Apostrophe mistake (An alligators snout) corrected (an alligator's snout)
Fragment (when an alligator's mouth is shut.) corrected (when an alligator's mouth is shut,) *added comma*
Missing word (But with crocodile) corrected (but with a crocodile)
Missing comma (although alligators are dangerous they) corrected (although alligators are dangerous, they)
Verb mistake (although alligators are dangerous they does not) corrected (they do not)
Missing comma (But crocodiles are definitely agressive) corrected (but, crocodiles are definitely aggressive)