Since Bob Marley and his Jamaican brethren introduced reggae music in America, the pop genre has taken firm root here. Like any form of pop music, reggae is highly flexible, and with the passing of Marley, a new constellation of reggae forms and personalities is emerging.

Mutabaruka, who performed at a packed 9:30 club last night on a bill with local reggae band Mighty Invaders, is an example of a new reggae mutation. A published poet in Jamaica, who appeared at the 1982 Reggae Sunsplash Festival, Mutabaruka performs his polemical poetry over the fluid reggae beat.

As a performer, Mutabaruka was hypnotic, jerking and weaving as if possessed, fists raised, shackled, with a long silver chain, his hair plaited in reggae's trademark dreadlocks. Although at times it was difficult to understand his Jamaican dialect, the music's repetitiveness made it clear that Mutabaruka's danceable diatribes addressed such universal themes as industry, imperialism, apartheid and the sexes.

"Your body is for the music, and your soul is for the words," Mutabaruka said, and the audience seemed to listen and move. If they chose not to spend the effort required to distill Mutabaruka's message, they could dance to the kinetic rhythms of his voice--a percussion instrument in itself.