Heads or tails: do stranded fish (mosquitofish, Gambusia affinis) know where they are on a slope and how to return to the water?

Boumis, Robert J. and Ferry, Lara A. and Pace, Cinnamon M. and Gibb, Alice C. (2014) Heads or tails: do stranded fish (mosquitofish, Gambusia affinis) know where they are on a slope and how to return to the water? PLoS ONE, 9 (8). e104569. ISSN 1932-6203

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Abstract

Aquatic vertebrates that emerge onto land to spawn, feed, or evade aquatic predators must return to the water to avoid dehydration or asphyxiation. How do such aquatic organisms determine their location on land? Do particular behaviors facilitate a safe return to the aquatic realm? In this study, we asked: will fully-aquatic mosquitofish (Gambusia affinis) stranded on a slope modulate locomotor behavior according to body position to facilitate movement back into the water? To address this question, mosquitofish (n = 53) were placed in four positions relative to an artificial slope (30° inclination) and their responses to stranding were recorded, categorized, and quantified. We found that mosquitofish may remain immobile for up to three minutes after being stranded and then initiate either a “roll” or a “leap”. During a roll, mass is destabilized to trigger a downslope tumble; during a leap, the fish jumps up, above the substrate. When mosquitofish are oriented with the long axis of the body at 90° to the slope, they almost always (97%) initiate a roll. A roll is an energetically inexpensive way to move back into the water from a cross-slope body orientation because potential energy is converted back into kinetic energy. When placed with their heads toward the apex of the slope, most mosquitofish (>50%) produce a tail-flip jump to leap into ballistic flight. Because a tail-flip generates a caudually-oriented flight trajectory, this locomotor movement will effectively propel a fish downhill when the head is oriented up-slope. However, because the mass of the body is elevated against gravity, leaps require more mechanical work than rolls. We suggest that mosquitofish use the otolith-vestibular system to sense body position and generate a behavior that is “matched” to their orientation on a slope, thereby increasing the probability of a safe return to the water, relative to the energy expended.

Item Type:	Article
Publisher’s Statement:	Published by: Public Library of Science. Creative Commons Attribution License.
ID number or DOI:	10.1371/journal.pone.0104569
Keywords:	Actinopterygii; Animal behavior; Animal evolution; Animal physiology; Animals; Asphyxia; Biological locomotion; Biology and life sciences; Biomechanics; Ecology; Evolutionary Biology; Evolutionary ecology; Evolutionary physiology; Evolution (Biology); Fish biology; Fishes; Organismal evolution; Organisms; Osteichthyes; Physiology; Predatory aquatic animals; Research Article; Responses; Sensory physiology; Vertebrates; Western mosquitofish; Zoology
Subjects:	Q Science > QL Zoology
NAU Depositing Author Academic Status:	Faculty/Staff
Department/Unit:	College of Engineering, Forestry, and Natural Science > Biological Sciences
Date Deposited:	12 Oct 2015 23:09
URI:	http://openknowledge.nau.edu/id/eprint/1397

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