Factors influencing the water speed of swimming sea hares, Aplysia brasiliana

• Published in: Animal behaviour Vol. 32; no. 2; pp. 367 - 373
• Main Author: Hamilton, P.V.
• Format: Journal Article
• Language: English
• Published: Kent Elsevier Ltd 01.01.1984; Elsevier
• Subjects: Animal ethology; Aplysia brasiliana; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Marine; Protozoa. Invertebrata; Psychology. Psychoanalysis. Psychiatry; Marine environment; Locomotion; Swimming; Behavior; Gastropoda; Invertebrata; Mollusca
• ISSN: 0003-3472; 1095-8282
• DOI: 10.1016/S0003-3472(84)80270-5

Swimming data for Aplysia brasiliana, a gastropod mollusc, were studied to determine what variables influence water speed (i.e. the velocity of travel relative to the water mass). Water speeds varied from 2.5 to 14 m/min. Water speed was primarily correlated with current aspect (i.e. the angular difference between the animal's heading and the current direction), and the relationship was strongest at high current speeds. This relationship is termed the Thrust Modulation Response (TMR). High waves caused significant underestimation of water speed, and high waves also detracted from TMR clarity for other reasons. Water speed was not significantly correlated with release number, current speed, current component, wave component, water depth or sun aspect. Although considerable variance in water speed was not accounted for by the variables studied, it is clear that future field experiments on mechanisms underlying the TMR should be done when current speeds are high and wave heights are low.