Facebook and Instagram announced Monday that the social network will acquire the photo sharing firm in a $1 billion acquisition deal. It is the largest known acquisition in the company’s history — Facebook disclosed in its filing to go public that it spent $68 million on acquisitions between August 2009 and February 2012.

The news prompted quick reaction from Instagram users who worried that Facebook would treat its newest acquisition like other companies it’s acquired in the past. The list includes companies such as Gowalla, Beluga and Snaptu — all of which shut down after being acquired by the social networking giant.

None of those services had quite as many users or as much buzz as Instagram, but all had strong followings of their own. Gowalla, for example, was estimated to have had about 1 million users when it was acquired by Facebook. Now the company’s home page only promises visitors that they’ll be able to download their data there in the near future.

Both Facebook and Instagram were careful to say that the photo-sharing service would still operate somewhat independently, and tried to assure users that there was no need to think that Instagram would follow the same path as the companies that came before it. In fact, in his own note on the deal, Facebook chief executive Mark Zuckerberg struck a fairly humble tone, acknowledging that the popular service has a strong user base and that Facebook has as much to learn from Instagram as the other way around.

Instagram’s success in mobile and on something as core to Facebook’s business model as photos makes the company an attractive purchase, if only to get rid of a competitor.

Michael Scissons, chief executive officer of Syncapse, said he expects Instagram features will be deeply integrated into the new Timeline layout. “It will be a core part of timeline, with strong integration,” he said. “Facebook knows how strong this is to its user system.”

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