A Novel Interception Strategy in a Miniature Robber Fly with Extreme Visual Acuity.
Curr Biol 2017;
27:854-859. [PMID:
28286000 PMCID:
PMC5364399 DOI:
10.1016/j.cub.2017.01.050]
[Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Revised: 12/16/2016] [Accepted: 01/24/2017] [Indexed: 11/21/2022]
Abstract
Our visual system allows us to rapidly identify and intercept a moving object. When this object is far away, we base the trajectory on the target’s location relative to an external frame of reference [1]. This process forms the basis for the constant bearing angle (CBA) model, a reactive strategy that ensures interception since the bearing angle, formed between the line joining pursuer and target (called the range vector) and an external reference line, is held constant [2, 3, 4]. The CBA model may be a fundamental and widespread strategy, as it is also known to explain the interception trajectories of bats and fish [5, 6]. Here, we show that the aerial attack of the tiny robber fly Holcocephala fusca is consistent with the CBA model. In addition, Holcocephala fusca displays a novel proactive strategy, termed “lock-on” phase, embedded with the later part of the flight. We found the object detection threshold for this species to be 0.13°, enabled by an extremely specialized, forward pointing fovea (∼5 ommatidia wide, interommatidial angle Δφ = 0.28°, photoreceptor acceptance angle Δρ = 0.27°). This study furthers our understanding of the accurate performance that a miniature brain can achieve in highly demanding sensorimotor tasks and suggests the presence of equivalent mechanisms for target interception across a wide range of taxa.
Video Abstract
Holcocephala fusca robber flies capture prey with a constant bearing angle strategy
The approach is proactively altered to “lock on” on to prey within 29 cm distance
The retina spatial resolution is 0.28°, but the object detection threshold is 0.13°
The fly’s stereopsis range is estimated to be ∼26 cm
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