About the Cover
Cover
“Biology of Marine Invertebrate Larvae,” the “virtual symposium” in this issue, offers a glimpse of the broad extent of current research on early life stages of marine invertebrates. The images on the cover are a small sample of some of the early developmental stages and larvae that are considered in research, review, and position papers presented in this issue. All stages are about 1 millimeter, or less, in size. Clockwise from top: the large and yolky egg of the sea star Nepanthia troughtoni; a zoea larva of a crab in the family Cancridae; a feeding, late-stage pluteus larva of the sea urchin Tripneustes gratilla; a nonfeeding brachiolaria larva of a sea star collected with a plankton net; a feeding veliger larva of a gastropod in the Thaidae, a family of carnivorous snails; and a nonfeeding, coronate larva of a colonial “moss animal” in the bryozoan genus Bugula. The central image is a confocal z-projection of a phallacidin-labeled planktonic planuliform larva of the nemertean worm Paranemertes peregrina.
Larvae occur between the embryonic and juvenile stages of most marine invertebrates. They are small (on the order of 1 mm), slow moving, and usually found suspended in the water where they are dispersed by currents. As individuals they exhibit behavior: they swim, (often) feed, respond to many environmental stimuli, and eventually settle and metamorphose to become juveniles. Larvae are studied for many reasons, including their unusual anatomy and behavior (compared to that of adults), their dynamic development as they change from embryos to juveniles, their dispersal which links populations genetically, and their recruitment as they contribute new individuals to local populations and influence population dynamics. Larval forms and variations among them have also been foci in considerations of animal evolution and animal ecology, and more recently, of how developmental mechanisms and evolutionary forces interact to create the diversity of organisms found among invertebrate phyla.
Photo credits: Confocal image of the planuliform larva of Paranemertes peregrina, Svetlana Maslakova (University of Oregon). All other cover images, Richard Emlet (University of Oregon). Cover design: Beth Liles (Marine Biological Laboratory).
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Copyright © 2009 by the Marine Biological Laboratory.
