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Anti-predator Behavior in
Aquatic Invertebrates
Eric Hanson
Papers
Learned recognition of predation risk by Enallagma damselfly larvae
(Odonata, zygoptera) on the basis of chemical cues
Responses of larval dragonflies to conspecific and heterospecific
predator cues.
Behavioral Differences between Enallagma species (Odonata) influencing
differential vulnerability to predators
Antipredator responses and the perception of danger by mosquito larvae
Mutual predation in assembled communities of Odonate species
Introduction
• Antipredator responses are indicated by a
reduction in movement or increased
refuge use
• Chemical cues provide sensory
information in bleak environments
• Cannibalism occurs in most species of
aquatic invertebrates
• Dragonfly larvae and most other aquatic
invertebrates prey upon smaller
conspecifics
Learned recognition of predation risk by Enallagma
damselfly larvae (Odonate, Zygoptera) on the basis of
chemical cues
Brian D. Wisenden, Douglas P. Chivers, and R. Jan F. Smith
• Injury released chemical stimuli from conspecifics
represents a predation event
• Reduction of activity indicates anti-predator behavior
• A learned recognition of a novel predator cue
• Enallagma boreale – (one population was exposed to northern pike in its
natural environment and the other was not)
• 3 Experiments:
– Population differences: fig 1
– Learned recognition of a novel predator cue: fig 2
– Specificity of response to fish alarm cues: fig 3
Results
FIG. 1. Mean (±SE) change in frequency of feeding strikes, head turns, and walking
movements by damselflies that co-occur with pike and those that do not, following
exposure to a control of distilled water (W; open bars), pike stimulus (P; hatched
bars), or injured conspecific damselflies (D; solid bars). For each behavior, bars
with different letters are significantly different from others in that population (KW
post hoc multiple comparison test, P < 0.05).
FIG. 2. Right: Mean (±SE) change in frequency of feeding strikes, head turns, and walking
movements for damselflies presented with chemical stimuli from pike and distilled water
(W; open bars), pike and injured fathead minnows (M; hatched bars), or pike and injured
conspecific damselflies (D; solid bars). Left: Mean (±SE) change in frequency of feeding
behaviors for the same damselflies when presented later with chemical stimuli from pike
alone. Bars denote conditioning stimuli described above.
FIG. 3. Mean (±SE) change in frequency of feeding strikes, head turns,
and walking movements for damselflies presented with distilled water (W;
open bars), chemical stimuli from injured swordtails (S; hatched bars), or
chemical stimuli from injured conspeciflc damselflies (D; solid bars).
Conclusions
• In experiment 1: damselflies that co-occur
with pike showed anti-predator behavior to
just pike stimuli
• Single presentation learning (experiments
1 and 2)
• E. boreale was able to learn anti-predator
behavior between heterospecific chemical
cues and only pike stimuli
Responses of larval dragonflies to
conspecific and heterospecific predator cues
Gavin Ferris and Volker H. W. Rudolf
• Larger larvae should represent a predation risk
to smaller larvae
• Plathemis lydia – breeds continuously providing
different instars over time
• Testing to determine if visual, chemical, or a
combination are used to determine predation
risk
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A perforated clear cylinder for control
A clear cylinder with a larger conspecific for visual cues
A perforated cylinder covered in tin foil for chemical cues
Anax junius was used as a heterospecific predator in each group
Fig. 1. Mean number of squares occupied by small P. lydia larva for each treatment
displayed after correcting for the signifi cant day (block) effect. Control = no
predator, Chem = chemical cue, Visual = visual cue, Both = chemical + visual cues
from conspecifi c cannibals respectively, Heter. Pred = chemical and visual cues
from the heterospecific predator A. junius . Treatments with different letters are
significantly different after Dunn – Sidak correction ( P < 0.05).
Fig. 2. Mean activity rate of small P. lydia larva for each treatment displayed
after correcting for the significant day (block) effect. Activity rate was calculated
as the total number of movements per minute observed over a 20-min period.
Fig. 3. Mean per capita consumption rate of small P. lydia larva displayed after
correcting for the significant day (block) effect. Consumption rates were
calculated as the number of prey consumed during a 24-h period.
