Nudibranch With a Shrimp Partner

Emperor shrimp, and two nudibranches at Dinah’s Beach, Papua New Guinea.
Douglas Good, Pennsylvania
Amidst the bright blue tufts and the dark blue fringes of the beautiful Risbecia tryoni, you might not even notice the red emperor shrimp. The two animals are native to the Indo-Pacific region, and are often found accompanying each other. The nudibranch eats sponges, while it’s shrimp partner (Periclimenes imperator) feeds on worms. Both are small creatures, with the nudibranch reaching 60 millimeters in length, at its smallest.