[GHS Sophomores Ecology Unit]

How Species Interact With Each Other


One organism kills and eats another to obtain the energy & nutrients it needs.

Predator: The one that kills and eats the other.

Prey: The one that is eaten.

Animal Predators- Cats, dogs, bears, hawks, spiders, etc....

Plant Predators- Venus flytrap, pitcher plant


Competition: A relationship between species in which they attempt to use the same limited resource (same food, water, shelter, etc.).


A. Lion, hyena, & vulture competing for same carcass.

B. Different bird species competing for same nesting space.

C. Frog, toad, spiders, bats, dragonflies compete for same insect food.


Symbiosis: Relationship between 2 different kinds of organisms that live together in some way.

3 Main Types of Symbiosis:

1. Mutualism: Relationship where both creatures benefit.


A. Ants and aphids (ants get honey dew from aphids, aphids get protection.)

B. Rhino & Tick Bird (Rhino gets rid of ticks & fleas , Tick Bird gets free food.)

C. Termite or Cow & Intestinal Beasties: (Termite or Cow gets its plant food digested, Beasties get free food and protection.)

2. Commensalism: Relationship where one creature is helped, the other is neither helped nor hurt.


A. Shark & Remora fish (Shark not helped nor hurt, Remora gets free food, rides, and protection.)

B. Barnacles & Whale (Barnacle gets free ride & food, whale not affected.)

C. Boxer Crab & Sea Anemone: (Crab uses anemone for protection, anemone not affected.)

D. Orchid atop Palm Tree: (Orchid gets to live nearer to sunlight, tree not affected.)

E. Eyebrow mites & People: (Mite gets food & protection, we donŐt even know they are there!)

3. Parasitism: Relationship where one creature is helped, the other is harmed. Host is the creature the parasite lives on & is harming. Parasite is the creature harming the other. Parasites often take food, sap, or blood from the host. Parasites generally weaken the host, but rarely will kill their host.

Examples of Parasites on Animals:

Leech, Tick, Flea, Tapeworm, Liver Fluke, Malaria, Lamprey Eel

Examples of Parasites on Plants:

Dodder, Mistletoe

[GHS Sophomores Ecology Unit]