The Reproductive Biology of Ophiacantha Bidentata (Echinodermata: Ophiuroidea) From The Rockall Trough

Author(s):  
P. A. Tyler ◽  
J. D. Gage

INTRODUCTIONOphiacantha bidentata (Retzius) is a widespread arctic-boreal ophiuroid with a circumpolar distribution in the shallow waters of the Arctic seas and penetrating into the deep sea of the.North Atlantic and North Pacific (Mortensen, 1927, 1933a; D'yakonov, 1954). Early observations of this species were confined to defining zoogeo-graphical and taxonomic criteria including the separation of deep water specimens as the variety fraterna (Farran, 1912; Grieg, 1921; Mortensen, 1933a). Mortensen (1910) and Thorson (1936, pp. 18–26) noted the large eggs (o.8 mm diameter) in specimens from Greenland and Thorson (1936) proposed that this species had ‘big eggs rich in yolk, shed directly into the sea. Much reduced larval stage or direct development’. This evidence is supported by observations of O. bidentata from the White and Barents Seas (Semenova, Mileikovsky & Nesis, 1964; Kaufman, 1974)..

1870 ◽  
Vol 18 (114-122) ◽  
pp. 59-62 ◽  

The Author commences by referring to the knowledge of the Rhizopodal Fauna of the Deep Sea which has been gradually acquired by the examination of specimens of the bottom brought up by the Sounding-apparatus; and states that whilst this method of investigation has made known the vast extent and diffusion of Foramimferal life at great depths,-especially in the case of Globigerina-mud , which has been proved to cover a large part of the bottom of the North Atlantic Ocean,—it has not added any new Generic types to those discoverable in comparatively shallow waters. With the exception of a few forms, which, like find their most congenial home, and attain their greatest development, at great depths, the general rule has seemed to be that Foramimfera are progressively dwarfed in proportion to increase of depth, as they are y a change from a warmer to a colder climate; those which are brought up from great depths in the Equatorial region bearing a much stronger resemblance to those of the colder-temperate, or even of the Arctic seas, than to the littoral forms of their own region.


Author(s):  
P. A. Tyler

SynopsisThe reproductive biology of a wide variety of deep-sea echinoderms from the northeast Atlantic has been examined. Time series samples of asteroids, ophiuroids, echinoids and holothurians are available from Station “M” and the Scottish Marine Biological Association's Permanent Station in the Rockall Trough and from opportunistic sampling in other areas of the northern Rockall Trough. Examination of these time series samples has established three main reproductive patterns in these taxa and one example of protandric hermaphroditism. The dominant reproductive pattern is the aperiodic production of relatively few large eggs usually in excess of 600μm diameter. Although the oogenic pattern is similar in most of these species, the follicle cell distribution and breakdown of relict oocytes vary considerably, particularly at family level. A second reproductive pattern is the production of numerous small eggs c. 100μm diameter, indicative of planktotrophic development. The five species exhibiting this pattern show intra- and interspecific synchrony of egg production with a proliferation of young oocytes in February to April of each year, vitellogenesis during summer and autumn and a synchronous spawnout in January–April of each year. In the apparent constant conditions of the deep sea, this synchrony of reproduction is related to the rapid descent of surface primary production. Two rarer reproductive patterns observed are the production of intermediate sized eggs (c. 300–400μm diameter) suggesting the formation of a lecithotrophic larva, and lastly a single case of protandric hermaphroditism, and the subsequent production of a large egg. In none of the species examined have we found any evidence of brooding. The variation in the reproductive pattern of individual species is discussed in relation to the constancy of the physico-chemical environment of the deep-sea.


2003 ◽  
pp. 1-7 ◽  
Author(s):  
Bruce Means

Living Amphibia exhibit two major life history modes, possession of an aquatic larval stage or direct development, with the latter assumed to be the derived evolutionary condition (Duellman and Trueb 1986, Wake 1989). A small group (n = 20 species) of plethodontid salamanders, the subfamily Desmognathinae, is of great interest because its members display both developmental modes (Marks 1995). For decades the prevailing phylogenetic hypothesis for the group, based upon morphology and habitat, was a monophyletic sequence from the larger, more aquatic species that possessed the longest larval lives to two dwarf terrestrial species with direct development Dunn (1926). This “aquatic to terrestrial” hypothesis remained unchallenged even with the discovery of a new, giant, fossorial species, the Alabama Red Hills Salamander (Phaeognathus hubrichti), that was thought to be a third species with direct development (Highton 1961).Recently, analysis of mtDNA sequences revealed that the terrestrial desmognathines form the three deepest branches in desmognathine phylogeny, compelling the authors to advance an alternative phylogenetic hypothesis that absence of an aquatic larval stage may be ancestral for desmognathines (Titus and Larsen 1996). Their hypothesis rested, however, on details of the developing embryo and hatchlings in the three species with direct development, but critical data on the eggs, hatchlings, and whether larvae exist in P. hubrichti are unavailable.Aspects of the reproductive biology of the rare and secretive Phaeognathus hubrichti are difficult to observe in the field because the species is a burrower. One clutch laid by a female kept in captivity for six years apparently was unfertilized because the eggs failed to develop (Brandon and Moruska 1982). The large size and small number of ripe ovarian oocytes observed in preserved specimens, coupled with the unusual terrestrial burrowing behavior of the species, suggest the absence of an aquatic larval stage (Brandon 1965).On several visits to one ravine in Butler Co., Alabama (31°32’N, 86°45’W) during the spring and summer of 2002, I repeatedly observed a 105 mm SVL gravid female, discovered her eggs, kept them in captivity until they hatched, then returned the female and her clutch alive back into the field. Here I describe the field observations, eggs, embryos, and hatchlings.


