Octopus like to be left alone; they are often bothered by scuba divers.

Please check your attempt to pluralize octopus. Your first sentence is also in need of a semicolon, but it is uninteresting and incomplete. How smart is a cat? You need to further expand it.

You’ve got misspellings in your second sentence.

Most divers aren’t afraid of octopuses, in fact, divers enjoy meeting them.

Octopuses like to be left alone. They are often bothered my scuba divers

Most divers aren’t afraid of octopuses; in fact, divers enjoy meeting them.

(You could also use . instead of ; if you prefer.)

Octopuses like to be left alone, but they are often bothered by scuba divers.