1) “Secrets of the Octopus,” 8-10:52 p.m., National Geographic Channel. Ignored (or feared) for centuries, octopuses (shown here) are the new media stars. They deserve the attention. They can change color, shape and image; they can hide from a predator, befuddle a prey, befriend a scientist. This terrific three-parter reruns at 10:52 p.m. today and then at 7:08 p.m. Monday, in an Earth Day marathon.
2) Nature show reruns. On the eve of Earth Day, BBC America reruns part of its splendid “Planet Earth: The Blue Planet.” That’s from 9 a.m. to 12:30 p.m.; at 4 p.m., National Geographic focuses on elephants – a scene from the “Great Migrations” series and then (from 4:13 to 8 p.m.), the full “Secrets of the Elephants.”
3) “The Equalizer,” 8 p.m., CBS. After a slow stretch – with only two new episodes in six weeks – this is ready to close the seasoin with five straight new ones. Tonight, a former Chinese agent has been poisoned and comes to Robyn for help. That’s followed by new hours of “Tracker” and “CSI: Vegas.”
4) “Alice & Jack” finale, 10 p.m., PBS. With subtlety and depth, two gifted actors have offered the complicated relationship of two near-opposite people. Tonight starts with a flashback to the minutes before Alice (Andrea Riseborough) met Jack (Domhnall Gleeson). Then we return to the bittersweet finish.
5) ALSO: From 7-10 p.m., CW has “Point Break” (1991), which manages to blend crime, surfing, Patrick Swayze and Keanu Reeves. From 8-10, ABC’s “American Idol” has contestants do songs from people in the Rock & Roll Hall of Fame. Also, PBS has a warm “Call the Midwife” at 8 p.m., with brothers left at a church; at 9, “Mr. Bates vs. the Post Office” sets up next week’s triumphant finish.
— Mike Hughes, TV America