Instagram has announced that it reached a whopping 80 million users who shared a total of more than 4 billion photos, even as it rolled out a new update. One feature, however, is noticeably missing after the update: the "Find Your Friends" on Twitter feature, which allowed users to follow on Instagram the same people they follow on Twitter.

Instead of that feature, the update leaves users with just a message: "Unable to Find Friends. Twitter no longer allows its users to access this information in Instagram via the Twitter API. We apologize for any inconvenience."

Twitter apparently has turned off its API from Instagram, but other social apps such as Foursquare and The Fancy still have access, which is a bit curious. There are several possible theories for this seemingly random decision (though it's most likely not random at all). One reason behind this change could be the photo sharing app's sheer size, with an impressive 80 million users. Another likely scenario is that Twitter is trying to ramp up competition, seeing as Instagram is now owned by social networking giant Facebook (The Wall Street Journal reported earlier this year that the micro-blogging site tried to buy Instagram before Facebook). Also possible, and perhaps more realistic, is that Twitter simply wanted to have more control over user experience on its platform.

"We understand that there's great value associated with Twitter's follow graph data, and we can confirm that it is no longer available within Instagram," a Twitter spokesperson told CNET. It's the "great value" part that suggests Twitter wants Instagram to pay, if it doesn't already, or pay more, if it does, for the use of its API.

Twitter opted for a similar approach just last month with LinkedIn, when it nixed the feature that allowed LinkedIn users to publish tweets to their profiles. Users can still push LinkedIn updates to Twitter, but not the other way around. The same scenario unfolds now with Instagram - users can no longer find Twitter friends through the app, but Instagram's "Tweet Photo" feature is still available, which means Twitter did not revoke the entire API from Instagram, but only the portion allowing users to search for friends.