use Data::Dumper;
my @bigarray = (
    [ "123*jeff", "tortoise", "qwerty" ],
    [ "456*john", "parrot", "azerty" ],
    [ "789*jane", "budgie", "abcdef" ],
    );
print Dumper \@bigarray;  # before
...
print Dumper \@bigarray;  # after

##</code><code>##

splice @$_, 0, 1, split /\*/, $_->[0] for @bigarray;

##</code><code>##

foreach my $arr ( @bigarray ){
  my $item = shift @$arr;
  unshift @$arr, split /\*/, $item;
}