Lucas was the crusty, unshaven, uncouth captain of the Rita. He was hired by Doctors David Reed and Mark Williams to carry their expedition to Dr. Carl Maia's excavation camp, and later into the Black Lagoon. A rarely serious, happy-go-lucky individual, Lucas knew all the old legends about the upper Amazin, particularly the one about the fabled "man fish," which turned out to really exist in the form of the Gill Man.
Although initially seeming buffoonish, Lucas proved invaluable to the expedition, particularly when he suggested using rotonone to drug and capture the Gill Man. Lucas ended up being one of the only survivors of the party, outliving his doomed crewmen Zee and Chico. He also joined Dr. Maia in coming to the rescue of Dr. Reed and Kay Lawrence, shooting the Gill Man with rifles.
A year later, he returned to the Black Lagoon, this time with a new ship, the Rita II, hired to ferry Joe Hayes and George Johnson of the Ocean Harbor Oceanarium there so that they could capture the Gill Man, although he advised them against doing so. What became of Lucas after this is unknown.
In the 1977 Carl Dreadstone novelization of Creature From the Black Lagoon, Lucas is renamed Jose Goncalves Fonseca de Souza, and is a much more irritable personality. He dies when, after he callously suggests throwing the injured David Reed to the monster, he himself is thrown to the beast instead by Bruno Gebhardt.