Why is it "natte" here?
Susande, is it possible to post the link as text? My phone can't open the hyperlink (who knows why) and this adjective ending has been getting me over and over!
That's the Grammar Overview, just scroll down all the way up to 'Adjectives'.
Come on guys, not hard to let us follow hyperlinks....
Is the word "turtle" feminine?
No, it's common gender (which includes feminine and masculine), thus, it takes de as a definite article.
Neuter gender nouns, in the other hand, take het as a definite article.
Note that grammatical gender is not related to biological gender.