A Moss Landing Marine Laboratories
thesis defense seminar by
Caren E. Braby
Friday, December 4, 1998
12:00 Noon—Pacific Forum
Cephalopods are fascinating organisms, known for their intelligence, their curiosity,
and their ability to form images on par with vertebrates. Mesopelagic
cephalopods—those living at a minimum of 200 meters depth during the
daytime—have enormous eyes, just like their shallow-living relatives. However,
cephalopods that live in the dark depths of the ocean may need other sensory systems to
compensate for the small amount of sensory input provided by light. To better understand
the chemosensory capabilities of coleoid cephalopod olfactory organs, this study used
electron microscopy comparative morphology and monitored behavioral responses to chemical
stimulation experiments.
Six species of mesopelagic cephalopods were included, all relatively common in Monterey
Bay, California: Histioteuthis heteropsis, Gonatus onyx, Chiroteuthis calyx,
Galiteuthis phyllura, Vampyroteuthis infernalis, and Japetella heathi. Animals
were captured by trawling (R/V Pt. Sur) or by ROV (R/V Pt. Lobos & ROV Ventana).
The length of the olfactory organ stalk is variable, ranging from being highly elongated
to being absent. The olfactory organ microstructure revealed a large morphological
diversity and unique ciliary and microvillar structures for each species, which suggests
both mechano- and chemoreception functions. Behavioral experiments targeted three known
loci of sensory epithelia: the arms/mouth region, the olfactory organs, and the sensory
filaments of V. infernalis. There were both mechano- and chemoreception responses.
The combination of morphological and behavioral data suggests that there are multiple
functions of the olfactory organs, including both mechano- and chemoreception. These
sensory pathways may be important complements to vision for ecological interaction in
mesopelagic cephalopods.
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35°N
Last updated: December 19, 2000
