An active ingredient comprising a synergistic mixture of soluble collagen from cnidarians and extract of zooplankton, a cosmetic composition containing same, and a cosmetic care method comprising the topical application of said composition.Agent actif comprenant un mélange synergique de collagène soluble issu de cnidaires et dextrait de zooplancton, composition cosmétique les contenant et procédé de soin cosmétique comprenant lapplication topique de ladite composition.