Stingrays..."Clean the site of the puncture wound and remove the barb if possible"
Nothing could be further from the truth. If you are hit by a stingray (and shuffling your feet is how to avoid being hit by one...stepping on one is how you are hit) and the barb remains in the wound do not attempt to remove it. A stingray's barb has hundreds of backwards serrations along the edges (it looks like a dagger) and to try and pull it out will not only bring excruciating pain but will also do more damage to you.
Go straight to a hospital if you are hit by a stingray and let them treat the wound including removal of the barb if it is still embedded.