The "shebang" line in a perl script is not perl, but instead a shell directive. It tells your shell to pipe the contents of this file to this executable when this script is executed. #! is just the syntax that is required to indicate this.
Alternatively you could pipe the contents to python or any other binary. Also your perl script doesn't have to end in .pl. It just makes it easier for us to know what it is when so named.
Unless of course you're in a windows environment, in which case the shebang is ignored and the file is executed based off of filetype associations, in which case the .pl is important.