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Learn how animals compete for resources and how predators and prey interact.
Imagine you are at a party with 20 friends, but there is only one pizza. Who gets to eat? In nature, this 'pizza problem' happens every single day!
In every ecosystem, resources like food, water, and living space are limited. This means there isn't always enough for everyone. When two or more organisms try to use the same resource at the same time, we call this competition. Think of it like a game of musical chairs; when the music stops, not everyone gets a seat. Animals don't just compete with other species; they often compete with members of their own family! To survive, an animal must be better at finding water or defending its territory than its neighbors.
Quick Check
What are the three main resources that animals usually compete for?
Answer
Food, water, and space (or territory).
1. A cheetah spots a gazelle from a distance using its incredible eyesight. 2. It uses its physical adaptation (specialized leg muscles and a long tail for balance) to accelerate to 70 mph. 3. It uses a behavioral adaptation by creeping close through tall grass before sprinting to save energy.
The animal that is hunted is called the prey. Just like predators, prey have evolved amazing ways to avoid being eaten. Some use camouflage to blend into their surroundings, like a leaf insect that looks exactly like a green leaf. Others use mimicry, where a harmless animal looks like a dangerous one to scare predators away. Some prey find safety in numbers, forming large herds or schools of fish to confuse a lone hunter. If a prey animal survives long enough to have babies, it passes these winning traits down to the next generation.
Quick Check
Is a zebra's stripes an example of a physical or behavioral adaptation?
Answer
Physical adaptation (it is a part of their body that helps them blend into the herd to confuse predators).
Predators and prey are locked in a never-ending cycle that keeps nature in balance. This is often called a population cycle. If the number of prey increases, there is more food for predators, so the predator population grows. However, as more predators eat the prey, the prey population starts to drop. With less food available, the predator population eventually drops too. This prevents any one species from taking over the entire ecosystem. It is a natural check-and-balance system that has worked for millions of years.
In the Canadian forest, the Lynx (predator) and the Snowshoe Hare (prey) show a perfect cycle: 1. When Hare populations are high, Lynx have many babies. 2. The large Lynx population eats many Hares, causing the Hare population to crash. 3. Because there are fewer Hares, the Lynx begin to starve, and their population drops. 4. With fewer Lynx hunting them, the surviving Hares reproduce quickly, and the cycle starts over roughly every 10 years.
Which of the following is a behavioral adaptation?
If the prey population in an area suddenly decreases, what will likely happen to the predator population?
Competition only happens between different species, never between animals of the same species.
Review Tomorrow
In 24 hours, try to explain to a friend how a 'population cycle' works using the Lynx and the Hare as an example.
Practice Activity
Go outside or look out a window. Identify one animal (like a bird or squirrel) and list one physical adaptation it has for finding food or staying safe.