Federica Miano, Seyed Saeed Asadzadeh, Fredrik Ryderheim, Anders Andersen, Thomas Kiørboe
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引用次数: 0
Abstract
Some planktonic organisms can remotely sense and evade predators by powerful escape jumps. Remote perception typically happens through the fluid disturbance generated by the approaching predator or its feeding current. In copepods and ciliates with mechanosensors, the perception and jump mechanisms are well understood. But how some flagellates perceive the fluid disturbance and achieve similar relative speeds with only two flagella is less explored. Here, we examined the ability of three haptophytes, Chrysochromulina simplex, Prymnesium polylepis, and Prymnesium parvum, to sense and evade the fluid disturbance generated by the feeding current of a copepod nauplius. Chrysochromulina simplex has a long haptonema (14 cell diameters), while the haptonema of the two other species are shorter (1 and 0.5 cell diameters). Only C. simplex responded to the fluid disturbance by fleeing at high speeds. The jump mechanism consists of two phases: the rapid coiling of the haptonema that pulls the cell about two cell diameters in the direction of the haptonema, followed by flagellar reversal and high‐speed swimming (70 cell lengths per second) in the opposite direction. We rationalize cell displacements and escape speeds from haptonema and flagellar kinematics and fluid dynamics. Using a microfluidic channel, we demonstrate that the component of the fluid signal that triggers the jumps is the maximum deformation rate rather than the magnitude of deformation. High‐speed escape jumps may be an avoidance mechanism evolved by haptophytes with long and coiling haptonema, while species with shorter haptonema may use other defense mechanisms, such as stealth and toxicity.
期刊介绍:
Limnology and Oceanography (L&O; print ISSN 0024-3590, online ISSN 1939-5590) publishes original articles, including scholarly reviews, about all aspects of limnology and oceanography. The journal''s unifying theme is the understanding of aquatic systems. Submissions are judged on the originality of their data, interpretations, and ideas, and on the degree to which they can be generalized beyond the particular aquatic system examined. Laboratory and modeling studies must demonstrate relevance to field environments; typically this means that they are bolstered by substantial "real-world" data. Few purely theoretical or purely empirical papers are accepted for review.