Week 10- Thermal Physiology and Anti-Predator Behaviour

Define antipredator behaviour

Any behavioural mechanism that prey use to avoid predators

Name the main antipredator behaviours

Fight or escape

Crawling out of a predators digestive tract

Counter-attack of a predator

Avoiding predator detection

Signalling unpalatability/toxicity

Diluting individual risk or confusing predators in a social group

Desrie burst swimming

High energy burs either from rest or during periods of steady state swimming

Important for predator prey

Can be categorised as c or s starts

What are the three many parts of escaping predators

Latency, turning rate, distance

What is supramaximal exercie

exceeds MMR and AS, requires anaerobic glycolysis to meet ATP demand

Fast start responses are dictated through neuronal pathway what are they responsible for

• Detecting and processing incoming sensory info about an imminent predator attack

• Stimulating motor neurons and muscles involved in repsonse

What is a synapse

Location for signalling between neurons

What are the two types of synapse

Electrical and chemical

Why are electrical synapses used in crayfish escape?

They are very fast and bidirectional, allowing instant tail flip to escape danger.

What is a mauthner cell

Fish equivalent of crayfish lateral giant neuron

Occurs in pairs one on either size of hind brain

Explain fish fast start

• M cell on side of body stimulated connected to motor neurons

• Fish turn away from threatening stimulus

• Generates second axial bend motor neurons connected to muscles on opposite flank connect

• Fine tuned highly rapid response occures through combination of excitory anf inhbitoy mechnaims so muscles dont work against one another

What are m cell synpases

Combination of electrical and chemical synapses
with neighbouring neurons, and thus exhibit
greater plasticity through time in response to

What is the importance of temperature for anti predator behaviour

• Burst performance tends to increase with rising temp due to impacts on muscle performance and power output

• Modulated by thermal history of individual

• Often think of higher temps as bad for animals

What was used to study temperature altering escape performance

Used goldfish

Found shorter escape latency and greater escape probability with higher temp

But… responses were less accurate at higher temp

How is fish escape speed linked to metabolism?

Fish that recover faster from exercise (high aerobic capacity) have faster reaction times during escape responses.
Temperature had no effect on this relationship.

While prey are affected in terms of escape behaviour what happens to the predator

Study examined impacts of elevated temp on both prey and predators

• Prey experienced decreasing escape speed and distances

• Mixed effects on predators including decreasing reaction distance but also increased max attack speed

What is ectothermy

Strategy in which animals body temp is determine by equilibration with the environment thermal conditions

What are the two types of ectotherms

Eurythermal and stenothermal

What does eurythermal mean

Species that can function over a wide range of body temps

What does stenothermal mean

Species with comparatively narrow thermal ranges at which they can survive

Describe a method used to test thermal preference in ectothermic aquatic species

Shuttle box system- allows temp in two chambers to be manipulated to look at when avoidance behaviour is initiated

What are the three types of time frame for thermal change

Acute, chronic and evolutionary

What is acute thermal change

Prompt responses to thermal
change (e.g. heat waves)

What is chronic thermal change

acclimation/acclimatization to a
prolonged thermal change (e.g. increases
in seasonal temperature means)

What is evolutionary thermal change

Changes in physiology
through selection on genes over many
generations exposed to a changing
thermal environment (e.g. climate change)

What is resting metabouc rates relationship with body temp

Increases exponentially with body temp

What is Q10/ temp coefficient

The multiplicative factor by which metabolic rate increases
when the body temperature is increased by a standardized
increment of 10◦C
Formula for temperature coefficient:
Q10 = RT / R(T-10)

RT = rate at body temperature (T)
R(T-10) = rate at a body temperature
10◦C lower than T

*Rule of thumb, Q10 of ectotherms
usually between 2 and 3

In the acclimation potential what is compensation

Long-term tendency
for the rate to return to its original
level despite continued thermal change

In the acclimation potential what is partial compensation

If the rate only
partially returns to its original level
(most common)
• X→Y: temp
change of
33-16C
• Y→Z: 5 wks
acclimation

What is chronic acclimation potential change and why are we hopeful

There has been Acclimation to predicted ocean warming through developmental plasticity in tropical reef fish

What is the acclimation potential mechanism

Animals can alter the amounts of
key, rate-limiting enzymes involved
in glycolysis (i.e. anaerobic
metabolism) as well as the Krebs
cycle and electron-transport chain
(i.e. aerobic metabolism)

How does life history affect acclimation?

Long-lived, mobile species acclimate better to temperature changes than short-lived, sedentary species.

How do enzymes respond to temperature in different fish?

Cold-adapted Antarctic fish have enzymes that are more temperature-sensitive than warm-water fish (e.g. mullet).

What does a performance curve tell us

What temp range maximises a species performance in its physiology

What are the stages of a performance curve

1 = performance peak

2 = pejus temperatures (i.e. range of
temperature when performance declines
precipitously, environment causes
performance limitations)

3 = critical temperature (point at which SMR
reaches MMR, so AS = 0)

4 = lethal temperatures

What is the hypothesis for why animals undergo thermoregulation

So that cells and tissues can improve performance through thermal specialiastion at maintained body temp

What is behavioural thermoregulation

Using behavioural mechanisms to maintain a relatively constant body temo

e.g. reptile basking in sun, fish moving around to different thermal regimes in lake

What are the problems with endothermy

Energetically costly