Where art thou?

Navigation is vital to the survival of many of the world’s creatures. Most animals possess multiple sensory systems to assist them in navigating the world (Schumancher et al. 2017).  Electric fish are no exception to this rule.  Navigation,  like communication, assist electric fish in forging for food, mating for mates, and refuge away from possible predators.  Electric fish relay on their electric organ especially since they typically live in a muddy, freshwater, environments which limits the amount of sensory information they can receive through their eyes.

Electrolocation is the ability to detect electric fields (Peng et al. 2017). There are two types of electrolocation: active and passive.  Active electrolocation is when the organism produces their own electric field. Active electrolocation is important in electric fish because it allows them to find prey and navigate to other locations. Passive electrolocation, is when an organism detects the electric field that other animals made (Peng et al 2017). This is also important in electric fish because it allows them to pick up on electric fields that a predator makes due to muscle contractions.    

Electrolocation patterns in Electric Fish

Tlb94Weakly Electric Fish Navigating Electric FieldsCC BY-SA 3.0

          In this post, I am going to focus on two different types of navigation: Egocentric and Allocentric navigation.  Egocentric navigation is when you decide where objects are with respect to where you are (Harvard 2019).  From a physics standpoint it would be making the organism the origin on the Cartesian plane. Where as in Allocentric navigation an organism uses external cues, such as landmarks, to make a decision of where the location of another object is (Harvard 2019).  The study that Schumander and colleagues completed investigated the type of navigation that the weakly electric fish Gnathonemus petersii performed.

          In Schumander’s study 9 out of the 10 electric fish choose to take the egocentric route opposed to the allocentric route (Schumander et al. 2017.).  All the fish were able to navigate the maze after they were trained which also supports that G.petersii uses egocentric navigation.  This is not to say that these fishes only relay on internal cues,  because, as previously stated, navigation relays on the cooperation of multiple sensory systems. One problem that Schumander detailed is that there may be a conflict between global and local landmarks since they changed the location of landmarks inside the tank (Schumander et al. 2017).  Climate change may lead to different navigation strategies for these species.

           Global climate change may cause multiple species of move out of established environments because those environments may be compromised with the rising in water temperatures (Leandro et al. 2018). The electric fish would have to navigate to unfamiliar waters which requires them to “learn” new landmarks which may turn make them relay on allocentric navigation in the Schumander paper stated that under extreme pressure G.petersii would be able to change their node of navigation (Schumander et al. 2017). Electric fish must have good communicative abilities when navigating to new waters to avoid predation and an unfavorable environment. If electric fish are unable to adapt to the rising in water temperatures, then I would not be surprised if many electric fish go extinct .  

Literature Cited:

1. Allocentric vs. Egocentric Spatial Processing. http://www.nmr.mgh.harvard.edu/mkozhevnlab/?page_id=308

2. Becker LA, Crichigno SA, Cussac VE. Climate change impacts on freshwater fishes: a Patagonian perspective. Hydrobiologia. 2018;(1):21. doi:10.1007/s10750-017-3310-4

3. Schumacher S, von der Emde G, Burt de Perera T. Sensory influence on navigation in the weakly electric fish Gnathonemus petersii. Animal Behaviour. 2017;132:1–12. doi:10.1016/j.anbehav.2017.07.016

4. Jiegang Peng;Yue Zhu;Tao Yong. Research on Location Characteristics and Algorithms based on Frequency Domain for a 2D Underwater Active Electrolocation Positioning System. Research on Location Characteristics and Algorithms based on Frequency Domain for a 2D Underwater Active Electrolocation Positioning System. 2017;(4):759.

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