica L.) is the third most important fruit crop in the tropics following citrus and banana. It is consumed as a fresh fruit and different forms of preparations for its multifaceted nutritional values. Mango production in Ethiopia is constrained by infestation of white mango scale (WMS), Aulacaspis tubercularis Newstead. White mango scale was recorded from Ethiopia for the first time in 2010, in a mango orchard in Loko in the western part of the country. This study was conducted from June 2013 to May 2014 to document the population dynamics of white mango scale in Western Ethiopia. Randomized Complete Block Design was used for the sampling in two mango orchards, Arjo and Bako.  Scale population peaked in April at Arjo and in May at Bako showed marked decline with decreasing precipitation. Abundances of eggs, crawlers and sessile stages of the scale showed significant differences among most of the study months (P0.05). The abundance of sessile scales was significantly higher at Bako than at Arjo (P0.05). In both study areas, white mango scales were significantly more abundant on the upper leaf surfaces than the lower (P0.05). At Bako, male scale numbers were significantly higher than those of the females (P0.05). The study found that the decline and build-up of white mango scale populations are affected by rainfall, whereas the effects of other environmental factors on scale numbers need to be investigated. Key words: Developmental stages, fluctuation, infestation, orchard, rainfall, sessile. &nbsp

Geographic divergence in upper thermal limits across insect life stages: does behavior matter?

Insects with complex life cycles vary in size, mobility, and thermal ecology across life stages. We examine how differences in the capacity for thermoregulatory behavior influence geographic differences in physiological heat tolerance among egg and adult Colias butterflies. Colias adults exhibit differences in morphology (wing melanin and thoracic setal length) along spatial gradients, whereas eggs are morphologically indistinguishable. Here we compare Colias eriphyle eggs and adults from two elevations and Colias meadii from a high elevation. Hatching success and egg development time of C. eriphyle eggs did not differ significantly with the elevation of origin. Egg survival declined in response to heat-shock temperatures above 38-40 °C and egg development time was shortest at intermediate heat-shock temperatures of 33-38 °C. Laboratory experiments with adults showed survival in response to heat shock was significantly greater for Colias from higher than from lower elevation sites. Common-garden experiments at the low-elevation field site showed that C. meadii adults initiated heat-avoidance and over-heating behaviors significantly earlier in the day than C. eriphyle. Our study demonstrates the importance of examining thermal tolerances across life stages. Our findings are inconsistent with the hypothesis that thermoregulatory behavior inhibits the geographic divergence of physiological traits in mobile stages, and suggest that sessile stages may evolve similar heat tolerances in different environments due to microclimatic variability or evolutionary constraints.

Changes in physiological properties of bacteriophage-insensitive Staphylococcus aureus

This study was designed to assess the physiological properties of bacteriophage-insensitive Staphylococcus aureus (BISA) mutants, comparing lytic activity, antibiotic susceptibility, gene expression, sessile-forming ability, and sessile cell stability. Wild-type S. aureus (WTSA) was used to isolate BISA mutants against bacteriophage SA11 by the agar plate method. BISA mutants varied in their bacteriophage specificity and antibiotic susceptibility. The highest resistance to bacteriophage SA11 was observed in BISA4, followed by BISA3, BISA2, and BISA1. Enhanced bacteriophage resistance was stable in BISA2, BISA3, and BISA4 during the 24-h incubation period at 37 °C. The adhesion-related genes (clfA, clfB, eno, fib, and fnbB) were up-regulated in all BISA mutants, which correlated well with the sessile-forming ability but not the stability of sessile cells. This study provides new insights into the diversity in phenotypic and molecular properties of bacteriophage-resistant S. aureus during the planktonic-to-sessile transition and mature sessile stages.

