Hydra vulgaris is one of the evolutionary most ancient animals and has been shown to harbor a multitude of proteins homologous to the programmed cell death or apoptosis regulatory B-cell lymphoma 2 or Bcl-2 family of proteins. Although a small subset of these hydra encoded Bcl-2 proteins have been shown to modulate apoptosis, the molecular and structural basis of apoptosis control remains to be clarified. Here we report affinity measurements of Hy-Bcl-2-4, the sole confirmed pro-survival Bcl-2 protein in H. vulgaris, with BH3 motif peptides of the two confirmed pro-apoptotic Bcl-2 proteins Hy-Bak1 and Hy-BH3-only-X as well as Hy-Bax. We further crystallized Hy-Bcl-2-4 in complex with Hy-Bak1 as well as Hy-Bax. Hy-Bcl-2-4: Hy-Bak1 complex diffracted to 3Å and is under refinement process. Our findings suggest that the Bcl-2 family in Hydra functions in a manner analogous to the Bcl-2 family in humans, and less like in the worm C.elegans or the fruit fly D.melanogaster. Furthermore, our data indicate that substantial differences in the mode of binding exist between Hydra and sponges such as G.cydonium, with Hydra encoded Bcl-2 showing a more promiscuous pro-apoptotic Bcl-2 interaction spectrum compared to its sponge counterpart.