What features are characteristic of Actinopterygii?
Actinopterygii are fish that have fins.

Actinopterygii are bony fish that have spiny fins.

For future reference, you might want to add "___" to your question to let people know it's a fill in the blank. You could also add the drop down questions as "A. B. C." to show it's a multiple choice question.

If you make the question easier to understand, you will get more helpful answers = )

i don't know. if i were you, i would search it up online : d