BIOLOGY 220 LECTURE #19 - Animal defenses 1- Introuction and Nervous System - 11-16-07

BIOLOGY 220 LECTURE #19 - Animal defenses 1- Introuction and Nervous System - 11-16-07

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Unformatted text preview: BIOLOGY 220 LECTURE #19 ANIMAL DEFENSES 1: INTRODUCTION AND NERVOUS SYSTEM ANIMAL DEFENSES AGAINST PREDATORS 2 When an animal is attacked by a predator, the attack is generally lethal . o Whether the attack is not directly lethal, injuries as a result of being attacked might lead to death later ( indirectly ) ANIMAL DEFENSES AGAINST PREDATORS 3 Coloration Spines Mimicry Behavioral Chemical Chemical Visual Morphological o Spine Vocal o Sort of like behavior Behavioral ANIMAL DEFENSES AGAINST PREDATORS 4 Chemical Defenses If something is poisonous when eaten, the defense (in the form of a toxin or other chemical defense), the defense is not effective for the individual (which is eaten), but it is effective in protecting the population of that individuals species (predator learns not to eat that species) Deterrent Skunk ANIMAL DEFENSES AGAINST PREDATORS 5 Chemical Defenses Most of the chemical defenses (especially toxins) are effective at the population level o Not effective for the individual ANIMAL DEFENSES AGAINST PREDATORS 6 Visual Defenses Type of visual defense #1: Crypsis Making yourself look just like your environment so that no possible predator can find you Type of visual defense #2: Aposematic Coloration (Warning Coloration) A method of warning other predators that you are dangerous (poisonous) coloration Visual defenses are often completely cryptic or visual defenses are coupled with a chemical defense ANIMAL DEFENSES AGAINST PREDATORS 7 Visual Defenses Visual defenses have led to the evolution of mimicry Batesian Mimicry- (harmless palatable look alike toxic models [false poison]) Mullerian Mimicry (mimics look alike and pose danger [real poison]) Really bright blues, reds, and yellows poisonous colors An insect has a certain type of pigmentation that will make it less likely to get eaten because something else has the same kind of pigmentation More pigmentation more likely to grow and reproduce. From the predators perspective, it is a learned process if I eat this, its going to make me sick o If the predator is apart of a highly sociable species that might hunt/forage for food together, then the species learns to not eat certain things o If the predator hunts/forages alone, the predators species is not going to learn to not eat certain things Batesian mimicry only works under certain circumstances: o Have to have similar coloration/physical characteristics (share some characteristic) o There has to be more toxic individuals in a group than non-toxics When we talk about mimicry in Biology, we are talking about two different individual species that look the same....
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BIOLOGY 220 LECTURE #19 - Animal defenses 1- Introuction and Nervous System - 11-16-07

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