Research Training Program

Smithsonian Institution
National Museum of Natural History

PROJECT SUMMARY
1997

Sea McKeon
The Evergreen State College
Olympia, Washington
Michael Vecchione, Ph.D.
Clyde Roper, Ph.D.
Supervising Scientists
Department of Invertebrate Zoology
"This summer was a learning experience I shall never forget "

Paralarval Clues to Onychoteuthid Questions

ABSTRACT
Paralarvae, the planktonic life stage of cephalopods, are differentiated from other life stages by both ecological and morphological differences. Our understanding of adult cephalopods is limited, but our comprehension of their young is all but non-existent. In recent years as scientists have looked more and more deeply into the working of the world's oceans, paralarval morphology has proven to be a useful tool in gaining a greater understanding of these enigmatic creatures.

This research project focused on the family Onychoteuthidae, a cosmopolitan group of oegopsid (oceanic) squids, in the Mid-North Atlantic part of their range. Specimens were from the Amsterdam Mid-North Atlantic Plankton Expedition conducted during 1980-83. The majority of specimens examined belong to the Onychoteuthis banksi-complex, but despite distinct "morphotypes" based on photophore patterns, individuals of this complex could not be divided into species on these grounds. The remaining samples divided into three groups: Ancistroteuthis, Onykia, and a mysterious group here thought to represent at least two species of Moroteuthis. Ancistroteuthis was distinguished from Onychoteuthis at a mantle length of 6mm and greater, on the basis of funnel and retractor muscle characters. While the issue was not explored fully due to small sample size, the relationship of Onykia and Moroteuthis were examined via their paralarvae, giving rise to questions regarding paedomorphosis and the ecologically based definition of the paralarval stage. This research has given rise to new questions to pursue in the the field of Evolutionary Ecology, and furthered a desire to find creative ways of studying the complex life cycles of pelagic species.

This research was supported by a grant from the National Science Foundation Research Experiences for Undergraduates program, Award Number DBI-9531331.

Letter of Gratitude