How long to Warlock Invocations last?

[Greenfield]

I D&D 3.5, Warlocks get a number of Invocations, which are spell like abilities, that they can apparently use as often as they like.

Some of these resemble specific spells, others don't.

One, for example, mimics the effects of the Black Tentacles spell, but includes additional 2D6 of cold damage to all in the area.

How long do effects like that last? The description implies a duration to match the spell, but I want to be sure.

 

[Jackinthegreen]

Based on the text for spell-like abilities I'd say that we're supposed to use the duration for the spell but with the warlock's own caster level. Of particular note is the first line: "Usually, a spell-like ability works just like the spell of that name. A few spell-like abilities are unique; these are explained in the text where they are described."