Shark Week has been around for 24 years. That’s a long time. Not as long as the millions of years that sharks have existed, but in terms of pop culture, it’s an eternity.

Back in 1987, millions of Americans still didn’t have cable TV. The Fox Network had just been born. “The Cosby Show” reigned supreme in the ratings. The No. 1 song on Aug. 1, 1987, was “Shakedown” by Bob Seger from the soundtrack to “Beverly Hills Cop II,” the biggest movie of a summer that would see the release of “Dirty Dancing,” “RoboCop,” “The Lost Boys,” “Withnail & I,” “The Witches of Eastwick,” “Ishtar” and the truly unforgettable “Ernest Goes to Camp.”

This year, Discovery’s indefatigable series returns with its own Chief Shark Officer, comedian Andy Samberg of “Saturday Night Live” fame. He’s aided by the network’s shark expert Andy Dehart, who actually knows a thing or two about the ancient predators.

Shark Week endures because of (or in spite of) the remarkable sameness of its offerings. How many times can people watch documentaries like “Great White Invasion” (8 p.m.) or “Jaws Comes Home” (9 p.m.)? Apparently, as often as Discovery broadcasts them!

• Shark Week generates a lot of competition. There’s practically a “Whale Week” going on, if you take into account Saturday night’s “Moby Dick” adaptation on Syfy and the Melville-inspired miniseries beginning on Encore on Monday. You knew Animal Planet couldn’t lose its viewers to the sharks, so it dreamed up “Heidi Fleiss: Prostitutes to Parrots” (9 p.m.).

The one-hour special (which probably could have used the word “from” in its title) chronicles the efforts of the former Hollywood madam to stay clean and sober. She’s aided in her effort by more than 20 wild macaws that fill her home with love, music and guano.

• A cop (Rachael Carpani) takes a job with internal affairs, infuriating her family of cops in the new series “Against the Law” (9 p.m., Lifetime).

Today’s other highlights

• Scheduled on “Dateline” (6 p.m., NBC): a look inside congressional deliberations on raising the debt ceiling.

• Regrettable broadcasting decisions abound on “25 Biggest TV Blunders 2” (7 p.m., TV Guide).

• The men open up on “The Bachelorette” (8 p.m., ABC).

• Zen negotiates a kidnapped CEO’s return on “Zen” on “Masterpiece Mystery” (8 p.m., PBS, check local listings).

• A full moon on “True Blood” (8 p.m., HBO).

• The rebels uncover secrets of the aliens’ anatomy, weaponry and social pecking order on “Falling Skies” (9 p.m., TNT).

• A particularly difficult delivery on “In Plain Sight” (9 p.m., USA).

• Buried with snakes on “The Glades” (9 p.m., A&E).

• Events spiral out of bounds on “Breaking Bad” (9 p.m., AMC).

• Jeff’s dinner party avoidance scheme backfires on “Curb Your Enthusiasm” (9 p.m., HBO).

• Drama appears in a TV remake of Vince’s movie on “Entourage” (9:30 p.m., HBO).