Ultrastructure of the ciliated cells of the free-swimming larva, and sessile stages, of the marine spongeHaliclona indistincta(Demospongiae: haplosclerida)

We provide a detailed, comparative study of the ciliated cells of the marine haplosclerid sponge Haliclona indistincta, in order to make data available for future phylogenetic comparisons at the ultrastructural level. Our study focuses on the description and analysis of the larval epithelial cells, and choanocytes of the metamorphosed juvenile sponge. The ultrastructure of the two cell types is sufficiently different to prevent our ability to conclusively determine the origin of the choanocytes from the larval ciliated cells. However, ciliated, epithelial cells were observed in a migratory position within the inner cell mass of the larval stages. Some cilia were observed within the cell's cytoplasm, which is indicative of the ciliated epithelial cell undergoing transdifferentiation into a choanocyte; while traces of other ciliated epithelial cells were contained within phagosomes, suggesting they are phagocytosed. We compared our data with other species described in the literature. However, any phylogenetic inference must wait until further detailed comparisons can be made with species whose phylogenetic position has been determined by other means, such as phylogenomics, in order to more closely link genomic, and morphological information.

Seasonal Phenology of Pseudococcus maritimus (Hemiptera: Pseudococcidae) and Pheromone-Baited Trap Survey of Four Important Mealybug Species in Three Wine Grape Growing Regions of Oregon

Abstract Grape mealybug, Pseudococcus maritimus (Ehrhorn) (Hemiptera: Pseudococcidae), is a pest of grape vines, Vitis vinifera (Vitales: Vitaceae) and a known vector of several strains of grapevine leafroll-associated virus. Seasonal increase and decline of Ps. maritimus populations on wine grapes is described in each of three important grape growing regions in Oregon using pheromonebaited traps and visual monitoring. Delta traps and genomic verification of collected sessile stages found that only Ps. maritimus is present in Oregon vineyards. Seasonal pheromone-baited trapping and visual surveys during 2010 and 2011 identified two population peaks for adult male flight and sessile developmental stages on vines in Southern Oregon and the Columbia Basin. Willamette Valley vineyards identified one peak male flight period using pheromone-baited traps but no sessile individuals were found in visual surveys. Seasonal developmental stages are described for Southern Oregon and the Columbia Basin. First instar stages generally were observed one month before peak male flight and were less abundant during peak flight. Adult females and late instar stages were found on vines at the peak of male flight. Pheromone monitoring identified the presence of mealybug populations in viticultural areas, even when intensive visual surveys were unable to do so.

Traveling waves in discrete models of biological populations with sessile stages

A common approach to describing invasions of non-native species into previously unoccupied habitat is to consider the speed of population expansion and the existence of traveling waves. Typical existence theorems for traveling waves require some compactness properties of the next-generation operator. Many realistic modeling assumptions, however, give rise to non-compact operators; for example the occurrence of sessile stages during the life cycle of an individual. Recent results have extended the existence theory of traveling waves to a large class of weakly compact operators, but conditions can be difficult to check and not easily accessible to theoretical ecologists. In this paper, we give a new proof for the existence of traveling waves in a large class of equations where the next generation operator is not compact, but rather the sum of an integral operator and a contraction. We illustrate our proof with a model for the dispersal of a plant species with a seed-bank and a model for dispersal of stream insects with larval stages.

Expression of calmodulin and myosin light chain kinase during larval settlement of the Barnacle Balanus amphitrite.

Barnacles are one of the most common organisms in intertidal areas. Their life cycle includes seven free-swimming larval stages and sessile juvenile and adult stages. The transition from the swimming to the sessile stages, referred to as larval settlement, is crucial for their survivor success and subsequent population distribution. In this study, we focused on the involvement of calmodulin (CaM) and its binding proteins in the larval settlement of the barnacle, Balanus ( = Amphibalanus) amphitrite. The full length of CaM gene was cloned from stage II nauplii of B. amphitrite (referred to as Ba-CaM), encoding 149 amino acid residues that share a high similarity with published CaMs in other organisms. Quantitative real-time PCR showed that Ba-CaM was highly expressed in cyprids, the stage at which swimming larvae are competent to attach and undergo metamorphosis. In situ hybridization revealed that the expressed Ba-CaM gene was localized in compound eyes, posterior ganglion and cement glands, all of which may have essential functions during larval settlement. Larval settlement assays showed that both the CaM inhibitor compound 48/80 and the CaM-dependent myosin light chain kinase (MLCK) inhibitor ML-7 effectively blocked barnacle larval settlement, whereas Ca2+/CaM-dependent kinase II (CaMKII) inhibitors did not show any clear effects. The subsequent real-time PCR assay showed a higher expression level of Ba-MLCK gene in larval stages than in adults, suggesting an important role of Ba-MLCK gene in larval development and competency. Overall, the results suggest that CaM and CaM-dependent MLCK function during larval settlement of B. amphitrite.

