Unit 1 Chapter 2 Living and Non-Living Things Interact in Ecosystems Section 2.1 – Types of Interactions
Symbiosis • Symbiosis: • A biological interaction in which two species live closely together over time in a relationship where at least one of the species benefits.
Symbiosis (cont.) Can you think of an example of symbiosis. (Note: it’s important to remember that symbiosis does not usually lead to the death of either organism in the relationship) EX:
Symbiosis (cont.) • We will study three types of symbiotic relationships. • (your example from the previous slide should fit into one of the categories) • Parasitism • Mutualism • Commensalism
Parasitism Parasitism is a symbiotic relationship between two species in which one benefits and the other is harmed. • The organism that benefits by obtaining food is called the parasite. • The organism which is harmed and provides food for the parasite is the host Ticks and Tapeworms Pictured on the right are examples of parasites. Q: Why wouldn’t parasites want to kill their host?
Parasitism A Parasite for Sore Eyes The parasitic flatworm causing discomfort for the snail on the right feeds on birds. However, the eggs are found in the birds droppings. When the snail eats the droppings ( I know it sounds gross), the larvae hatch and move to the snails eye stem where they cause a swelling which looks like a caterpillar to bird passerby's. The birds eat the snail allowing the parasite to be passed to the bird, and the cycle continues. Within the video section of National Geographic’s website, do a search for “Snail Zombies” to learn more about this.
Parasitism in Newfoundland • Brain Worm in Caribou • Many woodland caribou on the Avalon Peninsula of Newfoundland were found dead, or weak and staggering. The cause was a large number of parasitic roundworms found in their lungs and brains • Dwarf Mistletoe (Newfoundland’s smallest flower ) • It attaches itself to trees and grows root-like structures into the host to extract nourishment
Predator Prey Relationships are not Parasitic… While it is tempting to suggest predator-prey relationships as examples of parasitism, these are not parasitic relationships. Why is it important that Parasites not kill their hosts? The parasite’s purpose is not to kill the host as it will then destroy its energy source.
Mutualism Mutualism is a type of symbiosis, in which both partners benefit. Have you ever seen lichens similar to those shown on the right growing on rocks. These lichens represent a mutual relationship between a fungus and an algae. The Fungus (outside layers) provide protection against drying while the photosynthetic algae (inner )provide food
Mutualism in Newfoundland Bumble Bees like the one pictured here represent a mutual relationship between the bee and the flower. The bumble bee obtains nectar from the flower to feed it’s larvae. Do you know what benefit the flower receives?
Commensalism Commensalismis a symbiotic relationship, in which one partner benefits and the other appears neither to lose nor gain from the relationship. The Barnacles growing on the whale shown here provide no benefit or harm to the whale while they obtain a secure lifelong home and a source of mobility. (c) McGraw Hill Ryerson 2007
Commensalism Can you think of another example of commensalism?
Questions • Chapter 2 Assignment Questions • Page 39…..3, 4, 7 • Q: Research and describe an example of parasitism, mutualism, and commensalism that has NOT been discussed in class.