What is a symbiotic relationship? and how does it work?

Are a special type of  interaction between species

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There are 2 main different kinds of symbiotic relationships. 

One being; 
A Obligate symbiotic relationship is when 2 animals can not live without each-other. Meaning, they need each-other, or they can't survive. 

And two being;
They choose to be together, they don't -need- each-other per-say, but they want to be together. 

But in general; its a certain relationship between 2 animals. 

D.) domain, kingdom, phylum, class, order, family, genus, species

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