scholarly journals Fertilization Success in Marine Invertebrates: The Influence of Gamete Age

2002 ◽  
Vol 202 (1) ◽  
pp. 34-42 ◽  
Author(s):  
Mark Elliott Williams ◽  
Matthew Graeme Bentley
2000 ◽  
Vol 51 (1) ◽  
pp. 55 ◽  
Author(s):  
Russ Babcock ◽  
Elke Franke ◽  
Neill Barr

Measurements of fertilization rates in free-spawning marine invertebrates have shown that reproductive success is related to both behavioural and environmental factors. Water depth has been suggested as being one such factor affecting fertilization success. In experimental spawnings of the sea star Coscinasterias muricata, fertilization rates decreased exponentially with distance from sperm source but were frequently greater than 20% at distances >10 m downstream. Current speed did not have a significant effect on fertilization rate over the range of velocities examined. Fertilization rates directly downstream from spawning individuals were higher in shallow water (<1 m) than in deep water (>5 m). Diffusion models using empirically derived site-dependent diffusion parameters supported these findings but suggested that this would only be true for eggs released directly downstream from a sperm source. Once lateral diffusion of sperm was accounted for, the model predicted little overall difference in fertilization rates for shallow and deep spawners. These results from Coscinasterias indicate that movements into shallow water at the time of spawning, which have been reported in several asteroid species, may provide little reproductive advantage in environments experiencing net flow conditions.


2001 ◽  
Vol 138 (6) ◽  
pp. 1153-1161 ◽  
Author(s):  
Not Available Not Available ◽  
Not Available Not Available ◽  
Not Available Not Available

Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.


Planta Medica ◽  
2013 ◽  
Vol 79 (10) ◽  
Author(s):  
DTA Youssef ◽  
LA Shaala ◽  
F Al-Jamali ◽  
E Schmidt

2014 ◽  
Vol 41 (1) ◽  
pp. 1-16 ◽  
Author(s):  
B. J. Gill

In December 1884 Charles Francis Adams (1857–1893) left Illinois, USA, by train for San Francisco and crossed the Pacific by ship to work as taxidermist at Auckland Museum, New Zealand, until February 1887. He then went to Borneo via several New Zealand ports, Melbourne and Batavia (Jakarta). This paper concerns a diary by Adams that gives a daily account of his trip to Auckland and the first six months of his employment (from January to July 1885). In this period Adams set up a workshop and diligently prepared specimens (at least 124 birds, fish, reptiles and marine invertebrates). The diary continues with three reports of trips Adams made from Auckland to Cuvier Island (November 1886), Karewa Island (December 1886) and White Island (date not stated), which are important early descriptive accounts of these small offshore islands. Events after leaving Auckland are covered discontinuously and the diary ends with part of the ship's passage through the Dutch East Indies (Indonesia), apparently in April 1887. Adams's diary is important in giving a detailed account of a taxidermist's working life, and in helping to document the early years of Auckland Museum's occupation of the Princes Street building.


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