Observations on the Nutrition of Seven Species of Rhynchocoelan Worms

Jennings, J. B.; Gibson, Ray

doi:10.2307/1539685

Cited by 77 publications

(99 citation statements)

References 20 publications

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“…This nemertean only paralyzes its prey prior to ingestion, unlike N. p&her and other suctorial hoplonemerteans that we have studied to date, which kill the prey (McDermott, 1976(McDermott, , 1984McDermott & Snyder, 1988). This is probably the case for other suctorial hoplonemerteans studied by Jennings & Gibson (1969) and Bartsch (1973), although not demonstrated experimentally. Amphiporus anguZatus, a suctorial species, contains many bipyridyl and tetrapyridyl alkaloids, and the major one, 2,3 ' -bipyridyl, appears to be a more powerful toxin than anabaseine (Kern et al, 1976).…”

Section: Discussionmentioning

confidence: 57%

“…A somewhat parallel situation may exist in seagrass communities where hoplonemerteans must have some influence on the variety of amphipod populations, and this in turn may affect the populations of fishes and decapod crustaceans that also depend on amphipod and isopods as important food sources (McDermott, 1988). There is some evidence that certain nemerteans feed on other nemerteans (Jennings & Gibson, 1969;Cantell, 1975), and also evidence that nemerteans may be prey for a variety of other animals (McDermott & Roe, 1985). Fish, and particularly flatfish, may possibly be amongst the most important predators.…”

Section: Discussionmentioning

confidence: 99%

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Nemertea inhabiting the Haploops (Amphipoda) community of the northern Øresund with special reference to the biology of Nipponnemertes pulcher (Hoplonemertea)

McDermott

1993

Hydrobiologia

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The densities of nemerteans and associated fauna on a soft-bottom sampling station (27-30 m deep) in the 0resund were determined from 47 cores (each 135 cm2 in cross-section; 20 + cm deep) collected from September to December 1989; these data were compared with 14 cores taken from the same location in December 1982. Nine species of nemerteans were identified from cores and dredge samples: Palaeonemertea -Callinera-like sp.; Heteronemertea -Cerebratulus fuscus, C. marginatus, Lineus bilineatus, Micrura fasciolata, M. purpurea; Hoplonemertea -Amphiporus bioculatus, A. dissimulans, Nipponnemertes pulcher. Mean numbers of heteronemerteans were 32 and 10 rn-* in 1982 and 1989, respectively, and hoplonemerteans were 90 and 7 1 m-2, respectively. Only one palaeonemertean was collected during both years. Mean densities of the dominant species, N. pulcher, were similar for the two years, 74 and 68 m -*. The dominant groups of macrofauna (n rn-') in 1989 were ostracods (1028), amphipods (618), polychaetes (514), and ophiuroids (449). Amphipods (> 90% Huploops spp.) and polychaetes (at least 30 spp.) are the major potential prey for hoplonemerteans and heteronemerteans, respectively. Laboratory feeding experiments with N. pulcher revealed that it consumed amphipods (Haploops tenuis and H. tubicolu) at a rate of 2.6 worm-' d-' during the first 12 hours, but after 36 hours and beyond the rate was maintained at approximately 0.2 worm-I d-'. Beyond 12 hours this nemertean showed a tendancy to only partially evacuate its prey. It was demonstrated experimentally that N. pulcher has a supply of toxin capable of killing six amphipods in approximately one hour. Limited tests showed that N. pulcher fed on the cumacean Diastylis tumida, but not on the amphipod Maera loveni or the ostracod Philomedes globosus, and that Amphiporus dissimulans readily attacked Haploops spp., but not Maera or Philomedes. Although the results of laboratory experiments are tentative, they do suggest that suctorial hoplonemerteans can exert a potentially significant effect on benthic communities. Employing seven species of polychaetes as prey for Cerebratulus fuscus and Micrura fasciolata, only the latter responded positively to one of them, Glyceru alba. The hermit crab Pagurus bernhardus violently rejected N. pulcher in all feeding trials.

