Meeting Abstract

AMS.1  Wednesday, Jan. 5  The discovery and naming of marine larval forms: shallow and deep, then and now YOUNG, Craig M.; Oregon Institute of Marine Biology, University of Oregon

The description of life cycles and the discovery of larval forms were mainstream endeavors in the 18th and 19th centuries and these activities captured the attention of amateur microscopists such as Marinus Slabber and John Vaughn Thompson, of at least one medical student, Charles Darwin, and of some of the most prominent professional biologists of their day. The latter luminaries included Scottish Renaissance man Sir John Graham Dalyell, Germany’s foremost human physiologist, Johannes Muller, and the Russian embryologists Alexander Kowalevsky and Nobel prize winner Elie Metchnikoff, the father of immunology. Each life-cycle biologist had an interesting life story of his own, instructive when viewed in the context of the times and amazing when considered in light of the microscopes available to them. In the 20th and 21st centuries, few additional larval forms have been discovered, mostly among parasites and meiofauna. Recent discoveries in the deep sea have yielded some surprises, including the megalarva of loriciferans and Waren’s larva, a previously unknown life-history stage in a hydrothermal vent caenogastropod. The discovery of trochophore larvae in vestimentiferan siboglinid polychaetes at methane seeps and hydrothermal vents helped clarify the phylogenetic position of this group at a time when the closest relatives were thought by many to be deuterostomes. More recently, larval work with whale-bone-eating worms revealed dwarf males that appear to be neotonous larvae, and the rearing of bathyal echinoderm larvae to metamorphosis reveals surprisingly long larval lives in the deep sea.