Getting information from models

I have 3 models in my web app. One is for the posts, the remaining models are used to populate the columns in my post model. The POST model has the following columns:

• ID
• Type of animal
• Species

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The other 2 models and their columns are;

TYPE OF ANIMAL:

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• ID
• Name

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SPECIES:

• ID
• Name
• Skin Colour
• Eye colour

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When I create a new object of the POST model, I can choose the names from TYPE OF ANIMAL and SPECIES. Now, in my show view, how can I have access to the other columns of my selected SPECIES model. Lets say I have 10 different species models and I choose number 3, how can I show the information in the skin colour and eye colour columns.