Terrestrial locomotion in the climbing perch, Anabas testudineus (Bloch) (Anabantidea, Pisces)

Abstract

Climbing perches use the tail for forward propulsion when on land. The spiny gill covers are used to obtain purchase on the substratum. Unusually amongst teleosts, the opercular and subopercular bone are not bound strongly together into a single operculum. Instead they are joined only by a thin, flexible membrane, so that the fish has two sections of the gill cover hinged separately; the opercular on the suspensorium and the subopercular on the rearmost part of the lower jaw. The gill covers open very widely and the subopercular rotates ventrally as well as laterally. Two modes of locomotion are employed. Usually Anabus adopts a near‐upright posture and alternately drives the left and right spiny suboperculars into the substratum, using the tail to vault over the subopercular (which acts in the manner of a short vaulting pole). During vigorous movement the fish may leave the substratum altogether during the vault. Fatigued fish, or fish which have fallen during climbing, move on their sides, using the tail for propulsion and a single spiny opercular which is repeatedly driven into the substratum. Maximum speeds observed on land corresponded to 1.8 body lengths S−1. No evidence of involvement of the pelvic fins in locomotion was obtained; the pectorals seemed only to help in tilting the head from side to side and did not contribute significantly to forward propulsion. On mud and tree bark the fish were laterally unstable, often resting on their sides. Grassy substrata provided support and permitted a more upright posture. Slope climbing ability was restricted to 25° when climbing tree bark and 30° when climbing grass. Coupled with lateral instability these observations disqualify the species from any tree‐climbing capacity. Anabas can climb vertical obstacles of at least half body length in height by pushing the head against the obstacle, using the spiny gill covers for purchase until one or other subopercular hooks over the top of the barrier. The subopercular is then used as a fulcrum for an upwards vault to clear the obstacle.

Both seawater acclimation and environmental ammonia exposure lead to increases in mRNA expression and protein abundance of Na+:K+:2Cl− cotransporter in the gills of the climbing perch, Anabas testudineus

“…During drought, A. testudineus stays in pools associated with submerged woods and shrubs (Sokheng et al 1999) or buries under the mud (Rahman 1989). Furthermore, it can travel long distances on land between pools of water, covering several hundred meters per trip when the air is suYciently humid (Davenport and Abdul Martin 1990). Its air-breathing capacity and ability to survive on land have attracted a lot of attention in the past, but its ability to inhabit a brackish environment has been largely neglected until recently.…”

Cystic fibrosis transmembrane conductance regulator in the gills of the climbing perch, Anabas testudineus, is involved in both hypoosmotic regulation during seawater acclimation and active ammonia excretion during ammonia exposure

“…During drought, A. testudineus stays in pools associated with submerged woods and shrubs (Sokheng et al 1999) or buries under the mud (Rahman 1989). Furthermore, it can travel long distances on land between pools of water, covering several hundred meters per trip when the air is sufficiently humid (Davenport and Abdul Martin 1990). Its air-breathing capacity and ability to survive on land have attracted a lot of attention in the past, but its ability to inhabit a brackish environment has been neglected until recently.…”

Effect of Chlorpyrifos Ethyl on Acetylcholinesterase Activity in Climbing Perch (Anabas testudineus, Bloch, 1972)

“…The ability to use oxygen directly from the atmosphere makes climbing perch less sensitive to low oxygen levels in water, and the low levels of DO during the experiments were not seen to affect the survival of the fish (Armbruster 1998). Many studies have shown that climbing perch can tolerate and adapt to extremely harsh environments such as low pH values, high temperatures, and especially low DO concentrations (Davenport and Abdulmatin 1990;Khoa and Huong 1993;Klepper et al 1992).…”