Biology
Symbiosis and relationships
How living things share their lives: sometimes helping each other, sometimes taking advantage, sometimes competing for the same food.
No living thing lives entirely on its own. In every habitat animals, plants, and fungi meet and form relationships with one another. Some relationships benefit both sides, others harm one side. These relationships help decide who survives in a habitat.
Mutualism: both win
In mutualism both partners gain an advantage. A bee collects nectar from a flower and carries pollen to the next flower along the way. The bee gets food, the plant gets pollinated and can form seeds. Both sides benefit, which is why such a relationship is also called a symbiosis in everyday language. A lichen goes even further: there a fungus and an alga live together as one single body. The alga makes sugar in the sunlight, the fungus supplies grip, water, and . That is how lichens grow even on bare rock, where neither of them would survive alone.
Eats: nothing, it is a producer
Eaten by: Hare, Mouse, Beetle
If it disappears: Without grass all herbivores lose their food and the whole web collapses.
Parasitism: one takes advantage
In parasitism only one side has an advantage while the other has a disadvantage. A tick sucks blood from a deer and feeds on it. The deer loses blood and can even become ill. The parasite lives at the host's expense, but usually does not kill it right away, because it still needs the host. That is exactly what sets a parasite apart from a predator: a parasite is much smaller than its host and taps it over a long stretch of time, while a predator kills its prey and eats it up.
Competition for the same resources
Often two species need the same thing: the same food, the same nesting site, or the same water hole. Such scarce goods are called resources, and when two species struggle over them, they are in competition. Two bird species that both eat the same berries have to share the limited supply. Whichever is better suited to the habitat finds more of them and raises more young in the end.
Predator and prey
A predator hunts and eats other animals, the prey. A fox hunts mice, an owl hunts voles. When there are many mice, the predators find food easily and grow in number. When the predators become too many, the number of mice falls again. In this way predators and prey keep each other in check.
Exercises
0 of 6 solvedTime to try it yourself. You can't break anything, every attempt counts.
In which relationship do both partners have an advantage?
A tick sucks blood from a deer. Which relationship is that?
Mutualism, parasitism, competition, and the predator-prey relationship: how many kinds of relationship does the text describe in total?
Match each relationship to the example that fits.
A fox eats 3 mice a day. How many mice does it eat in 4 days?
When two species need the same food and have to share it, this is called ….