Showing papers on "Holothuria published in 2001"

Influence of asexual reproduction on the structure and dynamics of Holothuria (Halodeima) atra and Stichopus chloronotus populations of the Great Barrier Reef

Abstract: To determine the effect of asexual reproduction by transverse fission on the population structure of holothurians, ensities and individual weights of Holothuria atra (JAAger,1833)and Stichopus chloronotus (Brandt, 1835)were measured over a 26-month period on near-shore reefs of the Great Barrier Reef. Densities of H.atra (0.01—0.69 individuals m –2 )and S. chloronotus (0.11—1.67) did not increase during periods of intense asexual reproduction, and the density on each reef remained relatively stable.The effect of fission was clearly visible in the weight —frequency distributions of both species. The average individual wet weight in each population declined (H. atra from 105/134 g to 64/94 g in two respective populations;S. chloronotus from 128/302 g to 82/190 g in two respective populations) with the onset of fission in early winter, and more individuals in the weight range of fission products were found. The biomass followed the seasonal trend of the average weights for both species, with minimum values in winter. A conceptual model based on these and previous findings identified five possible factors (mortality, habitat stability, optimum individual size, food availability, larval supply) involved in promoting or repressing transverse fission, and the model indicated the consequences for the population.

Ossicle change in Holothuria scabra with a discussion of ossicle evolution within the Holothuriidae (Echinodermata)

Abstract: Ossicles of Holothuria (Metriatyla) scabra Jaeger 1833 vary mainly in early juveniles between 0.9 and 15mm long. While ossicles were not observed in auricularia and doliolaria larvae, which instead possessed elastic balls, ossicles were present in late pentactulae. Specimens 0.9–1.5mm long have tables with tall spire (4–5 cross beams), no buttons, and large irregular perforated plates. Specimens 5–6mm long have tables with moderate spire (2–4 cross beams) and a few smooth buttons. Specimens 9–16mm long have tables with low spire (1–2 cross beams) and knobbed buttons. From 30mm, ossicle are similar to those of adults, with more buttons and fewer tables. Several features of the ossicles of early juveniles, including their size, shape and prevalence, are unique to the species. Comparison with holothurian juveniles of other species indicates that presence of tables with tall spire and absence of buttons are plesiomorph characters in the evolution of the Holothuriidae.

Spawning and larval rearing of the sea cucumber Holothuria(Theelothuria) spinifera Theel at Tuticorin

Abstract: In India, the Beche-demer-industry is mainly depending on Holothuria scabra (vella attai). A hatchery technology for the species has already been developed in 1988. In addition to this, another species Holothuria spintfera (chenna attai, or raja attai) is also being fished in large quantities and widely processed along the coast of Gulf of Mannar and Palk Bay.