1) “Nature,” 8 p.m., PBS. Each year, billions of sardines (shown here) make a massive South African run, for … well, no reason that researchers can discern. Along the way, they attract way too many predators; birds, sharks, whales and dolphins sometimes work together for a massive round-up and feast. The result creates visuals that are both gorgeous and bizarre.
2) “Nova,” 9 p.m., PBS. While many scripted shows vanish during the Olympics, this is a strong time for natural history and for David Attenborough, 95. His “Attenborough’s Global Adventure” will continue at 8 p.m. Saturday on BBC America; and here, he views fossils found in his English homeland. They reflect a time when mammoths and humans co-existed.
3) Olympics. NBC has the women’s gold-medal hockey game, live at 11:05 p.m. ET. It cuts its primetime short, (8-10:30 p.m. ET), packing together live coverage (women’s Alpine skiing downhill, women’s halfpipe qualifiers) and tape. There’s more, from 2-5 p.m. on NBC and all day on USA, including live coverage of quarter-finals men’s hockey (8:30 a.m.) and women’s Alpine combined slalom (10:30 p;m.).
4) Lots of games. Most networks are tossing lower-cost shows into their Olympic-time void. ABC follows the ongoing “Jeopardy” college championships (8 p.m.) with two episodes of “The Chase” (9 and 10). Others continue their regular games – “Big Brother: Celebrity Edition” and “The Amazing Race,” 8 and 9 p.m. on CBS; “I Can See Your Voice” and “Next Level Chef,” 8 and 9 p.m. on Fox.
5) Scripted reruns. If you do insist on scripted shows, there are a few. At 8 and 9 p.m., CW has “Legends of Tomorrow” and “Batwoman”; at 10, CBS has “NCIS.” And there’s a new, scripted show, albeit only 10 minutes long: In the whip-smart “State of the Union,” Scott (Brendan Gleeson) is stunned by everything from a non-dairy coffeeshop to a project by his wife (Patricia Clarkson) that he never knew about.