Posted by: leahbiery | May 28, 2010

Oil or Animal?

"Sea pork," a tunicate commonly found on Sanibel beaches.

Due to the widespread uncertainty regarding if and how the oil blowout will affect Sanibel Island’s beaches, Sanibel Sea School has been receiving lots of questions about the topic from citizens and visitors.

A few people have expressed concern over dark blobs on the beach, wondering if they have found the first signs of oil on our island. If you come across the lumpy objects pictured at left, don’t panic – they are just tunicates, perhaps the most highly-evolved marine invertebrates. They are also known as “sea pork” or “sea hams,” and are related to sea squirts.

Sea pork is a firm mass of cellulose that houses many zooids, which are tiny distinct individuals that form a colonial animal. The subtidal species grows on rocks, jetties, corals, and seaweed, and often gets washed up on the beach during storms. They are filter feeders, meaning they derive food from the saltwater that they pump through their bodies.

How can you tell if you’re looking at a glob of oil versus a glob of sea pork? Sea pork is firm, smooth, and flexible. It appears and feels very much like rubber, and comes in many colors. If you look closely, you will be able to see the thousands of zooids that make up the larger organism. It’s like an apartment building full of tiny residents.

Oil usually shows up on beaches in the form of mousse or tar balls. Oil mousse is brownish-orange in color, with the consistency of thick pudding. Tar balls

Photo Credit: Mike Valiquette, PURRE

are black, very dense in weight, and feel sticky.

If you think you’ve found oil, report it to local officials for further investigation. If you find a piece of sea pork, enjoy the opportunity to take a closer look at a very interesting marine organism.

Photo Credit: Mike Valiquette, PURRE

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