Cephalopodcast

Mesoglea (tissue) from a sea jelly, © Jason Robertshaw

What the Shell Is That? is my series on beachcombing and tidal life. Living on the west coast of Florida, it is mostly about shells, but can also be about other flotsam, fauna and even flora.

Note: I spent a lot of the last week traveling, so did not get a chance to hit the sand. So this is a WSIT encounter from a couple of months ago.

Sea Jelly Mesoglea

Date: 1 December 2007
Location: Siesta Key, Sarasota, Florida, U.S.A.
All along the surf.

Report:
Back around Thanksgiving of last year there were reports of increased numbers of sea jellies in Sarasota Bay. On several occasions I witnessed New Pass awash with numerous drifting moon jellies and sea nettles. Local reports suggested there might be some connection with the extended drought that we were/are experiencing and that an increase in the salinity of the bay contributed to the presence of the jellies.

What I actually found on my walk that day was the eroded remains of some of these creatures. I can’t be sure which ones because there was not much left. The more delicate tentacles and tissue wear away in the intertidal, leaving the denser mesoglea in the surf. Mesoglea is the gelatinous material between the outer and inner cell layers of the sea jellies. It is made of collagen-like connective fibers and tissues. The material is actually pretty resilient, feeling more like a contact lens than like jello.

Coincidentally, the Beachhunter also has a gelatinous post up today. Check out David’s entry Man-of-War Jellyfish Video Clip & Photos.

Also, if there are any budding biologists out there who would like to answer this question, you have a few days left: Why is the mesoglea really thick in medusa and really thin in polyps?

References

• Ruppert, Edward and Richard Fox. Seashore Animals of the Southeast. Columbia: University of South Carolina Press, 1988. pp. 26.
• Witherington, E., Blair and Dawn Witherington. Florida’s Living Beaches. City: Pineapple Press (FL), 2007. pp. 39.

Additional Links

• Sarasota Herald Tribune: Jellyfish inundate Southwest Florida bays; drought may be to blame
• BeachHunter.net: Man-of-War Jellyfish Video Clip & Photos

Tags: beachcomber, cnidarians, sea jellies

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