Comparative myoanatomy of cycliophoran life cycle stages

The metazoan phylum Cycliophora includes small cryptic epibionts that live attached to the mouthparts of clawed lobsters. The life cycle is complex, with alternating sexual and asexual generations, and involves several sessile and free-living stages. So far, the morphological and genetic characterization of cycliophorans has been unable to clarify the phylogenetic position of the phylum. In this study, we add new details on the muscular anatomy of the feeding stage, the attached Prometheus larva, the dwarf male, and the female of one of the two hitherto described species, Symbion pandora. The musculature of the feeding stage is composed of myofibers that run longitudinally in the buccal funnel (two fibers) and in the trunk (variable number of fibers). The mouth opening is lined by a myoepithelial ring musculature. A complex myoepithelial sphincter is situated proximal to the anus. In the attached Prometheus larva, three longitudinal sets of myofilaments run dorsally, laterally, and ventrally along the entire anterior-posterior body axis. The muscular architecture of the dwarf male is complex, especially close to the penis, in the posterior part of the body. An X-shaped muscle structure is found on the dorsal side, whereas on the ventral side, longitudinal muscles and a V-shaped muscle structure are present. These muscles are complemented by additional dorsoventral muscles. The mesodermal muscle fibers attach to the cuticle via the epidermis in all life cycle stages studied herein. The musculature of the female is similar to that of the Pandora larva of Symbion americanus and includes dorsoventral muscles and longitudinal muscles that run in the dorsal and ventral body region. Overall, our results reveal striking similarities in the muscular arrangement of the life cycle stages of both Symbion species.

Ecosystem services related to oyster restoration

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 341:303-307 (2007) - doi:10.3354/meps341303 Ecosystem services related to oyster restoration Loren D. Coen1,*, Robert D. Brumbaugh2,**, David Bushek3, Ray Grizzle4, Mark W. Luckenbach5, Martin H. Posey6, Sean P. Powers7, S. Gregory Tolley8 1South Carolina Department of Natural Resources, Marine Resources Research Institute, 217 Fort Johnson Road, Charleston, South Carolina 29412, USA 2The Nature Conservancy, University of Rhode Island, Narragansett Bay Campus, South Ferry Road, Narragansett, Rhode Island 02882-1197, USA 3Haskin Shellfish Research Laboratory, Rutgers University, 6959 Miller Avenue, Port Norris, New Jersey 08349, USA 4Jackson Estuarine Laboratory, University of New Hampshire, 85 Adams Point Road, Durham, New Hampshire 03824, USA 5Virginia Institute of Marine Sciences, College of William and Mary, PO Box 350, Wachapreague, Virginia 23480, USA 6Department of Biology and Marine Biology, University of North Carolina, 601 S. College Road, Wilmington, North Carolina 28403, USA 7Department of Marine Sciences, University of South Alabama, and Dauphin Island Sea Lab, 101 Bienville Blvd, Dauphin Island, Alabama 36528, USA 8Florida Gulf Coast University, Coastal Watershed Institute, 10501 FGCU Blvd South, Fort Myers, Florida 33965, USA *Email: coenl@dnr.sc.gov**Authors after Coen in alphabetical order ABSTRACT: The importance of restoring filter-feeders, such as the Eastern oyster Crassostrea virginica, to mitigate the effects of eutrophication (e.g. in Chesapeake Bay) is currently under debate. The argument that bivalve molluscs alone cannot control phytoplankton blooms and reduce hypoxia oversimplifies a more complex issue, namely that ecosystem engineering species make manifold contributions to ecosystem services. Although further discussion and research leading to a more complete understanding is required, oysters and other molluscs (e.g. mussels) in estuarine ecosystems provide services far beyond the mere top-down control of phytoplankton blooms, such as (1) seston filtration, (2) benthic–pelagic coupling, (3) creation of refugia from predation, (4) creation of feeding habitat for juveniles and adults of mobile species, and for sessile stages of species that attach to molluscan shells, and (5) provision of nesting habitat. KEY WORDS: Crassostrea virginica · Restoration · Chesapeake Bay · Filter-feeders · Water quality · Ecosystem services Full text in pdf format PreviousExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 341. Online publication date: July 04, 2007 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2007 Inter-Research.

