Locomotion modes of deep-sea cirrate octopods (Cephalopoda) based on observations from video recordings on the Mid-Atlantic Ridge |
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Authors: | R Villanueva M Segonzac A Guerra |
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Institution: | (1) Institut de Ciències del Mar (CSIC), Paseo Juan de Borbón s/n, E-08039 Barcelona, Spain, ES;(2) IFREMER/CENTOB, BP 70, F-29280 Plouzane Cedex, France, FR;(3) Instituto de Investigaciones Marinas (CSIC), Eduardo Cabello 6, E-36208 Vigo, Spain, ES |
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Abstract: | The behaviour of cirrate octopods of the genera Cirroteuthis and Grimpoteuthis in their natural habitat was studied using video recordings. Sequences were filmed during the French cruise “Faranaut”, from
the manned submersible “Nautile” at depths between 2702 and 4527 m, in two zones in the Fifteen-Twenty Fracture Zone on the
Mid-Atlantic Ridge. Four different modes of active locomotion, namely crawling, take-off, fin-swimming, and pumping, and one
apparently passive mode of locomotion, umbrella-style drifting, were observed. Jet-propulsion, a characteristic mode of locomotion
typically employed by cephalopods, was not observed in the cirrate octopods filmed, although breathing movements of the mantle
to aerate the gills were assumed to generate some slight propulsion through the funnel. Fin-swimming was the mode of active
locomotion most frequently observed. Neutral buoyancy was confirmed in one individual after capture. This buoyancy enables
passive drifting in the umbrella-style attitude observed in Cirroteuthis spp., possibly using near-bottom ocean currents. Pumping, a mode of slow locomotion generated by peristaltic waves in the
primary and intermediate webs, also observed in Cirroteuthis sp., is described here for the first time. The take-off mode of locomotion, a sudden, single contraction of the brachial
crown and web, is also described; it was always followed by fin-swimming. No medusoid swimming of the type previously described
for opisthoteuthid cirrates was observed. A flight response to the approach of or contact with a strange object, i.e. the
submersible, using the crawling, take-off, or fin-swimming modes was observed. A ballooning response was observed in a high-stress
situation when a C.magna individual was captured.
Received: 27 November 1996 / Accepted: 9 December 1996 |
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