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Biological Factors


For marine creatures the most important way to distribute offspring to suitable new sites is by casting their fertilised eggs or juveniles adrift as plankton into water currents. Most intertidal female animals produce hundreds, if not thousands, of eggs. Most will not survive into adulthood, but are an excellent food supply for some other kind of animal.

A planktonic development pattern is common in most cnidaria, echinoderms, molluscs, barnacles, decapod crabs and ascidians.

The important issue is whether the currents will return the plankton to a suitable site for juveniles to settle and grow to become reproductively mature adults.


Bennett, I. (1987) W. J. Dakin's classic study: Australian Seashores. Angus & Robertson, Sydney.

Davey, K. (1998) A Photographic Guide to Seashore Life of Australia. New Holland, Sydney.

Underwood, A. J. & Chapman, M. G. (1993) Seashores: a beachcomber's guide. New South Wales University Press, Sydney.


Biological Factors
Oxygen & Respiration
Food and Predation

Home Page
Rocky Shores
Tidal Levels
Intertidal Zonation
Environmental Factors
Biological Factors
Feeding Relationships


photo of Keith DaveyLife on Australian Seashores
by Keith Davey (C) 2000

Learning Consultant - Media
The University of Newcastle

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Scientific Consultant: Phil Colman
site created 01.01.98 : updated 01.04.2000