$hash{$key}= 'ape:b:cat' #stores the values 'ape','b' and 'cat' into the hash using ':' as delimiter
#simple but the delimiter better not be in any values (you would have to escape the delimiter which is messy)

@values= split /:/,$hash{$key}; #get the values out of the string
# checking for a specific value 
if ($hash{$key}=~/(^|:)$whatimlookingfor(:|$)/) {
  print "found it"; 
}

$hash{$key}.= ':' . $anothervalue; #add another value (but if the hash value was empty you have just added two values, an empty string and $anothervalue. This is another disadvantage)

##</code><code>##

$hash{$key}= ['ape','b','cat']; #stores the values 'ape','b' and 'cat' into the hash

@values= @{$hash{$key}}; #get all the values
$value= $hash{$key}->[2]; #get the third value
$value= $hash{$key}[2]; #get the third value, short form

push @{$hash{$key}}, $anothervalue; #add a value