“The Academy” (8 p.m., MNTV): The blistering training regimen endured by would-be L.A.

“The Academy” (8 p.m., MNTV): The blistering training regimen endured by would-be L.A. sheriff’s deputies is traced in this series.

“Secrets of the Crocodile” (8 p.m., Animal Planet): A year after Steve Irwin’s death, Animal Planet is airing a weeklong celebration of the exuberant “Crocodile Hunter” whose forays among wildlife were a staple of the channel. Irwin, who died in September 2006 at 44 when his heart was pierced by a stingray, is featured in new and previously aired specials that recount his work and showmanship that carried a conservation message. “Secrets of the Crocodile,” debuting 8 p.m. tonight, is the centerpiece. The program details Irwin’s final crocodile research expedition to illuminate the reptiles that have scarcely changed in their thousands of years on Earth.

“Dale” (8 p.m., CMT): The biographical tale of the racer Dale Earnhardt puts a spin on his full-throttled life.

“Jail” (8 p.m., MyNetworkTV): Maybe it’s not exactly what Paris or Nicole endured, but “Jail” promises to give a firsthand view of what some experience from booking to their first moments behind bars. The series, from “COPS” creator John Langley, uses that long-running show’s network-described “video verite” style to let viewers peek inside the slammer. It’s sad, it’s funny, it’s scary, viewers are promised, to discover what happens to “casual offenders and hardened criminals once the sheriff throws away the key.” “Jail” visits facilities in cities including Las Vegas; Tampa, Fla.; Cincinnati; Portland, Ore., and Fort Worth, Texas.

“Lincoln Heights” (8 p.m., ABC Family): “Lincoln Heights,” the rare TV drama that makes a black family its focus, returns for its second season. Dad Eddie Sutton (Russell Hornsby), a lawman, has been injured in the line of duty and finds himself playing househusband to the hilt, cooking and setting down new rules for the kids. Mom Jenn (Nicki Micheaux) leaves the hospital to work in a local clinic, an adjustment that has to be balanced with her home life. As children will, the Sutton offspring are living their own lives: Cassie’s (Erica Hubbard) romantic life heats up when she meets an artist and preteens Tay (Mishon Ratliff) and Lizzie (Rhyon Brown) are experiencing their own brushes with young love.

“The Biggest Loser: Reunion” (9 p.m., NBC): Did they pack the pounds back on after the cameras went away? Thirteen contestants from the show’s past three seasons reunite for a one-hour special to see who’s still svelte and who’s struggling with the scale. The contestants talk about their personal lives and the physical and emotional changes they’ve experienced. Alison Sweeney, who replaces Caroline Rhea, hosts. The series begins its fourth season on Tuesday, Sept. 11, at 8 p.m.