Name_____________________________________________Period_____Date_______________
SYMBIOSIS
Scenario #1: There is a caterpillar called the tomato hornworm. A female wasp lays tiny eggs on the back of the
caterpillar. The eggs then hatch and the young wasps burrow themselves into the caterpillar and slowly eat it alive. After
the wasps reach adulthood the catapillar will die or has already died.
1. Is this relationship between the caterpillar and wasp one of mutualism, commensalism, or parasitism? Why?
Parasitism: Win – Lose; the wasps win because they have a food source;
the caterpillar loses because it gets eaten!
2. What would happen if the caterpillar had a way of taking the young eggs off his
back?
The wasps would have to look for another source of food – another place to lay its
eggs
3. Why would this be a bad development for the wasp if the caterpillar figured out a
way to take the eggs off his back?
The wasp population would decrease until they find another way for the young wasps to feed themselves!
Scenario #2: The Egyptian Plover bird is well known for eating parasites that feed on crocodiles. The crocodile openly
invites the bird to hunt on its body, even going so far as to open its jaws to allow the bird to enter the mouth safely to
hunt the leeches from its gums. For the bird, this relationship not only is a ready source of food, but a safe one
considering that few predators would dare strike at the bird when it is so close to a crocodile.
4. Is this relationship between the crocodile and bird one of mutualism, commensalism,
or parasitism? Why?
Mutualism: Win – Win; the bird gets food and protections; the crocodile gets a dental
cleaning!
5. What would happen if the crocodile ate the bird?
The bird would stop hanging around the crocodile’s mouth; they would need to find
another source of food; they would need to develop a predator warning system
6. Why would eating the bird be a bad idea for the crocodile?
Food and parasites in the teeth could lead to disease and lose of teeth for the crocodile!
Scenario #3: Every human has microscopic organisms that live inside his intestine. The organism hooks onto your
intestine wall and feeds off the food going through your intestines. These organisms are brought into your digestive
track through the food you eat. These organisms produce nutrients and vitamins humans need to survive.
7. Is this relationship one of mutualism, commensalisms, or parasitism? Why?
Mutualism: Win-Win; humans are provided nutrients and vitamins from the organisms; the organisms are
Provided food
8. What would happen if the human stopped eating food?
The organisms die; the nutrients are no longer provided to humans – lose-lose!
9. What would happen if there were too many of these organisms in your intestine?
Too many organisms would reduce food nutrients to humans causing an unbalanced system which usually means
sickness or malnutrition
Scenario #4: There is a fungus known as tenia pedis or athlete’s foot. It is a fungus that commonly starts on the feet of a
human. The fungus feeds off the sweat of the humans while humans are left with
ichy and cracked skin.
10. Is this relationship between the athlete’s foot and the human one of mutualism,
commensalism, or parasitism? Why?
Parasitism: Win – Lose; the fungus wins by having a “free” food source; the human
loses by getting eaten/experiencing itching and discomfort
11. What would happen to the human if the tenia pedis died?
The human would be HAPPY – no more itching or cracked sore skin.
12. Is it in the human’s best interest if the tenia pedis died?
YES!!!
Scenario #5:
There is a shark that lives off the California coast. The shark spends much of his time in the water hunting and eating
food. A small fish called a remora hooks onto the sharks belly and eats the leftovers of the sharks meal. The shark is
unaffected by the remoras presence while the fish rides happily and eats freely on the belly of the shark.
13. Is this relationship between the shark and fish one of mutualism, commensalism,
or parasitism? Why?
Commensalism: Win – doesn’t care; the shark doesn’t care about the remora
hanging around; the remora gets free food and transportation.
14. What would happen if the shark became bothered by the fish riding on his belly,
what type of relationship would it become? (mutualism, commensalism, or
parasitism)
It would be come mutualism – the shark would be “harmed” by the relationship
15. Why would bothering the shark be a bad idea for the fish?
The remora would lose its source of food and transportation.