Creatures with natural reach

[Shade]

If a monster has natural reach, and you are at the edge of its threatened area, can you hit the monster?

For example, an otyugh's tentacles have a natural reach of 15 ft. If Joe the fighter moves up to within 15 ft. of the otyugh, the otyugh can attack Joe. But can Joe attack the otyugh, since its tentacles are "right there"? Or does Joe need to move another 10 ft. to reach the otyught's body.

This came up in a recent session, and three of us were unable to find an answer in the three core rulebooks.

 

[graydoom]

Joe needs to move close enough to get the Otyugh within his reach.
You could (as a house rule) allow the characters to ready an attack to attack the tentacles when the tentacles attacked them, but by the rules you cannot normally attack a creature unless it is within your reach.

Oh, and this should go in D&D Rules.