For the third year in a row, the Cal Academy of Sciences hosted a Valentine's party for their African penguin colony.
Members of the public were invited to write Valentine messages on non-toxic cardboard heart-shaped cards for the birds
Biologist Brooke Weinstein said the penguins love the cards for nest-building purposes and welcome the event as a change of pace.
One of the penguins, (generally the male of the bird-couple) will waddle over and take the card out of the biologist's hand, then return to their cave, adding it to the nest. The birds are always working on their nests, and sometimes will even take to retrieving starfish from the bottom of the tank to use as nest-building material.
You can check out the penguins and their Valentines on the Live Penguin Cams here.
Check out the full gallery HERE