Grab Penalties for Trex, Crocodiles, Snakes etc.

[ptlans]

Do the creatures mentioned in the subject line actually take the -20 penalty to CMB checks if they only use their mouths to make & maintain the grapple?

It makes no sense to me whatsoever that a croc or t-rex would have a tough time holding onto something with their jaws. Most creatures with only a bite attack or no limbs (snakes) have some kind of feature, typically strong jaws and or teeth that are angled inward, that allow them to hold onto their prey.

Is there some kind of exception for creatures like this? Or do I have to go with it as a house-rule that certain creatures are exempt from the -20 penalty while using grab with only one body part?

[blahpers]

Yes, they take the penalty. If a creature does not want to take the penalty, they can grapple with their entire body as normal.

You're right about the special grapple-friendly features, though--that's why those creatures have grab at all.

[Nefreet]

The -20 penalty is only if you don't want the grappled condition yourself.

[TheJrade]

Makes perfect sense. After all, remember how clumsy the T-Rex was after he gobbled the lawyer off the toilet?

[Matthew Downie]

A T-Rex gets +32 to 'grab', or +12 to 'hold'.

If if uses 'grab', then it suffers the penalties of the grappled condition because it's making use of its whole body. This makes sense if you imagine a T-Rex grappling a Triceratops with its mouth. It needs its legs and tail (and maybe even its tiny little hands) for leverage, so would have a hard time defending itself while doing so.

When a T-Rex wants to eat a lawyer (which paleontologists now believe comprised a relatively small proportion of their diet) it can use the 'hold' option to just sweep him up (most lawyers have a CMD of 14 or less) without sacrificing its ability to defend against velociraptors.

If you're going to house-rule for realism, you should start by taking away their ability to swallow the triceratops whole.