Synalpheus regalis is a
species of
snapping shrimp that commonly live in
sponges in the
coral reefs along the tropical West Atlantic. They form a prominent component of the diverse marine
cryptofauna of the region. For the span of their entire lives, they live in the internal canals of the host sponge, using it as a food resource and shelter. It has been shown that colonies contain over 300 individuals, but only one reproductive female. Also, larger colony members, most of which apparently never breed, defend the colony against
heterospecific intruders. This evidence points towards the first case of
eusociality in a marine animal.