2006 ◽  
Vol 81 (1) ◽  
pp. 35-49 ◽  
Author(s):  
Brooke E. Flammang ◽  
David A. Ebert ◽  
Gregor M. Cailliet

Zootaxa ◽  
2019 ◽  
Vol 4550 (2) ◽  
pp. 185 ◽  
Author(s):  
FABRIZIO SCARABINO ◽  
RUDÁ AMORIM LUCENA ◽  
TOMÁS MUNILLA ◽  
ANNA SOLER-MEMBRIVES ◽  
LEONARDO ORTEGA ◽  
...  

Records of pycnogonids from Uruguayan waters (south-western Atlantic) include 26 species cited from precise locations, and at least five other species based on unconfirmed records. Nearly half of the species in that fauna belong to the genus Nymphon (12 spp.). Most species (22) come from deep-water and were recorded and described by C. A. Child. Of these, at least twelve species have an extended Antarctic and Subantarctic distribution, showing the influence of these cold waters in the area; three others have a wide deep-sea distribution pattern. Five species are known only from the lower slope and abyssal basin off La plata river: Mimipallene Atlantis and four species of Nymphon. Records from coastal and shelf areas (four species) are poorly documented and should be the focus of future research. Of these, Colossendeis geoffroyi is considered endemic in the Southwest Atlantic between 34ºS and 40ºS, but presents clear Antarctic affinities. A small-sized species living in shallow waters, Pycnogonum cessaci, is here considered as cryptogenic. 


2019 ◽  
Vol 85 (3) ◽  
pp. 287-299 ◽  
Author(s):  
Alexey V Golikov ◽  
Martin E Blicher ◽  
Lis L Jørgensen ◽  
Wojciech Walkusz ◽  
Denis V Zakharov ◽  
...  

Abstract The squid Gonatus fabricii (Lichtenstein, 1818) is the most abundant pelagic cephalopod in the Arctic and the only squid to spend all of its life cycle in this region. Despite being highly abundant, its reproductive biology remains poorly known, and data on large maturing and mature specimens are especially rare. This study, based on extensive material (51 large specimens and >35,000 specimens in all), fills major gaps in the knowledge of the reproductive biology and ecology of G. fabricii. The fecundity of females ranged from 8,862 to 16,200 oocytes, with mature and late maturing specimens having between 8,862 to c. 10,000 and 11,402 oocytes, respectively. Oogenesis was synchronous, and oocyte resorption was observed; resorbed oocytes constituted up to 23.5% of fecundity. Between two to five ripe oocytes were observed, and these were 4.0–5.5 mm in diameter (maximum dimension). Males possessed between 77 and 257 spermatophores (length = 5.8–10.8 mm). Spermatophores were characterized by a cement body with well-developed collar and discs at the oral end, an ejaculatory apparatus longer than the cement body and the lack of a tapered, sharp tip to the cement body. Spermatophore size showed a uniform increase in relation to increasing male size. In newer spermatophores, the length, width and volume of the seminal reservoir also increased. Females possessed between 62 and 84 spermatangia (length = 1.8–2.6 mm); the spermatangia were present on the buccal membranes and lacked special attachment structures. Seminal receptacles were not found on the buccal membranes of females. Our findings are consistent with the hypothesis of geographically restricted spawning in G. fabricii. The study found evidence for one new breeding area in south-eastern Greenland. No differences in sizes at maturity were found between the breeding areas. Such geographically localized reproduction is relatively common in non-deep-water squids, but is much less common in deep-water squids. Localized reproduction may be especially important for G. fabricii because increased food availability in the epipelagic layers would likely increase the survival of epipelagic juveniles, with surface currents potentially aiding in their dispersal.


2018 ◽  
Vol 19 (11) ◽  
pp. 4433-4443 ◽  
Author(s):  
Ji Young Shin ◽  
Yongjae Yu ◽  
Inah Seo ◽  
Kiseong Hyeong ◽  
Dhongil Lim ◽  
...  

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