Electroreception in Fish

The advantages & function of electroreception in various species of fish

Revett SaffoMolli Simpson Anthony Baldrica

Exploration

Use in communication Patterns of electroreception among fishes

Including variations in differing environments Electroreception DetectionConservation

Definition

Electroreception: a biological ability to perceive natural electrical stimuli. Often attributed to aquatic vertebrates

Functions of Electroreception Communication Predation Awareness

One example of an aquatic animal using electroreception comes from the Scyliorhinus canicula, more commonly known as small spotted catshark

Hammerhead Shark The Hammerhead

shark is an electroreceptive species An example of a

far-evolved electroreceptive fish with dense pore abundance

Species of Interest Subclass: Elasmobranchii

Small Spotted CatsharkAfrican Electric Catfish

Malapterusrus electricus South African Bulldog

Mormyrid fish: Marcusenius marcolepidotusMarcusenius altisambesi & Mormyrus rum

Support from Literature: Temporal patterning of electric organ discharges in theAfrican electric catfish, Malapterurus electricus (Rankin and Moller 1992)

Showed variations in electric organ discharge (EOD- electric discharge generated by the electric organ) depending on the fish that Malapterurus electricus (electric catfish) was around

Based on previous experience with the other fish, EOD varies in pattern and pulses

Environment, time of exposure, and predator/prey relationships effected the EOD response of M. electricus

Carassius auratus (goldfish) and Oreochromis niloticus (tilapia)

Avoided M. electricusContact was brief since C.

auratus and O. niloticus fled when M. electricus was present

Polypterus palmas (bichir)Both are bottom dwellersP. palmas freezes in response

to M. electricus Contact time is longerLong duration EODBrief trains with long-train

intervals

Clarias (airbreathing catfishes)

• Predator• High EOD• Great number of EOD

pulses• High frequency• Accompanied with visual

displays

EOD Volley TypesDisturbance

Responses to brief encounters C. auratus, O. niloticus, and P. palmas

DefensiveResponses to attacks Clarias

FeedingHigh and long frequency when feeding

Support from Literature:Electrocommunication behaviour during social interactions in two species of pulse-type weakly electric fishes  (Mormyridae) (Gebhardt et al, 2012)

Electroreception has been adapted for communication behaviors in mormyrids

Resting behaviors:Mormyrus rume

Decrease EOD Remain in individual shelters,

not visible to othersMarcusenius altisambesi

Found in large groups Both species exhibited EOD

synchronization in resting conditions

EchoingIn general, when fishes in groups

communicate via electroreception a echo is produced

The echo has various functions including aggressive displays, courtship signals, and jamming avoidance

M. rume and M. altisambesi respond to the echo produced

Echoing is advantageous when EODs are colliding since fishes will respond by not overlapping EODs A fish produces an EOD right after its neighbor where the EOD

occurs during a time when the neighbor will be silent and the other wont produce another EOD and so no overlap occurs

Synchronization Definition:

“Temporal correlation of electric discharges between individuals of a group is a complex social interaction, which both species displayed during foraging.” (Gebhardt et al., 2012)

M. altisambesi showed positive signaling between group members

M. rume showed similar mechanism where both fishes simultaneously emit similar EOD patterns

Fixed-order SignalingDifferent than synchronization Rather then occurring between two fishes

(synchronization), this occurs between the whole group

Three or more fish repeat order of their EODs relative to one another more than four times in a row

Further decreases overlap because each fish would have its own time to conduct their EODEOD may not be a problem when looking at only two

fishes, but looking at groups it is advantageous for fishes to have their own time to eliminate overlap.

M. altisambesi implies that the species has a stronger group cohesion supported by different EODShorter EODs are advantageous because it decreases

the probability of EODs overlapping.

Fixed-order Signaling

a. Marcusenius altisambesi

b. Mormyrus rume

Relationship to EcologyM. rume used a discharge behavior that functioned

as an agonistic signal. M. altisambesi are more social and less aggressive

then M. rume evident by the lack of EOD aggressiveness pattern.

