Intraspecific agonistic arm-fencing behavior in the Antarctic keystone sea star Odontaster validus influences prey acquisition

Marine Ecology Progress Series

James B. McClintock¹  Robert A. Angus¹  Charles D. Amsler¹  Bill J. Baker¹  Christina P. Ho¹ 

关键词: Keystone species;    Agonism;    Arm-fencing behavior;    Predation;    Sea star;    Odontaster validus;   

DOI  :  10.3354/meps07710

学科分类：海洋学与技术

来源: Inter-Research

【 摘 要 】

ABSTRACT: The importance of intraspecific social behaviors in mediating foraging behaviors of marine invertebrate keystone predators has received little attention. In laboratory investigations employing time-lapse video, we observed that the keystone Antarctic sea star Odontaster validus displays frequent agonistic arm-fencing bouts with conspecifics when near prey (injured sea urchin). Arm-fencing bouts consisted of 2 individuals elevating the distal portion of an arm until positioned arm tip to arm tip. This was followed by intermittent or continuous arm to arm contact, carried out in attempts to place an arm onto the aboral (upper) surface of the opponent. Fifteen (79%) of the 19 bouts observed occurred near prey (mean ± 1 SE, 13 ± 1.6 cm distance to prey; n = 13). These bouts lasted 21.05 ± 2.53 min (n = 15). In all 5 bouts that involved a large individual (radius, R: distance from the tip of an arm to the center of the oral disk; 45 to 53 mm) competing with either a medium (R = 35 to 42 mm) or small (R = 25 to 32 mm) individual, the large sea star prevailed. The only exception occurred in 2 instances where a medium-sized sea star had settled onto prey and was subsequently challenged by a larger individual. Here, the outcomes were reversed in favor of the medium-sized individuals. These complex social behaviors mediating intraspecific competition for the acquisition of prey by a keystone predator are likely to have significant ramifications in terms of individual fitness, population structure, and community composition.

【 授权许可】

Unknown