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Section: Discussionmentioning

confidence: 57%

Section: Discussionmentioning

confidence: 99%

Nemertea inhabiting the Haploops (Amphipoda) community of the northern Øresund with special reference to the biology of Nipponnemertes pulcher (Hoplonemertea)

McDermott

1993

Hydrobiologia

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“…The glandular epithelium of the proboscis contains a variety of secretory cells that synthesize products involved in subduing prey (Jennings and Gibson 1969;Stricker and Cloney 1983). These include cells that produce prey-immobilizing toxins (see Kem 1985;Stricker and Cloney 1983), those that secrete substances facilitating adhesion of prey to the proboscis (see Stricker and Cloney 1983), and those that elaborate rod-or club-shaped structures with an internal filament presumably involved in gripping prey (e.g.…”

Section: Introductionmentioning

confidence: 99%

Ultrastructure of the pseudocnidae of the palaeonemerteansCephalothrixcf.rufifronsandCarinomella lacteaand an assessment of their phylogenetic utility

Turbeville¹

2006

Journal of Natural History

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The ultrastructure of the pseudocnidae (filament-core rhabdoids) of the palaeonemerteans Cephalothrix cf. rufifrons and Carinomella lactea is described and the phylogenetic utility of these organelles evaluated. Pseudocnidae of Cephalothrix cf. rufifrons are clavate structures, measuring 3-5 mm in length with a bulbous lateral process present near their midregion, whereas those of Carinomella lactea are rod-shaped structures, measuring 2-3 mm in length and lack a lateral process. In both species, these structures exhibit a somewhat electron-lucent cortex, an electron-dense medulla and a distinct filament-like core, extending from the apex of the pseudocnida toward its base. The pseudocnidae are situated within pseudocnida-forming cells that constitute a portion of the glandular proboscis epithelium and are oriented parallel to the apical basal axis of the cell. No evidence of core extrusion was observed in these species. Comparative structural analyses confirm that these secretory granules are neither rhabdite homologues nor cleptocnidae. Position and ultrastructure of palaeonemertan pseudocnidae support the hypothesis that they are homologous to those of heteronemerteans, and pseudocnidae are interpreted as a provisional synapomorphy of the Anopla, as suggested in previous studies. However, recent molecular phylogenies of nemerteans do not support anoplan monophyly, necessitating alternative interpretations of pseudocnida evolution, namely, that these structures were present in the nemertean common ancestor and subsequently lost in the hoplonemerteans and Carinoma or that they evolved independently in the Pilidiophora and a Cephalothricidae+Tubulanidae clade. A rigorous explanation of pseudocnida evolution awaits a simultaneous analysis of molecular and morphological characters inclusive of pseudocnidae.

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“…It feeds preferentially on amphipods of the genus Gammarus (Jennings & Gibson, 1969;McDermott & Roe, 1985). A. lactifloreus can be found in aggregations comprising several intermingled individuals within mussel clumps.…”

Section: Life-history Of Amphiporus Lactifloreusmentioning

confidence: 99%

Reproduction ofAmphiporus lactifloreus (Hoplonemertini) on tidal flats: implications for studies on the population biology of nemertines

Thiel

Dernedde

1996

Helgolander Meeresunters

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The reproductive period and life-history parameters were investigated for the hoplonemertine Amphiporus lactifloreus found on the tidal flats of the island of Sylt in the northern Wadden Sea. Every six weeks 20 individuals were collected and then histologically examined to determine the development stage of their reproductive organs. A. lactifforeus reproduces in the late autumn, its peak reproduction being in the second half of November. Individuals from all size classes > 20 mm body length produced gametes. Individuals of the cohorts that reproduced in the late autumn of 1992 persisted and grew until July 1993, indicating that A. lactifloreus is an iteroparous species. The length of relaxed individuals was significantly correlated with their length under anaesthetized conditions, but the regression changed significantly after the reproductive period. Length under 'relaxed' conditions was significantly correlated with weight (wet weight, dry weight, and ash-free dry weight); these relationships did not vary significantly before or after the reproductive period. Our results show that important life-history data of intertidal nemertines can be obtained without time-consuming histological studies. On the basis of these findings, recommendations for future studies on the population biology of intertidal nemertines are given. Regular length measurements of nemertines under 'relaxed' conditions are proposed as a useful tool for tracking the growth and survival of annual cohorts of intertidal nemertines.

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Observations on the Nutrition of Seven Species of Rhynchocoelan Worms

Cited by 77 publications

References 20 publications

Nemertea inhabiting the Haploops (Amphipoda) community of the northern Øresund with special reference to the biology of Nipponnemertes pulcher (Hoplonemertea)

Nemertea inhabiting the Haploops (Amphipoda) community of the northern Øresund with special reference to the biology of Nipponnemertes pulcher (Hoplonemertea)

Ultrastructure of the pseudocnidae of the palaeonemerteansCephalothrixcf.rufifronsandCarinomella lacteaand an assessment of their phylogenetic utility

Reproduction ofAmphiporus lactifloreus (Hoplonemertini) on tidal flats: implications for studies on the population biology of nemertines

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