title: Postural control under clinorotation in upside-down catfish, Synodontis nigriventris.
abstract: The upside-down catfish Synodontis nigriventris has a unique habit of swimming and resting upside-down in free water. This behavior leads to the assumption that the catfish has a specific gravity information processing system. We examined the postural control behaviors in the catfish under clinorotation which is usually used for producing pseudo-microgravity. Synodontis nigriventris kept its body posture at a stable area of the rotated flask in which the catfish was kept, when it was clinorotated at the rate of 60 rpm. In contrast to Synodontis nigriventris, a related species, Corydoras paleatus, did not show such steady postural control. When the flask was rotated at a lower rate of 30 rpm or a higher rate of 100 rpm, Synodontis nigriventris as well as Corydoras paleatus showed a considerable disturbed control of body posture. In this condition, they were frequently rotated with the flask. These findings suggest that Synodontis nigriventris has a high ability to keep upside-down posture and the gravity sensation in this catfish is likely to contribute to its different postural control from that of many other fishes.
authors.affiliation: Department of Physiology, Nara Medical University, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ohnishi
authors.forename: A
authors.initials: A
authors.lastname: Takahashi
authors.forename: M
authors.initials: M
authors.lastname: Koyama
authors.forename: T
authors.initials: T
authors.lastname: Ohnishi
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D002397:Catfishes / Q000502:physiology*; D005403:Fixation, Ocular / Q000502:physiology; D006112:Gravitation; D018466:Gravity Sensing / Q000502:physiology*; D009043:Motor Activity / Q000502:physiology*; D009949:Orientation / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D012399:Rotation / Q000009:adverse effects*; D013550:Swimming; D018474:Weightlessness Simulation