M. altisambesi sociality may be related to its ecology which live in streams where floods increase the amount of potential habitat area.

Thus, this entails that competition for spawning sites may decrease which decreases aggressive interactions. M. rume has not adapted this type of behavior which means that aggressiveness increases in the species for territories and mates.

Applications and Value to current

research

How is electroreception related to biodiversity?

Conservation efforts exist in fishes that possess electroreceptionGymnotiform knife fishes ElasmobrachiiSea Lamprey

Electro-receptive fish important to biodiversity

Gymnotidae (electroreceptive fish)

Use electrosensory organs to detect prey within close range (Maclver, 2001) Implications

water conductivity affects prey capture via electrosensory organs

Food web relies on predator-prey interaction

Sea Lamprey control

Sea Lamprey (petromyzonmarinus) Highly predatory,

invasive species of Great Lakes

Important species in conservation management

Elasmobranchii

ElasmobranchiiK-selected

Slow grow, long gestation, late maturity, and low fecundity

Highly trophicA study done by R.A Martin, 2005 suggests some

species susceptible to endangerment or extinctionSpecies with limited geographic ranges prone to

extinctionSpecies who breed in sea at risk to be endangered “As K-selected creatures that compete for aquatic

resources against humans who widely regard them to be dangerous vermin, freshwater and euryhalineelasmobranchs present significant challenges to conservation biologists” (Martin, 2005).

Tools for Conservation in Electroreceptive fish

ERA’s (ecological risk assessment) (Gallagher et al., 2012)Behavior

Movement Migration

Fishing efforts and exploitation Molecular tools (Dudgeon et al., 2012)

Genetic applications Help understand needed conservation management

with use of molecular genetics

23

SummaryIncreased capabilities due to electroreception

Communication & AwarenessSynchronizationEchoingFixed-order Signaling

Predation Environment & time of exposure effect EOD

EOD types: Disturbance, Defense, & Feeding

Conservation efforts exist Important to biodiversity Important to food web

23

24

Future ResearchM. altisambesi and M. rume’s echoing

techniquieNot properly explained

(May decrease amount of EOD collision)

Elasmobranch’s pore abundanceCorrelation to feeding ecology and predator

avoidance not fully understoodConservation of Elasmobranchii

Electroreceptive behavior’s relationship to life strategies and thus, conservation

References Dudgeon, C. L., Blower, D. C., Broderick, D., Giles, J. L., Holmes, B. J.,

Kashiwagi, T., Krück, N. C., Morgan, J. A. T., Tillett, B. J. and Ovenden, J. R. 2012. A review of the application of molecular genetics for fisheries management and conservation of sharks and rays. Journal of Fish Biology, 80: 1789–1843.

Gallagher, A. J., Kyne, P. M. and Hammerschlag, N. 2012. Ecological risk assessment and its application to elasmobranch conservation and management. Journal of Fish Biology, 80: 1727– 1748.

Gebhardt, K., Böhme, M. and von der Emde, G. (2012), Electrocommunication behaviour during social interactions in two species of pulse-type weakly electric fishes (Mormyridae). Journal of Fish Biology. doi: 10.1111/j.1095-8649.2012.03448.x

Maclver, M.A. 2001. Prey-capture behavior in gymnotid electric fish: motion analysis and effects of water conductivity. Journal of experimental biology, 204: 543.

Martin, R. A. 2005. Conservation of freshwater and euryhalineelasmobranchs: a review.Journal of the Marine Biological Association of the United Kingdom, 85: 1049-1073.

Rankin, C. H. and Moller, P. (1992), Temporal patterning of electric organ discharges in the African electric catfish, Malapterurus electricus (Gmelin). Journal of Fish Biology, 40: 49–58. doi: 10.1111/j.1095-8649.1992.tb02553.x

26

Any Questions?