In order to find out which perl is installed you can run
This is perl 5, version 16, subversion 3 (v5.16.3) built for x86_64-linux-thread-multi
On most of the FreeBSD servers there is perl5.16.x and perl5. /usr/bin/perl is 5.16.3 /usr/bin/perl5 is 5.005_03 - most likely you want the later version of perl. The older version is part of the FreeBSD operating system itself and is deprecated.
You can call perl5.16.x as perl e.g.
perl -v This is perl, v5.16.3 built for i386-freebsd-64int
You can call the older perl5 as perl5 e.g.
perl5 -v This is perl, version 5.005_03 built for i386-freebsd