Sensing and Responding to the Environment

Operant vs. classical conditioning: Both are types of associative learning, so two experiences become associated with each other. In operant conditioning, the animal does something itself—it eats something, it pulls something, it hides, it doesn’t hide, you get the idea. In classical conditioning, two things happen to the animal and they become associated in the animal’s brain.

Movement and Migration

Kinesis vs. taxis: They are both types of movement in response to a stimulus, but kinesis is not directional and taxis is. The way to remember this is if you need to go somewhere, take a taxi to get you there. You wouldn’t take a kinesi, would you?

Finding Food

Animals don’t calculate Optimal Foraging Theory equations while they are out finding food. They do it ahead of time on their high-powered computers to figure out where they should look. Just kidding. The Optimal Foraging Theory is just a way for scientists to describe the natural foraging behavior of animals and predict how they behave.

Defense

Mimicry is a really cool behavior in the animal world, but it is also a little tricky. Mimicry happens because evolution selects for mimics because animals that mimic dangerous animals have better survival and more reproductive success than those that don’t. Your cat has probably never even seen a snake, but it has an innate reaction to being threatened that makes it look like a snake because that reaction has been selected over many generations.

Communication

Pheromones are sometimes described as hormones. The difference is that hormones work inside one individual’s body, signaling to the organs to do something and pheromones work outside the body to communicate to other individuals.

Social Systems and Altruism

Kin selection favors altruism when more total offspring can be produced for the family group and assumes the altruist is helping the relatives survive. An individual that does not actually help raise offspring or otherwise enhance relatives’ survival is not an altruist just because he or she does not reproduce.

Mating Behavior

A common misconception is that monogamy means mating for life. It doesn’t. Monogamy means mating with one partner for a breeding season. Usually monogamous animals mate with a different partner the next breeding season, not the same partner over and over again for life. Sorry, but it’s true.

Polygyny and polyandry are easy to get mixed up. The prefix "poly" means many or multiple. "Gyn-" relates to females and "andr-" means males. So poly + gyny = many females (one male mating with multiple females) and poly + andry = many males (one female mating with many males). One way to remember this? Ladies go to the gynecologist, but men don’t.

Finding a Mate

Intersexual and intrasexual selection: The prefixes inter- and intra- come up in biology quite a bit. Inter means "between," as in the interstate is the highway that goes between two states. Intra means "within," as in intramural sports, which are played within one school/league/club. So intersexual selection is selection between the two sexes—females selecting males—and intrasexual selection is selection within one sex—the strongest or most competitive males get to mate with the females.

Raising Offspring

Where do these weird letters come from? The r stands for growth rate of the population, which is maximized in r-selected species. K stands for carrying capacity, which is the upper limit on the population. If everyone is well cared for and survives into adulthood, then the population is limited by the carrying capacity of the environment.

Not every animal species is either r or K-selected. There is some middle ground too, but these are the extremes that demonstrate the range of lifestyles.