Octaman [1971 - Mexico, USA] mutant sci fi horror

A scientific expedition to a remote Mexican fishing community, led by Dr. Rick Torres and Susan Lowry, discovers unhealthy amounts of radiation in the local waters. They find a small mutant octopus that can crawl on land. While away searching for more funding, a humanoid octopus, Octaman, attacks the camp and slaughters the remaining crew. Octaman continues to harass the camp, killing other team members and snatching Susan. Using flashlights to blind him momentarily, he releases Susan. They subdue him inside a ring of fire so that a net can be thrown over him. But a morning rain revives him and he escapes. He is eventually tracked into a cave, but Octaman chases them into a dead end tunnel and creates a rock slide that traps the scientific team for a while. When they return to their RV, Octaman is hiding inside.