Defense (1) Flashcards
Simon
Extrinsic ecological causes of mortality
- accidents
- predation (defense mechanisms)
- diseases (immune system)
- environmental stressors (tolerate, resist and repair)
Ageing (Intrinsic)
- degeneration of systems, cells and molecules
- can be influenced by extrinsic factors
- can be repaired to a point
Avoiding predators
- Diurnal/ vertical migration (in ground)
- Camouflage
Main 2 types of camouflage
- Crypsis
- Masquerade
Crypsis def
when colour or behaviour is employed to prevent detection when in plain sight
Masquerade def
recognition is prevented by resembling an uninteresting object
5 types of crypsis
- Background matching
- Countershading
- Obliterative shading
- Disruptive coloration
- Distractive markings
Background matching def
appearance generally matches the colour, lightness and pattern of background. Can be very specific
Countershading def
where the upper body of the animal is darker than the bottom, which cancels out creation of shadows in directional light
Obliterative shading
countershading obliterates (disguises) 3D form
Disruptive coloration
when markings create the appearance of false edges and boundaries, making it difficult to detect or recognise animal’s
true outline and shape
Distractive markings
Direct the ‘attention’ or gaze of the receiver from traits that would give away the animal (such as the outline)
Dissuading and repelling predators methods
- Flash colouration
- Warning colouration (Aposematism)
- Allomones (Chemicals)
- Venom & other chemicals
Aposematism
(Warning colouration)
- contradicts cryptic colouration
- warns predator that prey item is unprofitable
Allomones eg. (anti-feeding & anti-fouling)
- Neurotoxins (nemerteans)
- Sulphuric acid (shell-less mollusks)
- Hydrogen cyanide (Biolum millipedes)
Nemerteans
Ribbon worms
Venom & other chemicals eg.
- Cnidocytes
- Bombadier beetle
Anti-fouling (Callyspongia pulvinata) chemicals inhibit fouling by…
- Disrupting the biofilm by killing diatoms
- Inhibiting larval settlement & survival of polychaete larvae
- Can release chemicals into water - not restricted to animals touching the sponge
Externa physical threats can be overcome by
– Avoidance (daily activity patterns or camouflage)
– Dissuasion (strong outer coverings, chemicals that may be linked with warning colouration, or that prevent fouling or predation)
– Repellence (may utilise mechanisms that are usually used for feeding, or which simply frighten potential predators)
Dissuasion
Trying to persuade something to not take part in an activity
