Posted by: sarahegner | October 29, 2013


A unique species has been observed by MarineLab instructors during mangrove snorkels recently, the Caribbean box jellyfish Tripedalia cystophora.  This interesting cnidarian is not a common sight for us so we were intrigued and needed to learn more about the animal.

First off, how bad is the sting?

Always willing to “take one for the team,” various MarineLab instructors tested out the sting for themselves- responses varied from absolutely nothing at all to a mild itch.

Most interesting fact?

They have 24 eyes!  It has been known for well over 100 years that the medusa stage of the cubazoans, box jellyfish, all possess four sensory structures, the rhophalia, each carrying a similar set of six eyes.  There has been much speculation on the usage of these eyes in box jellies but T. cystophora are thought to use their eyes for obstacle avoidance and attraction to light, especially useful in exploiting a unique ecological niche, the mangrove roots.  T. cystophora are able to avoid mangrove branches from damaging their fragile tissue by utilizing vision, as well as their strong swimming ability.  The attraction to light is important because the T. cystophora feed on swarms of the copepod Dioithona oculata which congregate in light shafts created by the mangrove canopy.

Why are we seeing this jelly in Key Largo now and never before?

I have been at MarineLab for over 7 years and have never been lucky enough to see one of these box jellies.  It is thought that with the gradual warming of the oceans, a number of marine species from the Caribbean, such as T. cystophora, have been observed moving into areas of the southern and mid-Atlantic coasts of the United Sates.  Though this was the first sighting by MarineLab staff, the first specimen of T. cystophora was observed in Florida’s waters in 2009.  A single male was discovered in Florida’s Lake Wyman and since then, this jelly has been seen in various areas of southern Florida in greater numbers.

Coates M.M. et al.  (2006)  The spectral sensitivity of the lens eyes of a box jellyfish, Tripedalia cystophora.  The Journal of Ex[perimental Biology 209, 3758-3765

Garm A. et al.  (2007)  Unique structure and optics of the lesser eyes of the box jellyfish Tripedalia cystophora.  Vision Research 48, 1061-1073.

“First report of the box jellyfish Tripekalia cystophora (Cubozoa: Tripedaliidae) in the continental USA, from Lake Wyman, Boca Radon, Florida” by Evan Orellana and Allen Collins.

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