Microscopic anatomy, functional morphology, and ultrastructure of the stomach of Euphausia superba Dana (Crustacea, Euphausiacea)

Ullrich, Bernd; Storch, Völker; Marschall, H. P.

doi:10.1007/bf00240209

Cited by 25 publications

(31 citation statements)

References 20 publications

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“…Although a detailed study on the microscopic anatomy of the krill stomach exists (Ullrich et al 1991), histological and cytological investigations of the midgut gland of euphausiids are rare and there have been no such investigations for E. superba. The following explanation is, therefore, based on the well-characterized digestive tract of systematically closely related decapods.…”

Section: Discussionmentioning

confidence: 99%

“…In the anterior region of the stomach (cardia) the food is ground and mixed with digestive enzymes from the midgut gland. In the posterior part of the stomach (pylorus) the crushed food is ®ltered and the ®ltrate is passed on into the midgut gland (Ullrich et al 1991). The midgut gland consists of a system of blind-ending tubules which again consist of a unilayer epithelium with special cells for nutrient resorption (R-cells) and cells for enzyme synthesis (F-cells).…”

Section: Discussionmentioning

confidence: 99%

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A laboratory study on digestive processes in the Antarctic krill, Euphausia superba , with special regard to chitinolytic enzymes

Saborowski

Búchholz

1999

Polar Biology

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Feeding experiments of 9, 14 and 20 days duration were carried out on the Antarctic krill, Euphausia superba. Two groups were fed with the chitinous diatom Cyclotella cryptica and the non-chitinous green algae Dunaliella bioculata, respectively. A control group remained unfed. The time courses of the activities of endo-and exochitinase in the stomach and the midgut gland were compared with those of the digestive enzymes protease, cellulase (1,4-b-D-glucanase) and laminarinase (1,3-b-D-glucanase). Speci®c activities of all enzymes were higher in the stomach than in the midgut gland. Characteristic time courses of activity were evident after 4 days. In starved animals, enzyme activities decreased to a minimum after 4 days and recovered within 14 days to initial values. In the stomach, the activities of endo-and exochitinase increased when krill were fed on Cyclotella. For animals fed with Dunaliella, activities stayed constant or decreased slightly. The results con®rm chitinases as digestive enzymes and, therefore, the capability of krill to utilize various food sources.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

A laboratory study on digestive processes in the Antarctic krill, Euphausia superba , with special regard to chitinolytic enzymes

Saborowski

Búchholz

1999

Polar Biology

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“…Therefore feeding of early larval stages may differ from that of FIII stages as well as adult krill and might influence enzyme activity. The different trend in proteinase between larval stages could be explained either by differences in morphology of the gut (Ullrich et al 1991;Ullrich and Storch 1993), as suggested by differences in the equivalent protozoea and zoea of decapods (Williamson 1982), or alternatively by differences in food quantity or type between the summer and autumn studies. The main food source of furcilia larvae are microalgae and they show high ingestion and turnover rates when food is available .…”

Section: Digestive Enzyme Activitymentioning

confidence: 99%

Seasonal differences in citrate synthase and digestive enzyme activity in larval and postlarval antarctic krill, Euphausia superba

et al. 2002

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Antarctic krill maintain large population sizes despite dramatic seasonal fluctuations in food availability, but the mechanisms for this are still debated. The aim of this study was to compare seasonal differences in enzyme activity and respiration rates of larval and postlarval krill to provide insights into their overwintering strategies. Respiration rates, activity of the metabolic enzyme citrate synthase (CS), and those of the digestive enzymes laminarinase and total proteinase were measured in austral summer west of the Antarctic Peninsula, and in autumn in the southwestern Lazarev Sea. The 100-fold difference in chlorophyll a concentrations between the two studies is representative of the classic transition from a summer bloom to sparse winter conditions. Correspondingly, adult krill showed reduced respiration rates and CS activity in autumn. However, their digestive enzyme activity was significantly higher, suggesting more efficient assimilation of food at low food levels. Similar-sized larvae showed no summer-autumn differences in respiration rates and enzyme activity, supporting suggestions that they need to feed and grow year-round. However, trends in enzymatic activity varied between the larval stages measured, implying ontogenetic changes in body structure and function.

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“…The enzymes accumulate in the stomach. Food, which is ground in the stomach by the gastric mill (Ullrich et al, 1991), is simultaneously mixed with the digestive enzymes initializing the extracellular digestion of the food. The chyme is then pressed through a fine filter system which allows the liquid fraction to pass into the midgut gland for nutrient resorption but retains larger solid particles such as diatom frustles, copepod mouthparts, or cuticle fragments for defecation.…”

Section: The Digestive Organsmentioning

confidence: 99%

Physiology and Metabolism of Northern Krill (Meganyctiphanes norvegica Sars)

Spicer

Saborowski

2010

Advances in Marine Biology

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Microscopic anatomy, functional morphology, and ultrastructure of the stomach of Euphausia superba Dana (Crustacea, Euphausiacea)

Cited by 25 publications

References 20 publications

A laboratory study on digestive processes in the Antarctic krill, Euphausia superba , with special regard to chitinolytic enzymes

A laboratory study on digestive processes in the Antarctic krill, Euphausia superba , with special regard to chitinolytic enzymes

Seasonal differences in citrate synthase and digestive enzyme activity in larval and postlarval antarctic krill, Euphausia superba

Physiology and Metabolism of Northern Krill (Meganyctiphanes norvegica Sars)

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