CSIRO Publishing blank image blank image blank image blank imageBooksblank image blank image blank image blank imageJournalsblank image blank image blank image blank imageAbout Usblank image blank image blank image blank imageShopping Cartblank image blank image blank image You are here: Journals > Australian Journal of Zoology   
Australian Journal of Zoology
Journal Banner
  Evolutionary, Molecular and Comparative Zoology
blank image Search
blank image blank image
blank image
  Advanced Search

Journal Home
About the Journal
Editorial Structure
Online Early
Current Issue
Just Accepted
All Issues
Special Issues
Sample Issue
For Authors
General Information
Author Instructions
Submit Article
Open Access
Awards and Prizes
For Referees
Referee Guidelines
Review an Article
Annual Referee Index
For Subscribers
Subscription Prices
Customer Service
Print Publication Dates

blue arrow e-Alerts
blank image
Subscribe to our Email Alert or RSS feeds for the latest journal papers.

red arrow Connect with us
blank image
facebook twitter LinkedIn


Article << Previous     |     Next >>   Contents Vol 23(3)

The reproductive system, embryonic development, larval development and metamorphosis of the sea urchin Heliocidaris erythrogramma (Val.) (Echinoidea : Echinometridae)

DHC Williams and DT Anderson

Australian Journal of Zoology 23(3) 371 - 403
Published: 1975


H. erythrogramma has an annual reproductive cycle, spawning asynchronously. The female cycle has five phases: resting, regenerating, mature, spent and regressing; the male cycle omits the regression phase. Regression and resting occur only during April-August; regeneration begins in September; during December-March individual urchins pass through the mature, spent and regenerating phases two or three times. The egg averages 400 ¼m diameter and floats at the water surface. At 24-25ºC, equal, total, radial cleavage yields a wrinkled coeloblastula by 6-7 hours; this undergoes egression, becoming a spherical stereoblastula by 13-14 hours; during this process an acellular central yolk mass is segregated from a peripheral columnar blastoderm. The ciliated stereoblastula gastrulates by a typical diphasic invagination, beginning at 15 hours, and the gastrulating embryo hatches as a ciliated, planktonic yolk-larva at 15-16 hours. Lecithotrophic development of the yolk-larva to a uniformly ciliated, planktonic vitellaria is complete by 1.5 days, and the larva metamorphoses gradually to a lecithotrophic juvenile over the next 3.5 days. It remains planktonic during the first half of this period (to 3.75 days), but settles during the second half (to 5 days). The juvenile begins to feed >3 weeks after settling. Vegetally proliferating mesenchyme invades the yolk mass during gastrulation. Invagination of the archenteron is followed by evagination of a primary pair of coelomic pouches from its wall; the left enterocoel forms the hydrocoel. Other coelomic cavities are re-formed by schizocoely. The larval gut rudiment temporarily loses connection with the exterior after the blastopore closes. The proctodaeum and stomodaeum of the juvenile form secondarily during and after metamorphosis. Ectodermal development of the echinus rudiment, though gradual, is typical of echinoids. The blastulation of H. evythrogramma is unique among large-egged echinoderms in combining egression of a wrinkled coeloblastula with segregation of a blastoderm around a central yolk mass. The development of the species supports the view that the vitellaria larva is secondarily evolved within the Echinoidea.

Full text doi:10.1071/ZO9750371

© CSIRO 1975

blank image
Subscriber Login

PDF (2.2 MB) $25
 Export Citation
Legal & Privacy | Contact Us | Help


© CSIRO 1996-2015