HOW DO LADYBIRDS [COLEOMEGILLA MACULATA LENGI (COLEOPTERA: COCCINELLIDAE)] FEED ON GREEN LACEWING EGGS [CHRYSOPERLA RUFILABRIS (NEUROPTERA: CHRYSOPIDAE)

Intraguild predation, a common interaction among arthropods (Polis et al. 1989), has been investigated recently in aphidophages (Rosenheim et al. 1993; Lucas et al. 1998). Sessile stages of coccinellids, gall midges, and lacewings (eggs, moulting individuals, and pupae) were shown to be highly vulnerable to intraguild predators (Lucas et al. 1998). Several defensive mechanisms have already been described for eggs of aphidophages, including chemical protection (Eisner et al. 1996), structural protection (Canard and Duelli 1984), and behavioural avoidance through the selection by females of protected oviposition sites (E. Lucas, and J. Brodeur, unpublished data).

Stylet penetration by larvae of the greenhouse whitefly on cucumber

AbstractProbing behaviour of Trialeurodes vaporariorum (Westwood) larvae was monitored using the DC electrical penetration graph (EPG) technique on the host plant cucumber. EPGs were recorded for 16 h, simultaneously with honeydew excretion using a ‘honeydew clock’. Three waveforms were distinguished: a pathway waveform (C), and two phloem waveforms, one with a high (H), and one with a low frequency (L) signal. The C waveform mainly occurred in the crawler stage of the 1st instar larvae. EPGs recorded from larvae during and after moulting indicated that the process involves stylet withdrawal; hence the stylets of each new instar need to penetrate again from the leaf surface to the phloem.All sessile stages, from L1 to pre‐pupa, spent almost their entire time in waveforms H and L. These waveforms alternated more frequently in the early instars than during the later ones, in which the H waveform became predominant. The H waveform was highly correlated with honeydew excretion and thus phloem sap ingestion. The L waveform was not related to honeydew excretion but EPGs indicated that the stylet tips remain in a sieve element during both waveforms. Periods of honeydew production demonstrated a delay of 30–40 min in relation to the onset and end of H and L waveforms. This delay is presumably related to the time needed for food passing through, or emptying of, the insect's gut. From the 1st instar to the pre‐pupa, the frequency of excreted honeydew droplets decreased but their size increased, causing a net increase of the excretion rate.

Cycliophora is a new phylum with affinities to Entoprocta and Ectoprocta

THE mouthparts of the Norway lobster Nephrops are colonized by an acoelomate metazoan, Symbion pandora gen. et sp. nov. Sessile stages continually produce inner buds replacing feeding structures. They also produce one of three motile stages: (1) larvae containing new feeding stages, (2) dwarf males, which settle on feeding stages, or (3) females, which settle onto lobster mouthparts, and eventually degenerate, giving rise to dispersive larvae. All motile stages are short-lived, and do not feed. The structure and function of the cilia suggest a phylogenetic position in Protostomia, while some aspects of inner budding and brooding of larvae are similar to those of Entoprocta and Ectoprocta. The dispersive larva possesses a mesodermal supporting chordoid structure, otherwise absent in protostomian larvae. We believe that all the above features of this previously undescribed species warrant the recognition of a new phylum with affinities to Ectoprocta and Entoprocta.

