RQ24 - Consumption

At some point, categories like herbivore/parasite/predator break down. (For example, small insects that eat small amounts of large plants, over a long time, seem to conform to the definition of a parasite.) Why is this?

the categories are artificial constructs--the organisms don't care

Why are animals that eat seeds referred to as "seed predators?"

they consume all of the seed in a short period of time

What are the key differences between a parasite and a predator?

parasites are small relative to the victim and may not consume all of it

What is the difference between an herbivore and a carnivore?

Herbivores eat plants; carnivores eat animals.

In the experiment on mussels and blue crabs, what hypothesis do the data suggest, but not test?

Mussels can sense the presence of one or more water-born chemicals from crabs.

To study the impact of predation on prey populations, researchers study "natural experiments" that occur when predators are added or removed in a region. What is the key assumption behind this work?

Other factors that influence prey populations, like food availability, do not change.

If predators are removed from an area and prey population sizes do not chance, what can you conclude?

Predation is not a key factor limiting population size--something else is.

What's the difference between a standing defense and an induced defense?

Standing defenses are always present; induced defenses develop in response to a threat.

When females are preyed upon, the impact on the prey species' population size is much greater than when males are preyed upon. Why?

The dead females can't produce offspring.

Can a standing defense also be an inducible defense? (Hint: think about the mussel shell experiment.)

Yes--the amount of a standing defence can increase in response to presence of a threat.