Ultrastructural observations on prey capture and digestion in the scyphomedusa Aurelia aurita

Heeger, Thomas; Möller, H.

doi:10.1007/bf00412523

Cited by 58 publications

(48 citation statements)

References 16 publications

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“…Previous studies using scanning electron micrographs of preserved samples of nematocysts on captured prey have repeatedly found euryteles and O-isorhizas of scyphomedusa to penetrate both hard and soft bodied prey for the full length of their tubule (Heeger and Möller, 1987;Heeger et al, 1992;Östman and Hydman, 1997;Peach and Pitt, 2005). In contrast, a-isorhizas are less effective penetrants (Heeger and Möller, 1987;Peach and Pitt, 2005) and have been found to only partially penetrate their prey, leaving the rest of their tubule to stick to the surface of the prey (Heeger and Möller, 1987). This observation is consistent with their lower discharge velocities and kinetic energies.…”

Section: Discussionmentioning

confidence: 99%

“…For example, isorhizas, the most common nematocyst type within the phylum Cnidaria, are identified by their uniform tubule diameter (Östman, 2000) and are generally described as penetrating nematocysts (Purcell and Mills, 1988;Östman and Hydman, 1997;Heeger and Möller, 1987;Heeger et al, 1992). Although C. capillata's three isorhizas were characterized by similar tubule diameters, their dynamic traits differed dramatically.…”

Section: Discussionmentioning

confidence: 99%

“…The majority of described nematocyst types are assumed to be penetrants because the tip of their tubules are open and are inferred to be capable of delivering the toxins characterizing cnidarian stings. Beyond this, most of our current knowledge on prey capture by nematocysts is based upon studies which either relate the nematocyst assemblage found on a medusan species to its diet (Purcell and Mills, 1988;Carrette et al, 2002;Peach and Pitt, 2005), or studies using microscopy to examine preserved samples of nematocysts and their captured prey (Purcell, 1984;Heeger and Möller, 1987;Heeger et al, 1992;Östman and Hydman, 1997;Peach and Pitt, 2005). Due to the inherent difficulty in observing the fastest cellular process identified, few studies have directly observed and described the discharge properties of different types of nematocysts (Holstein and Tardent, 1984;Nuchter et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, we do not know whether the tubules of similar types of nematocysts discharge similarly or whether their discharge properties are related to the nematocyst categories identified by taxonomists. Since tubules are the part of nematocysts typically observed clinging to prey (Purcell, 1984;Heeger and Möller, 1987;Heeger et al, 1992;Östman and Hydman, 1997;Peach and Pitt, 2005), their properties likely determine how nematocysts capture prey, and hence, their functions.…”

Section: Introductionmentioning

confidence: 99%

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Functional characteristics of nematocysts found on the scyphomedusa Cyanea capillata

Colin

Costello

2007

Journal of Experimental Marine Biology and Ecology

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Although prey capture by cnidarians is mediated through nematocysts, their influence on prey selection by cnidarians remains poorly documented. The difficulty in visualizing nematocyst-prey interactions remains the chief obstacle to understanding how the wide variety of nematocyst types influences the mechanics of prey capture. One solution to this limitation has been to assign functional roles to nematocysts based on morphological characters of discharged cnidae. Here we report results of an alternative approach based upon dynamic traits of nematocyst discharge. We examined tubule lengths, tubule discharge velocities and net-togross displacement ratios of tubules of discharging nematocysts possessed by the cosmopolitan scyphomedusa, Cyanea capillata. This nematocyst assemblage consisted of euryteles, birhopaloids and three different isorhizas -a-isorhizas, A-isorhizas and Oisorhizas. Dynamic traits varied little within each nematocyst type but there were significant differences between the different types. Most importantly, dynamic traits varied significantly within a broad category of nematocyst -the isorhizas -indicating that conventional classification schemes that infer function based on broad nematocyst categories may not appropriately describe the functional roles of these nematocysts. The dynamic properties of discharging nematocysts were consistent with physical results described in studies using scanning electron microscopy images of nematocyst-prey interactions. These data suggest that nematocysts vary significantly in their roles during predation, but that inferences relating prey selection with broad nematocyst categories merit careful examination.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Functional characteristics of nematocysts found on the scyphomedusa Cyanea capillata

