Not so. They get longer than that. A quote from a Yahoo news article:angellous_evangellous said:Buttercup, that one is a fossil - http://tellmewhereonearth.com/Web%20Pages/Fossils/Fossils_Page_3.htm (near the bottom of the page). That one is from a prehistoric stingray!
The longest ones today seem to be about three inches.
"Marine experts say stingrays can deliver horrific, agonizing injuries from the toxin-laden barbs, which can measure up to 20 cm (8 in) in length and cause injuries like a knife or bayonet"
You can read the rest of it here http://news.yahoo.com/s/nm/20060905/people_nm/australia_irwin_dc_12
Steve had pulled the barb out of his chest and then he died. The stingray that stung him was about 220 pounds.