SANTA CLARA — The 49ers have fallen from the unbeaten ranks, and escorting their 29-3 loss Sunday night in Seattle was a troubling trend: penalties.

Overall, the 49ers are the second-most penalized team in the league: 25 penalties for 206 yards. Only the winless Tampa Bay Buccaneers have more (26 penalties, 220 yards).

At Seattle, the 49ers got penalized 12 times for 121 yards, the highest total since coach Jim Harbaugh's 2011 arrival. The record-setting crowd noise couldn't be blamed for all the 49ers' mishaps, as they had two false starts and one delay-of-game call.

No, the 49ers struggled in several areas before losing their cool down the stretch. That effort came in the wake of their 11 penalties for 85 yards in a season-opening win over Green Bay.

Colin Kaepernick #7 of the San Francisco 49ers looks on as Richard Sherman #25 and D’Anthony Smith #94 of the Seattle Seahawks celebrate a saftey
Colin Kaepernick #7 of the San Francisco 49ers looks on as Richard Sherman #25 and D'Anthony Smith #94 of the Seattle Seahawks celebrate a saftey during their game at Qwest Field on September 15, 2013 in Seattle, Washington. (Photo by Jonathan Ferrey/Getty Images)

Linebacker Patrick Willis demanded after Sunday's game that his teammates — not coaches -- take accountability for this yellow-flag barrage.

"You're going to have some (penalties) for fanatical efforts, but some can be prevented and we need to take ownership of them," Willis said.

Tight end Vernon Davis offered a stark assessment, too.

"If any team continues to stock up the penalties, just penalty after penalty, it can cost you the season if you do it every game," Davis said. "But we're not going to allow that to happen. We're better than that. It was just a game where we just acted instead of thinking."

Here is a penalty-by-penalty description of Sunday's infractions:

1. False start, Anquan Boldin (5 yards): This third-series snafu resulted in a second-and-11 situation and eventual punt.

2. Delay of game, Colin Kepernick (5 yards): One play after Boldin's error, the 49ers failed to get the snap off in time on third-and-11. Surprisingly, this was their only delay-of-game call all night.

3. Pass interference, Carlos Rogers (7 yards): Russell Wilson was 0-of-5 when he started the Seahawks' third series with a short pass to Sidney Rice when Rogers interfered.

4. Holding, Bruce Miller (4 yards): Miller tackled Malcolm Smith to the ground in the end zone to result in a safety and a 2-0 deficit.

5. Holding, Tramaine Brock (0 yards): Called for three special-teams penalties last week, Brock committed a hold on a second-quarter punt return that ended the first half.

6. Face mask, Ahmad Brooks (10 yards): Russell Wilson had conceded an 8-yard sack when Brooks' hand met Wilson's facemask. "I didn't mean it," Brooks said afterward.

7. False start, Mike Iupati (5 yards): Two snaps after getting plowed over, Iupati committed a false start. The 49ers have six false-start penalties through two games.

8. Pass interference, Nnamdi Asomugha (40 yards): Asomugha ran with Golden Tate down the right sideline without looking back for the football before it was too late.

9. Unnecessary roughness, Aldon Smith (14 yards): The 49ers' frustrations became evident by this point, when Smith slapped a Seahawks helmet after a 15-yard completion. Smith, who had two sacks, tackled Wilson for a 3-yard loss on the next play.

10. Unsportsmanlike conduct, Vance McDonald (15 yards): The rookie tight end lost his cool and shoved linebacker K.J. Wright after a fourth-quarter play.

11. Holding, Perrish Cox (10 yards): Trailing by 19 points with 5:13 left, Cox held on a punt return and the 49ers' final series started at their 13-yard line.

12. Unnecessary roughness, Anthony Davis (6 yards): Davis capped off the line's miserable night with a shove that he tried justifying later on Twitter: "The penalty. In physical combat/Oline play it's human nature to fight or flight when your backs against the wall. Never flight. Sue me."

Asked if the 49ers lost their composure, Harbaugh said: "We definitely made things harder on ourselves, yes."