  We study open strings on giant gravitons (D-branes on cycles) in the
ABJM/$AdS_4\times \mathbb{CP}^3$ correspondence. We find that their energy
spectrum has the same form as the one for closed strings, with a nontrivial
function of the coupling, avoiding BMN scaling. A similar, Cuntz oscillator,
Hamiltonian description for the string (operators at strong coupling) to the
$AdS_5$ case is valid also in this case.
