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T.W. Cranford
6.4 Anatomic Asymmetry
Questions surrounding the asymmetry in the heads of odontocetes are
fascinating. It is interesting to note that odontocete cranial and/or cephalic
soft-tissue asymmetry have long been recognized, and often referred to or
speculated upon, but have rarely been quantified or examined in detail
(Norris 1964; Mead 1975; Heyning 1989). What is peculiar about odontocete cephalic asymmetry is that it is directional and can be large in magnitude (Cranford 1992a, b). Directional asymmetry is uncommon zoologically
but when it occurs it is always associated with functional specialization or
a specific adaptation and rarely is it large in magnitude. This is in contrast
to fluctuating asymmetry (which is common) or antisymmetry (which is a
quantum phenomenon, as in left- or right-sided halibut). In the case of
odontocetes, we may find more than One specialization or selective pressure driving asymmetry in different directions for different structures in the
head (Cranford, Amundin Norris 1996). The most intriguing aspects of the
questions and answers regarding directional asymmetry in odontocetes
are not the ramifications for biosonar but the implications for ecology and
evolution.
6.5 Experiments with Free-Swimming Animals
Most behaviors are a complex symphony of physiological events
coupled to interdependent external stimuli. From what little we know
about biosonar behavior in untethered or unrestricted animals, it often
becomes a brief rapid-fire physiologic interaction between predator
and prey. Probing and comprehensive studies of these naturally occurring
behaviors are in an advanced state for bats but are in their infancy for
odontocetes.
Undoubtedly, One of the most intriguing and promising horizons in odontocete biosonar research is one that allows us to study the behavior in freeswimming animals (c.t. Sigurdson 1997a; Verfuss et al. 1999). The glimpses
we gain into the physiological ecology of odontocetes with this kind of
research could catalyze a significant shift in the paradigm through which we
currently view their lives.
7. Conclusion
Clearly there are several unsolved puzzles yet to be explored in the arena
of odontocete biosonar signal generation and beam formation. The solutions to these puzzles will have implications for our understanding of
odontocete evolution, phylogeny, feeding ecology, social structure, and
physiological ecology. Two· guiding principles that should keep us on the
T.W. Cranford
6.4 Anatomic Asymmetry
Questions surrounding the asymmetry in the heads of odontocetes are
fascinating. It is interesting to note that odontocete cranial and/or cephalic
soft-tissue asymmetry have long been recognized, and often referred to or
speculated upon, but have rarely been quantified or examined in detail
(Norris 1964; Mead 1975; Heyning 1989). What is peculiar about odontocete cephalic asymmetry is that it is directional and can be large in magnitude (Cranford 1992a, b). Directional asymmetry is uncommon zoologically
but when it occurs it is always associated with functional specialization or
a specific adaptation and rarely is it large in magnitude. This is in contrast
to fluctuating asymmetry (which is common) or antisymmetry (which is a
quantum phenomenon, as in left- or right-sided halibut). In the case of
odontocetes, we may find more than One specialization or selective pressure driving asymmetry in different directions for different structures in the
head (Cranford, Amundin Norris 1996). The most intriguing aspects of the
questions and answers regarding directional asymmetry in odontocetes
are not the ramifications for biosonar but the implications for ecology and
evolution.
6.5 Experiments with Free-Swimming Animals
Most behaviors are a complex symphony of physiological events
coupled to interdependent external stimuli. From what little we know
about biosonar behavior in untethered or unrestricted animals, it often
becomes a brief rapid-fire physiologic interaction between predator
and prey. Probing and comprehensive studies of these naturally occurring
behaviors are in an advanced state for bats but are in their infancy for
odontocetes.
Undoubtedly, One of the most intriguing and promising horizons in odontocete biosonar research is one that allows us to study the behavior in freeswimming animals (c.t. Sigurdson 1997a; Verfuss et al. 1999). The glimpses
we gain into the physiological ecology of odontocetes with this kind of
research could catalyze a significant shift in the paradigm through which we
currently view their lives.
7. Conclusion
Clearly there are several unsolved puzzles yet to be explored in the arena
of odontocete biosonar signal generation and beam formation. The solutions to these puzzles will have implications for our understanding of
odontocete evolution, phylogeny, feeding ecology, social structure, and
physiological ecology. Two· guiding principles that should keep us on the