Smooth fan lobsters (Ibacus novemdentatus) really know how to live life the easy way in their youth. As larvae, these lobsters travel the ocean by latching on to Moon jellyfish and even eat the jellyfish as they ride! To fight back, the jellyfish will try to cover the larvae in infectious mucus that can cause a potentially fatal bacterial infection. Not to be outdone, the larvae are able to groom this mucus off of themselves before getting sick. Since the larvae are covered in scales, the jellyfish cannot sting the outside of the lobster; however, the larvae are vulnerable on the inside of their gut. Therefore, if the lobsters want to eat the jellyfish’s tentacles which contain venomous tubules (and indeed they do want to eat them), they have to neutralize the toxin in some way. In a truly remarkable display of an evolutionary arms race, the larvae have the ability to wrap the stinging cells of the tentacles in a protective coating that keeps them from activating during digestion.

Sketch by Victoria Farrar. Fact by Adrian Perez.

Sources:

Kamio, M., Wakabayashi, K., Nagai, H. and Tanaka, Y., 2016. Phyllosomas of smooth fan lobsters (Ibacus novemdentatus) encase jellyfish cnidae in peritrophic membranes in their feces. Plankton and Benthos Research, 11(3), pp.100-104.

Kamio, M., Furukawa, D., Wakabayashi, K., Hiei, K., Yano, H., Sato, H., Yoshie-Stark, Y., Akiba, T. and Tanaka, Y., 2015. Grooming behavior by elongated third maxillipeds of phyllosoma larvae of the smooth fan lobster riding on jellyfishes. Journal of Experimental Marine Biology and Ecology, 463, pp.115-124.