Conclusion
• Day block effect – significant differences in data
collected for each day they ran the experiment
• Lacking strong significant differences
– P. lydia showed an increase in activity to conspecific
predator, but a decrease with a heterospecific (A.
junius) predator
– Differing foraging strategy (bottom sprawlers or sitand-wait predators) – movement is an appropriate
response to a chemical cue in this species
– Decreased activity when A. junius is present show
that they distinguish between heterospecific and
conspecifics, with A. junius representing a more
active predator (will hunt P. lydia)
Antipredator reponses and the perception of
danger by mosquito larvae
Andrew Sih
• Accurate anti-predator responses is important to
the evolution of the behavior
• Two species of mosquito: Aedes aegypti and
Culex pipiens – with Notonecta undulata
(backswimmer) as the predator
• A. aegypti should be more susceptible to
predation by N. undulata than C. pipiens
because they don’t ordinarily encounter them
• Quantified movement and spatial distribution by
mosquito as a function of N. unduata density
(fig 1)
Methods
• 100 mosquito larvae were introduced into
the center of the container, N. undulata
does not like corners
• Spatial movements were mapped every 30
min, and remaining mosquito larvae were
counted every 60 min
• Experiments were repeated 5 times with 6
hour intervals or when there was <20
mosquito larvae
FIG.1. For two species of mosquito
larvae, Culex pipiens and Aedes
aegypti, the percent of time spent
(A) moving and (B) in the central
50% of plastic laboratory tubs, as a
function of the density of a
predator, Notonecta undulata, and
the presence of refuges.
(Notonecta was most common in
the tub centers and had the highest
capture success there.) Each point
shown is a mean + 1 standard
error. Horizontal lines below
predator densities connect
treatments that do not differ
significantly (T-method).
Note: With only one Notonectid,
Culex reduced their movement by
79.5% and their use of center by
85.1%, and Aedes were only
15.5% and 18.3% respectively
Conclusion
• Culex was killed at a significantly lower rate than
Aedes
• Culex showed a significantly more precise antipredator response than Aedes
• When chemical cues were added, Culex showed
a strong response to conspecifics + predator cue
(where 60 mosquito larvae were consumed) –
none had a significant effect on Aedes
• Both species showed avoidance, and not just
escapism
• Culex possibly uses chemical cues to more
accurately respond to a predation risk
Behavioral differences between Enallagma species
(Odonata) influencing differential vulnerability to predators
Mark A. McPeek
• 4 species of damselfly larvae studied:
Fishless lakes:[E. aspersum, E. boreale]
Lakes w/fish [E. vesperurn,E. geminatum]
• Damselflies that occurred in fishless lakes
displayed more conspicuous behaviors and
moved more with longer resting periods than did
damselflies that occurred in lakes with fish
• Indicates a learned response to the presence of
fish by damselfly larvae
N=no predator
A=Anax junius
B=bluegill
Ea = E. aspersum, Eb = E. boreale, Ev = E. vesperurn, Eg = E. geminatum.
Mutual predation in assembled communities
of odonate species
James V. Robinson and Gary A. Wellborn
• Each of 6 ponds contained equal numbers and equal
size distributions of 6 species of odonates
• 3 ponds were exposed to A. junius as an additional
predator
• In Anax-free ponds, smaller individuals experienced the
highest mortality
• In ponds with Anax, predation was species dependent.
P. lydia buried itself to avoid A. junius
• Active individuals may grow larger, but pose a greater
predation risk than individuals that display anti-predator
behavior
• Anti-predator behavior increase maturation time, and
ultimately cuts into reproductive fitness as adults (not as
much time spent as adult)
Final Conclusions
• Anti-predator behavior in invertebrates occurs with either
visual or chemical cues in their environment
• The more accurate the behavior, the best cost to fitness
ratio occurs
• Invertebrates can learn to associate novel predatory
cues with a predation event, and respond by escapism
or avoidance
• Predator/prey relationships that evolved together have
the most significant anti-predator reactions\
• Learning occurs fast; usually after only one encounter
• I’m running an experiment to test whether or not A.
junius will display anti-predator behavior to conspecifics
and if they can learn to associate a novel predator cue
with predation risk