IB MYP Integrated Science- Biology - Predator/prey-Study Notes - New Syllabus

Predator-Prey

🌟 Introduction

A predator-prey relationship is an interaction where one organism (predator) hunts, kills, and eats another organism (prey). This interaction maintains ecosystem balance, controls population size, and ensures smooth energy flow through food chains.

🐾 What Is a Predator?

• An organism that hunts, kills, and consumes other organisms.
• Usually equipped with special adaptations for capturing prey.

Common Predator Adaptations

• Sharp teeth and claws
• Speed and agility
• Highly developed eyesight or smell
• Camouflage for stealth
• Venom in some species

Examples: Lion, tiger, eagle, snake, spider

🐰 What Is Prey?

• Organisms that are hunted and eaten by predators.
• Develop adaptations to avoid being captured.

Common Prey Adaptations

• Speed (deer, rabbits)
• Camouflage (insects, reptiles)
• Living in groups (schools, herds)
• Defensive behavior (alarm calls)
• Mimicry

Examples: Deer, zebras, insects, fish

🔁 Predator-Prey Cycle

A classic predator-prey relationship shows linked population cycles:

• Prey increase → predators increase (more food available)
• Predators increase → prey decrease (higher predation)
• Prey decrease → predator numbers fall (less food)
• Predators fall → prey recover

This cycle repeats, maintaining long term balance.

🔬 Importance of Predator-Prey Relationships

Maintain Population Balance

• Stops overpopulation of any species
• Prevents resource depletion

Promote Natural Selection

• Predators catch weaker, slower individuals first
• Prey evolve better survival traits
• Leads to an “evolutionary arms race”

Improve Ecosystem Health

• Controls herbivore numbers
• Maintains biodiversity
• Influences distribution of organisms

🧩 Examples of Predator-Prey Interactions

• Lynx and Snowshoe Hare: Hare increase → lynx increase; hare drop → lynx drop
• Frogs and Insects: Frogs control insects; insects rebound if frog numbers fall
• Wolves and Deer: Wolves prevent overgrazing; vegetation improves when wolves are present

🛡️ Adaptations: Predator vs Prey

🌿 Human Impact on Predator-Prey Systems

• Habitat destruction disrupts natural balance
• Hunting reduces predator numbers
• Invasive species change food chains
• Removing predators leads to prey overpopulation
• Conservation efforts help restore equilibrium

📊 Summary Table

⚡ Quick Recap
Predator → hunter
Prey → hunted
Both develop special adaptations to survive.
Their numbers follow a linked population cycle.
Crucial for ecosystem stability and biodiversity.
Human activities can easily disturb this balance.