Transcript Support from Literature: Malapterurus electricus

Electroreception in
Fish
The advantages & function of electroreception in
various species of fish
Revett Saffo
Molli Simpson
Anthony Baldrica
Exploration
 Use in communication
 Patterns of electroreception among fishes
 Including variations in differing environments
 Electroreception Detection
 Conservation
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 Catshark
 African Electric Catfish
 Malapterusrus electricus
 South African Bulldog
 Mormyrid fish: Marcusenius marcolepidotus
 Marcusenius altisambesi & Mormyrus rum
Support from Literature:
Temporal patterning of electric organ discharges in the
African 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. electricus
 Contact was brief since C.
auratus and O. niloticus fled
when M. electricus was present
Polypterus palmas (bichir)
 Both are bottom dwellers
 P. palmas freezes in response to
M. electricus
 Contact time is longer
 Long duration EOD
 Brief trains with long-train
intervals
Clarias (airbreathing catfishes)
• Predator
• High EOD
• Great number of EOD pulses
• High frequency
• Accompanied with visual
displays
EOD Volley Types
 Disturbance
 Responses to brief encounters
 C. auratus, O. niloticus, and P. palmas
 Defensive
 Responses to attacks
 Clarias
 Feeding
 High 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 others
 Marcusenius altisambesi
 Found in large groups
 Both species exhibited EOD
synchronization in resting
conditions
Echoing
 In 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 Signaling
 Different 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 EOD
 EOD 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 EOD
 Shorter EODs are advantageous because it decreases the
probability of EODs overlapping.
Fixed-order Signaling
a. Marcusenius altisambesi
b. Mormyrus rume
Relationship to Ecology
 M. 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
electroreception
 Gymnotiform knife fishes
 Elasmobrachii
 Sea 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
Elasmobranchii
 K-selected
 Slow grow, long gestation, late maturity, and low fecundity
 Highly trophic
 A study done by R.A Martin, 2005 suggests some species
susceptible to endangerment or extinction
 Species with limited geographic ranges prone to extinction
 Species 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
Summary
 Increased capabilities due to electroreception
 Communication & Awareness



Synchronization
Echoing
Fixed-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
Future Research
 M. altisambesi and M. rume’s echoing techniquie
 Not properly explained

(May decrease amount of EOD collision)
 Elasmobranch’s pore abundance
 Correlation to feeding ecology and predator avoidance
not fully understood
 Conservation of Elasmobranchii
 Electroreceptive behavior’s relationship to life
strategies and thus, conservation
24
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: 10491073.
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
Any Questions?
26