Reproductive biology of the deep-sea holothurians Laetmogone violacea and Benthogone rosea (Elasipoda: Holothurioidea)

Abstract

Specimens were examined from a number of stations (960 to 2120 m depth) in the Porcupine Seabight and Rockall Trough, N. E. Atlantic Ocean. Both species are gonochoric and show an equal division of the sexes. The ovary of Laetrnogone violacea is a compact nodose structure containing eggs up to 400 pm diameter. The testis is highly digitate, with the wall of each tubule containing numerous infoldings lined with spermatogonia and spermatocytes; spermatozoa reach a maximum size of 2 pm (head diameter). The ovary of Benthogone rosea consists of thin-walled nodose tubules through which the large egg of 750 pm diameter can be clearly seen. The testis of B. rosea is a small digitate structure, the walls of which lack the infoldings found in L. v~olacea; spermatozoa have a head diameter of 5 to 7 pm. In neither species is there any evidence for reproductive seasonality.

Temporal variations in fatty acid composition of deep-sea holothurians: evidence of bentho-pelagic coupling

“…A. rosea has a maximum egg diameter of 200 µm (Wigham et al 2003a), B. natans 280 µm (Tyler et al 1994) and L. violacea 400 µm (Tyler et al 1985) (Table 5). It seems probable that all these species accumulate and store PUFAs at times when fresh phytodetritus is available.…”

“…Eggs are developed, depleting PUFAs, so that juveniles developed directly from the egg enter the environment when food resources are high. Tyler et al (1985, Tyler & Billett (1987) and suggested that there is no evidence of seasonal changes in fecundity in these species, but egg numbers are low, so it may be difficult to determine.…”

“…Bathyal holothurians such as Laetmogone violacea, Paroriza pallens and Bathyplotes natans are common in the Porcupine Seabight (Billett 1991). Paradoxically, less is known, perhaps, about the biology of these bathyal holothurians than their abyssal relatives in the NE Atlantic, although the reproductive biology of several species has been described (Tyler et al 1985(Tyler et al , 1994. The benthic community in the Porcupine Abyssal Plain is dominated by over 10 species of deposit-feeding holothurians ranging from the infaunal Molpadia blakei to the benthopelagic Peniagone diaphana (Billett et al 2001).…”

Aspects of the ecology ofStichopus mollis(Echinodermata: Holothuroidea) in north‐eastern New Zealand

“…Because measurements of total weight can vary owing to differing amounts of sediment in the gut (Choe 1963;Tyler et al 1985b), after collection the sea cucumbers were maintained in individual bags (5 mm plastic mesh), suspended from a metal frame in a 500-litre pool of running sea water for 24 h, to permit emptying of sediment from the alimentary canal. They were transferred to a 15-litre aquarium before dissection to achieve a natural body form after contraction in the holding bags.…”

On the reproduction of the simultaneous hermaphrodite Paroriza prouhoi (Holothuroidea: Synallactidae) in the Porcupine Abyssal Plain, north-east Atlantic

“…The pattern of asynchronous oocyte development in P. prouhoi resembles reproductive patterns that have been recorded for dioecious holothurians from bathyal (Tyler et al, 1985bBillett, 1991) and abyssal depths (Tyler & Gage, 1983;Tyler et al, 1985aWigham et al, 2003b;Ramirez-Llodra et al, 2005) in the north-east Atlantic. Only a small number of species, mainly echinoderms, have been shown to have seasonal patterns of gametogenesis Tyler, 1988;Gooday, 2002;Gage et al, 2004).…”