1 of 25

Topic 8.1 Responses to the Environment

Study of interactions between organisms and environment

2 of 25

What is Ecology?

  • Study of interactions among living things
  • Includes interactions with environment
  • Focus on survival and behavior

3 of 25

7 Characteristics of Life

  • HOW MANY CAN YOU REMEMBER?

4 of 25

7 Characteristics of Life

  • Made of cells
  • Reproduce
  • Metabolize
  • Excrete waste
  • Maintain homeostasis
  • Grow and change
  • Respond to stimuli

5 of 25

Responding to the Environment

  • All organisms must respond to stimuli
  • Ensures survival and homeostasis
  • Central concept in ecology

6 of 25

Types of Responses

Physiological changes in response to stimuli are automatic bodily responses (increased heart rate, sweating, hormonal shifts)

  • happen inside the body

​

Behavioral responses are the observable actions or choices an organism makes in response to stimuli

  • outward results (what is done/interaction in response)

​

  • Both help survival
  • Many responses are a combination of physiological and behavioral responses

7 of 25

Physiological Responses

Immediate vs. Prolonged Responses

​

Different body systems handle various timelines of reaction:

  • Fast-Acting (Nervous System): Uses electrical signals and neurotransmitters for near-instantaneous but short-lived effects, such as pulling your hand away from a hot surface (reflex arc)
  • ​
  • Slow-Acting (Endocrine System): Releases hormones (like cortisol or adrenaline) into the bloodstream. These responses take longer to start but have prolonged, systemic effects on metabolism, mood, and energy

8 of 25

Examples

Stimulus

Primary System

Physiological Response Summary

Touching a hot stove

Nervous

Immediate withdrawal reflex; motor neurons trigger muscle contraction to pull away in milliseconds.

A sudden loud bang

Nervous

Startle response; instant spike in heart rate and heightened alertness via electrical impulses.

Low blood sugar

Endocrine

The pancreas releases glucagon, signaling the liver to convert stored glycogen into glucose for energy.

Dehydration

Endocrine

The pituitary gland releases ADH (antidiuretic hormone), signaling the kidneys to retain water and reduce urine output.

9 of 25

Behavioral Responses

Behavioral responses are the observable actions or choices an organism makes in response to a stimulus. While physiological responses happen inside the body (like a racing heart), behavioral responses are the outward results (what you actually do to interact with or change your environment)

  • These can be innate (instincts you're born with, like flinching) or learned (actions based on past experience, like checking your phone when it pings).

10 of 25

Examples

Stimulus

Animal

Instinctive Behavior

Summary

Shadow overhead

Fish / Frog

Diving/Scattering

Instantly swimming deeper or jumping into water to avoid a potential bird of prey.

Touch on the shell

Turtle / Snail

Retraction

Quickly pulling the head and limbs into a hard shell for immediate armor protection.

Heat on the skin

Dog / Cat

Flinching

Jerking the body away from a hot surface before the brain even fully processes "pain."

Object moving toward eyes

Horse / Human

Blinking

Snapping the eyelids shut instantly to prevent physical damage to the cornea.

Poking/Prodding

Pill Bug (Roly-Poly)

Rolling into a ball

Curling into a tight sphere to protect its soft underside from a predator.

Loud, sharp noise

Deer

Freezing

Stopping all movement instantly to blend into the background and assess the danger.

11 of 25

Plant Response: Phototropism

  • Plants grow toward light
  • Uses water pressure (turgor pressure)
  • Maximizes photosynthesis

12 of 25

Animal Response Example

  • Nocturnal animals active at night
  • Respond to sunlight changes
  • Helps avoid predators or heat

13 of 25

Communication Between Organisms

  • Organisms exchange information
  • Can change behavior of others
  • Essential for survival

​

​

Man trained birds to be afraid of him while wearing caveman mask

​

​

A Harvard Stadium Pigeon Prank That Pavlov Would Be Proud Of

​

14 of 25

Example: Acacia Tree Defense

  • Releases ethylene gas when eaten
  • Makes leaves taste bad
  • Warns nearby plants

15 of 25

Example: Warning Coloration

  • Bright colors signal toxicity
  • Triggers an avoidance response in predators
  • Predator Learning and Memory- a single negative experience (taste/sickness) creates a learned behavior
  • Increases survival

16 of 25

Fight-or-Flight Response

  • Triggered by threats/stressors
  • Releases hormones to illicit response
  • Increases heart rate & focus
  • Prepares organism to act

17 of 25

Behavior & Natural Selection

  • Behaviors increase fitness (increased reproductive success)
  • Can be innate or learned
  • Selected over time

18 of 25

Pollination Example

Bee pollination and flower color are an example of stimulus-response relationship:

  • vibrant, UV-reflective floral colors (stimulus) are perceived by bees, triggering a foraging behavior (response)
  • that leads to pollen transfer
  • Bees are specifically attracted to colors like purple, blue, and yellow, using these cues to find

19 of 25

Animal Communication

  • Signals: visual, sound, chemical
  • Used for dominance, food, mating

​

Examples:

  • Territory
  • Dominance
  • Food
  • Reproductive Success

​

​

20 of 25

Territorial Behavior

  • Animals mark territory with scent
  • Prevents competition
  • Increases reproductive success

​

Red Panda

21 of 25

Dominance

Wolf Pack- Alpha

22 of 25

Mating Behavior Example

  • Birds sing or build nests (bowers)
    • blue and as pretty as possible
  • Attract mates (best decorated)
  • Better displays = more success

23 of 25

Cooperative Behavior

Cooperative behavior mostly increases finess of individuals and populations

  • Organisms work together
  • Increases survival
    • safety in numbers, improved foraging efficiency, energy conservation, and better predator protection.
  • Example: ants, flocks of birds, fish

24 of 25

Example: Schooling Fish

  • Large groups reduce predation
  • Confuses predators
  • Improves survival rate

25 of 25

Recap

  • Organisms respond to environment

​

  • Communication affects behavior

​

  • Behaviors increase survival & reproduction