Butler Julie M, Whitlow Sarah M, Gwan Anwei P, Chakrabarty Prosanta, Maruska Karen P
Department of Biological Sciences, Louisiana State University, 202 Life Sciences Building, Baton Rouge, LA 70803, USA
Department of Biological Sciences, Louisiana State University, 202 Life Sciences Building, Baton Rouge, LA 70803, USA.
J Exp Biol. 2017 Dec 1;220(Pt 23):4463-4470. doi: 10.1242/jeb.163832.
Mouth brooding is an extreme form of parental care in which the brooding parent carries the developing young in their buccal cavity for the duration of development. Brooding fish need to compensate for the brood weight on the anterior portion of their body. For fishes with a compartmentalized swim bladder, gas distribution between the chambers may aid in regulating buoyancy during brooding. To test this hypothesis, we took radiographs of to compare the swim bladder morphology of gravid, mouth-brooding and recovering females. Following spawning, females carry developing fish in their buccal cavity for ∼2 weeks, resulting in a larger and rounder anterior swim bladder compartment. Comparatively, the swim bladder of gravid females is long and cylindrical. Using small beads to mimic brood weight and its effects on female buoyancy, swim bladder changes were induced that resembled those observed during brooding. Immediately after releasing their fry, brooding females swim at a positive angle of attack but correct their swimming posture to normal within 5 min, suggesting a rapid change in swim bladder gas distribution. These data provide new insights into how swim bladder morphology and swimming behavior change during mouth brooding, and suggest a compartmentalized swim bladder may be a morphological adaptation for mouth brooding.
口育是一种极端的亲代抚育形式，在这种形式中，亲代在幼体发育期间将发育中的幼体置于口腔中携带。口育鱼类需要补偿其身体前部的育雏重量。对于具有分隔式鳔的鱼类，鳔腔之间的气体分布可能有助于在口育期间调节浮力。为了验证这一假设，我们对怀孕、口育和产后恢复的雌性鱼类进行了X光检查，以比较它们鳔的形态。产卵后，雌性在口腔中携带发育中的幼鱼约2周，这导致前鳔腔更大且更圆。相比之下，怀孕雌性的鳔长且呈圆柱形。使用小珠子模拟育雏重量及其对雌性浮力的影响，诱导出了与口育期间观察到的类似的鳔变化。口育雌性在释放幼鱼后立即以正攻角游泳，但在5分钟内将游泳姿势纠正到正常，这表明鳔内气体分布迅速变化。这些数据为口育期间鳔的形态和游泳行为如何变化提供了新的见解，并表明分隔式鳔可能是对口育的一种形态适应。