Forecasting the Abundance of the Sea Nettle, Chrysaora quinquecirrha, in the Chesapeake Bay

The sea nettle shows variable seasonal infestation in the Chesapeake Bay. Public interest in the medusal population prompted an examination of the effect of climatic, hydrographic, and biological variables on such changes. Visual medusal counts since 1960 were regressed in a stepwise fashion against the suite of variables, to produce an abundance model which allows a reasonable prediction of the forthcoming summer’s infestation. Streamflow in the entire Chesapeake watershed for the months of January through June and the water temperature for May were most important. Lower streamflow apparently provides a salinity regime which supports the sessile stages early in the year and allows the survival and rapid growth of ephyrae in early summer. The water temperatures in May furnishes the trigger for strobilation at a propitious time.

Armored Scale Control with Non-Oil Scalecides, 1977

Abstract Two rates each of SD 43775 and Imidan were compared to Supracide for scale control on Marrs Early orange trees. Treatments were completely randomized and replicated three times in single-tree plots. Applications were made using a 2 gal Hudson Sprayer with CO2 at 80 psi as a spray propellent. Spray was applied until runoff, with an area of ca. 2 square meters sprayed in each tree. Treatments were made on Aug 3’77, with scale mortality counts of both crawler and sessile stages at 2 and 6 weeks posttreatment. At each count, 8-10 terminals consisting of twigs, leaves and fruit were sampled from the treated areas in each tree and examined for scale under a binocular microscope. Any mortality from parasitism, chiefly by Aphytis sp., was recorded and subtracted from mortality due to the scalecide treatment.

Population Dynamics of Two Gorgonian Corals

The gorgonian corals Muricea calofirnica and Muricea fruticosa, co—occur at shallow depths along the western coasts of the Americas. Their northern geographic limit is Point Conception in California; the southern limits are unknown but may be Peru. In California, the depth range of both species is 1—30 m. Their abundances range up to 7.90 and 2.35 colonies/m2, respectively. Both species spawn once each year at a time which corresponds to annual peak temperature, which corresponds to annual peak temperature, which in California occurs later in the year for deeper segments of the population. Depth—staggered spawning has the effect of extending its duration from 2 to about 6 mo. During the larval stages of both species, mortality rates are low and nearly constant. Field records that detachment and abrasion rather than predation are the major sources of mortality for sessile stages. Several lines of evidence suggest that recruitment is generally spaced limited. In habitats where space is fully occupied, space limitation may regulate recruitment. In such habitats recruitment and mortality of populations of Muricea are nearly constant (i.e. in steady state), and their actual rates of natural increase are close to zero. In contrast, intrinsic rates of natural increase (rmax) are very high: 0.92 for M. californica and 1.45 for M. fruitcosa. These enormous rates of potential increase are offset by high rates of larval mortality in the plankton. Although M. californica is significantly more longevous than M. fruticosa, both species share similar patterns of life history. Competition for settlement and living space rarely occurs between the two species rather, it often takes place with other plants and invertebrates. These interactions may be sufficiently unpredictable for either species of Muricea to develop a competitive advantage over the other and hence may explain their coexistence. Thus, in the absence of significant direct competition between the two species, their similarities in life history may simply represent similar adaptations to the same set of environmental variables. Both species exhibit life history correlates of both K—selection (iteroparity, delayed reproduction, and relative great longevity) and r—selection (high (rmax). Life history at tributes of a single species may be located at different points along the r—K continuum. In fact, their colonial habit allows for combination of good characteristics of both patterns of selection and may be explain the evolutionary success of this type of life history, phenomena.

Notes on the Biology of the Sea Nettle, Chrysaora quinquecirrha, in Chesapeake Bay

Despite the continuous nuisance value of the sea nettle in Chesapeake Bay, the only major report on the biology of this species was that of the laboratory studies by Littleford in 1939. Therefore, we began a study of the biology ofChrysaora quinquecirrha aimed at increasing the understanding of its life history which had not been investigated. The occurrence of sessile stages on the under-sides of a variety of substrates, especially oyster shells, is reported for the first time. The geographic range of the polyp stage in Chesapeake Bay is partially delineated with respect to depth (<11 m) and salinity (5%.–19%.). Sampling for ephyrae near Solomons, Maryland suggested that strobilation began in April and extended into August. The growth of medusae was rapid, and their feeding appeared opportunistic and frequent.