Interdependence in Nature
II. Photosynthesis, Respiration & Interdependence (click here for notes)
III. Relationships in Nature
D. Symbiosis (3 main types)
1. Symbiosis is a relationship where two different species live together in very close contact.
2. There are three main types of symbiotic relationships.
2. There are three main types of symbiotic relationships.
b. Mutualism
In a symbiotic mutualism, the clownfish feeds on small invertebrates which otherwise potentially could harm the sea anemone, and the fecal matter from the clownfish provides nutrients to the sea anemone. The clownfish is additionally protected from predators by the anemone's stinging cells, to which the clownfish is immune.
Cows & Farmers
Ants (Formica glacialis), tending milkweed aphids (Aphis nerii) on common milkweed (Asclepias syriaca)(
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b. Mutualism: 2 or more organisms living closely together both benefit from each other .
i. One of the best examples of mutualism is pollination. Flowers provide nectar as food to the pollinators (such as bees, some bats, birds) while the pollinators move pollen from one plant to the next so that they can make seeds for reproduction. There is a beautiful video of pollination on the page on this website called "Nature's Weird and Wonderful" ii. Another great example of mutualism is the type of seed dispersal where an organism eats the fruit, but poops out the seed. ii. Seed dispersion can be a form of mutualism when the animal eats the seed- bearing fruit and the seed is later pooped out
iii. Some organisms benefit each other AND cannot live without each other. This type of mutualism is called obligate mutualism. 1) Ex. lichen is actually 2 organisms - an algae & a fungus - that cannot live without each other. The algae produces its own food and shares it with the fungus, while the fungus provides a place for the algae to grow and retains water to share with the algae. 2) Darwin's moth (X. morganii praedicta) and Darwin's Orchid (Angraecum sesquipedale) The video above shows how ants harvest honeydew from a different species of aphid than the milkweed aphids we saw. The milkweed aphids are a particular species (Aphis nerii) whose only habitat in the Northern US is the milkweed plant. The only other plant Aphis nerii lives on is the oleander bush, whose habitat is in warmer climate states.
In this form of mutualism, the "farmers" are the ants and the "cows" are the aphids. The milkweed aphids eat the plant and produce a sugary substance called 'honeydew' that the ants 'milk' from the aphid's anus. The ant benefits the aphid by protecting it from predators like ladybugs. Note the tiny 'fly-like' insect at the top of the leaf. It is a tiny parasitic wasp that lays its eggs inside the aphid. The wasp larva grows inside the aphid, eventually killing it. |
E. Decomposition: Detritivores and Decomposers
1. There is no waste in Nature - one organism's waste is another's food or nutrients
2. Decomposers are responsible for consuming dead organic material and returning small molecules to the air and soil a. The molecules (called nutrients) are reused and recycled back into new organisms such as plants. 3. Detritivores are decomposers that eat small bits of dead organic matter a. Ex. snails, worms, fly maggots, insects 4. Decomposers without mouths to eat secrete chemicals called "enzymes" that digest the organic matter and absorb the dead organic matter a. Ex. fungi (including molds), bacteria |
After Life: The Science of Decay
The video below is an excerpt from a documentary entitled, After Life: The Science of Decay. It's a fantastically disgusting and wonderful documentary on the science of "rot". Imagine a world where dead organisms do not decay or decompose. It would just pile up with dead things! This documentary helps you to appreciate how decomposers and detritivores have extremely important jobs and why there really is no waste in Nature.
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F. Scavengers
Scavengers are typically animals that eat other dead animals without having killed them first. The difference between a scavenger and a detritivore is that the scavenger usually eats large quantities of dead meat or plants. What the scavenger leaves behind or the scavenger's waste itself (ex. feces) will then be further broken down by the detritivore or other decomposer, whose waste releases small molecule nutrients into the soil.
It is not uncommon for a predator to also be a scavenger. Meat is meat! |
Test Your Knowledge!
Inter-relationships in Dzanga Sangha
Click on this link to explore the interrelationships among species in Dzanga Sangha National Reserve (located in Central Africa)
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Interdependency Interactive Game
Click on the photo on the left to go to 2 interactive games that test your knowledge about interdependency and relationships in nature. We have talk about many of the species and their relationships that are in these games. A few may be new to you. See if you can figure them out.
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