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

Thiel, Martín; Dernedde, T.

doi:10.1007/bf02367108

“…In this study, only one or a small number of fully differentiated oocytes typically fills the ovarian lumen of benthic and pelagic enoplans. However, Thiel and Dernedde (1996) report that up to 10 mature eggs can occur in an ovary of the enoplan Amphiporus lactifloreus. Moreover, some anoplan species examined in this study (e.g.…”

Section: Intraovarian Development Of Oocytes: Vitellogenesis and Nuclmentioning

confidence: 99%

“…However, some benthic nemerteans are: (1) iteroparous forms that live for more than one year [e.g. Paranemertes peregrina ( Roe 1976) and Amphiporus lactifloreus ( Thiel and Dernedde 1996) ];…”

Section: Intraovarian Development Of Oocytes: Vitellogenesis and Nuclmentioning

confidence: 99%

Comparative biology of oogenesis in nemertean worms

Stricker¹,

Smythe²,

Miller³

et al. 2000

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In order to supplement previous analyses of oogenesis in nemertean worms, this study uses light and electron microscopy to compare the ovaries and oocytes in 16 species of nemerteans that represent various taxa within the phylum, Nemertean ovaries comprise serially repeated sacs with an ovarian wall that characteristically includes myofilament-containing cells interspersed among the germinal epithelium. Each oocyte can attach to the germinal epithelium by a vegetally situated stalk and resides in the ovarian lumen without being surrounded by follicle cells. In the ovary, oocytes arrest at prophase I of meiosis and contain a hypertrophied nucleus ('germinal vesicle') that often possesses multiple nucleoli. Intraovarian growth apparently involves an autosynthetic mode of yolk formation in most nemerteans and generates oocytes that measure ~60 Jim to 1 mm. When fully developed, oocytes can be discharged through a short gonoduct and are either spawned freely or deposited within egg cases. In most species, oocytes released from the ovary possess extracellular coats and resume maturation by undergoing germinal vesicle breakdown (GVBD). Such post-GVBD specimens also form a punctate endoplasmic reticulum that may facilitate fertilization and development.

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“…However, some benthic nemerteans are: (1) iteroparous forms that live for more than one year [e.g. Paranemertes peregrina (Roe 1976) and Amphiporus lactifloreus (Thiel and Dernedde 1996)]; (2) sexually reproductive during late autumn [e.g. Amphiporus lactifloreus (Thiel and Dernedde 1996)] or throughout much of the year [e.g.…”

Section: Discussionmentioning

confidence: 99%

“…Paranemertes peregrina (Roe 1976) and Amphiporus lactifloreus (Thiel and Dernedde 1996)]; (2) sexually reproductive during late autumn [e.g. Amphiporus lactifloreus (Thiel and Dernedde 1996)] or throughout much of the year [e.g. Malacobdella grossa (Gibson 1968)]; and/or (3) capable of undergoing asexual reproduction throughout the year with some periods of sexual reproduction during winter [ Lineus vegetus (Coe 1931), see also Riser (1994)].…”

Section: Discussionmentioning

confidence: 99%

Comparative biology of oogenesis in nemertean worms

Stricker

¹

,

Smythe

²

,

Miller

³

et al. 2001

View full text Add to dashboard Cite

In order to supplement previous analyses of oogenesis in nemertean worms, this study uses light and electron microscopy to compare the ovaries and oocytes in 16 species of nemerteans that represent various taxa within the phylum, Nemertean ovaries comprise serially repeated sacs with an ovarian wall that characteristically includes myofilament-containing cells interspersed among the germinal epithelium. Each oocyte can attach to the germinal epithelium by a vegetally situated stalk and resides in the ovarian lumen without being surrounded by follicle cells. In the ovary, oocytes arrest at prophase I of meiosis and contain a hypertrophied nucleus ('germinal vesicle') that often possesses multiple nucleoli. Intraovarian growth apparently involves an autosynthetic mode of yolk formation in most nemerteans and generates oocytes that measure ~60 Jim to 1 mm. When fully developed, oocytes can be discharged through a short gonoduct and are either spawned freely or deposited within egg cases. In most species, oocytes released from the ovary possess extracellular coats and resume maturation by undergoing germinal vesicle breakdown (GVBD). Such post-GVBD specimens also form a punctate endoplasmic reticulum that may facilitate fertilization and development.

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“…Roe 1979aRoe , 1986Wickham 1980;Kuris 1993;Santos et al 2006). Of the free-living nemerteans, data on aspects of the life cycle are available for Paranemertes peregrina Coe, 1901 (Roe 1970(Roe , 1976(Roe , 1979b, Amphiporus lactifloreus (Johnston, 1828) (Thiel and Dernedde, 1996), Tetrastemma fozensis Gibson &Junoy, 1991 (Thiel andZubillaga 1998), and Lineus ruber (Müller, 1774) (Gontcharoff 1951(Gontcharoff , 1960Bierne 1970;Vernet and Bierne 1993).…”

Section: Introductionmentioning

confidence: 99%

Life history of Lineus viridis (Müller, 1774) (Heteronemertea, Nemertea)

Döhren

¹

,

Beckers

²

,

Bartolomaeus

³

2011

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Lineus viridis is a common nemertean species of North-Atlantic intertidal sand flats. Its mating behaviour is peculiar insofar as this species is reported to be polyandric. However, detailed information on this topic is lacking. In order to get more data on the reproduction, oogenesis and life history of this species, a population in the Wadden Sea on the Isle of Sylt (North Sea) was studied between 2005 and 2011. We conducted regular surveys, during which we sampled, measured and recorded the sex status of 25-100 individuals at each sampling event; at least three individuals were fixed for histological studies at each sampling date. In addition, animals were kept in the laboratory for 3 years to complement field data on sexual identity. Lineus viridis was found to reproduce annually in several successive year; the females are significantly larger than the males. Oogenesis starts in spring, shortly after the preceding reproductive period, and continues until the end of December. Spermiogenesis starts in late autumn and also ends late in December. During mating, several males are generally found crawling on a single female, which forms a cocoon that encloses both the female and the associated males. Fertilization is internal. While females discharge all of their eggs during a single mating event and lose more than 40% of their wet weight, males only empty a few of their gonads, and are thus able to fertilize more than one female. Our study clearly shows that Lineus viridis is a perennial, iteroparous species with a pronounced sexual size dimorphism. During this long-term study, no evidence for sequential hermaphroditism has been found. The observed polyandric mating system in this species raises further questions regarding mate and sperm competition that deserve additional research.

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

Cited by 10 publications

References 23 publications

Comparative biology of oogenesis in nemertean worms

Comparative biology of oogenesis in nemertean worms

Comparative biology of oogenesis in nemertean worms

Life history of Lineus viridis (Müller, 1774) (Heteronemertea, Nemertea)

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