Advances in MARINE BIOLOGY VOLUME 9 This Page Intentionally Left Blank Advances in MARINE BIOLOGY VOLUME 9 Edited by SIR FREDERICK S. RUSSELL Plymouth, England and SIR MAURICE YONGE Edinburgh, Scotland Academic Press London and New York 1971 ACADEMIC PRESS INC. (LONDON) LTD. BERKELEY SQUARE HOUSE BERKELEY SQUARE LONDON, W l X 6BA U.S. Edition published by ACADEMIC PRESS INC. 111 FIFTH AVENUE NEW YORK, NEW YORK 10003 Copyright 0 1971 by Academic Press Inc. (London)Ltd., All rights reserved N O PART OF THIS BOOK MAY BE REPRODUCED IN ANY FORM BY PHOTOSTAT, MICROFILM, OR ANY OTHER MEANS, WITHOUT WRITTEN PERMISSION FROM THE PUBLISHERS Library of Congress Catalog Card Number: 63-14040 ISBN: 0-1 2-026109-X PRINTED IN QREAT BRITAIN B Y THE WHITEFRIARS PRESS LTD. LONDON AND TONBRIDQE CONTRIBUTORS TO VOLUME 9 J. A. ALLEN, Dove Marine Laboratory, University of Newcastle upon Tyne, Cullerwats, North Shields, Northumberland, England. N. BALAKRISHNAN N u , The Marine Biological Laboratory, University of Kerala, Trivandrum-7, Kerala, India. E. D. S. CORNER,Marine Biological Association of the United Kingdom, The Laboratory, Citadel Hill, Plymouth, Devon, England. D. H. CUSHING), Fisheries Laboratory, Lowestoft, Suffolk, England. ANTHONYG. DAVIES,Marine Biological Association of the United Kingdom, The Laboratory, Citadel Hill, Plymouth, Devon, England. M. R. GARRETT,Dove Marine Laboratory, University of Newcastle upon, Tyne, Cullercoats, North Shields, Northumberland, England. R. H. MILLAR,Scottish Marine Biological Association, Dunstaffnage Marine Research Laboratory, Oban, Argyll, Scotland. M. SARASWAT~EY, Indian Ocean Biological Centre, N a t i o d Institute of Oceanogrqhy, Cochin, India. This Page Intentionally Left Blank CONTENTS CONTRIBUTORSTO VOLUME 9 .. .. .. .. .. v .. .. *. 1 .. .. .. .. .. .. The Biology of Ascidians R.H. MILLm I. Introduction .. .. .. .. .. 11. Feeding A. The Feeding Mechanism B. Food.. .. .. .. .. .. .. HI. Breeding .. A. Breeding Season B. Spawning .. C. The Larva . . a . .. .. .. .. .. .. .. .. .. .. *. .. .. .. .. *. .. .. .. .. .. .. *. IV. Life Cycle: Growth, Succession of Generations and .. Mortality .. .. .. .. 0 . .. .. . .. V. Ecology . .. A. The Numbers and Biomass of Ascidians . . *. 2 2 4 6 6 13 14 22 B. Changes in Populations .. C. Factors Affecting Distribution and Abundance. . 33 33 35 36 .. .. 47 48 .. 8 . .. .. VI. Predators, Parasites, Commensals and Symbionts .. .. A. Predators .. .. B. Commensals, Parasites and Symbionts VII. Geographical Distribution A. Shallow-W