Colin

Costello

2007

Journal of Experimental Marine Biology and Ecology

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“…However, studies conducted by Costello & Colin (1994 suggested that the use of umbrella pulsation-induced flow for prey entrainment and capture is widespread among the scyphomedusae, and therefore the traditional views of scyphozoan prey capture needed to be revised to include consideration of fluid motion around swimming medusae as well as prey escape responses. Until then, the subumbrellar surface (Southward 1955b), the exumbrellar surface (Bailey & Batty 1983) and the tentacles (Fraser 1969, Heeger & Möller 1987 had been identified as the primary body surface used to capture prey, mainly mesozooplankton, but also fish larvae, hydromedusae, and microzooplankton (e.g. Heeger & Möller 1987, Stoecker et al 1987, Båmstedt 1990.…”

Section: Scyphomedusaementioning

confidence: 99%

Particle capture mechanisms in suspension-feeding invertebrates

Riisgård¹,

Larsen²

2010

Mar. Ecol. Prog. Ser.

214

179

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A large number of suspension-feeding aquatic animals (e.g. bivalves, polychaetes, ascidians, bryozoans, crustaceans, sponges, echinoderms, cnidarians) have specialized in grazing on not only the 2 to 200 µm phytoplankton but frequently also the 0.5 to 2 µm free-living bacteria, or they have specialized in capturing larger prey, e.g. zooplankton organisms. We review the different particle capture mechanisms in order to illustrate the many solutions to the common problem of obtaining nourishment from a dilute suspension of microscopic food particles. Despite the many differences in morphology and living conditions, particle capture mechanisms may be divided into 2 main types. (1) Filtering or sieving (e.g. through mucus nets, stiff cilia, filter setae), which is found in passive suspension feeders that rely on external currents to bring suspended particles to the filter, and in active suspension feeders that themselves produce a feeding flow by a variety of pump systems. Here the inventiveness of nature does not lie in the capture mechanism but in the type of pump system and filter pore-size. (2) A paddle-like flow manipulating system (e.g. cilia, cirri, tentacles, hair-bearing appendages) that acts to redirect an approaching suspended particle, often along with a surrounding 'fluid parcel', to a strategic location for arrest or further transport. Examples include (1) sieving (e.g. by microvilli in sponge choanocytes, mucus nets in polychaetes, acidians, and salps among others), filter setae in crustaceans, 'ciliary sieving' by stiff laterofrontal cilia in bryozoans and phoronids; and (2) 'cirri trapping' in mussels and other bivalves with eu-laterofrontal cirri, ciliary 'catch-up' in bivalve and gastropod veliger larvae, some polychaetes, entroprocts, and cycliophores. These capture mechanisms may involve contact with a particle, and possibly mechanoreception or chemoreception, or may include redirection of particles by the interaction of multiple currents (e.g. in scallops and other bivalves without eu-laterofrontal cirri). Based on the review, we discuss the current physical and biological understanding of the capture process and suggest a number of specific problems related to particle capture, which may be solved in the future using advanced theoretical, computational and experimental techniques.

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Nematocysts of Rhopilema nomadica (Scyphozoa: Rhizostomeae), an immigrant jellyfish in the eastern mediterranean

Avian

Spanier

Galil

1995

Journal of Morphology

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Rhopilema nomadica-a recently discovered scyphomedusa in the eastern Mediterranean-is considered a lessepsian migrant. Its nematocysts were extracted from the scapular and mouth-arm tentacles and examined using light and electron microscopy techniques. The morphometric parameters of the nematocysts were measured before and after complete discharge. Three categories of nematocysts were identified: heterotrichous isorhiza haploneme, holotrichous isorhiza haploneme, and heterotrichous microbasic eurytele. The relative abundance of the nematocysts and their occurrence in tissues of the jellyfish were noted. A brief discussion concerning the classification of certain types of nematocysts is given. A comparison with the available data on other Rhopilema species revealed that the nematocyst categories of R. nomadica are more similar to those of the Atlantic R. verrilli than to those of the Western Pacific R. esculentum. A brief comparison of the injuries caused by these species is given. © 1995 Wiley-Liss, Inc.

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Ultrastructural observations on prey capture and digestion in the scyphomedusa Aurelia aurita

Cited by 58 publications

References 16 publications

Functional characteristics of nematocysts found on the scyphomedusa Cyanea capillata

Functional characteristics of nematocysts found on the scyphomedusa Cyanea capillata

Particle capture mechanisms in suspension-feeding invertebrates

Nematocysts of Rhopilema nomadica (Scyphozoa: Rhizostomeae), an immigrant jellyfish in the eastern mediterranean

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