Guest commentary: What is that on the beach?

Nancy J. Richie
Island Environmental & Marine Services, LLC

Walking down the beach after a high tide or summer storm and especially after a hurricane, many unusual marine organisms can be found. Some are more unusual, even unsightly and alarming, than others.

So many beautiful shells, interesting soft corals and other flotsam will wash up due to Hurricane Irma; some not so beautiful. One such organism lacking in beauty to most, Aplidium stellatum, or commonly known as “sea pork” due to its globular, rubbery, cartilaginous form, is found along Florida on the east and Gulf of Mexico coasts.

On Marco Island beaches, after large tidal events and storms from the southwest, this marine colonial tunicate (sea quirts) that dwells in nearshore shallow waters, lives on the Gulf floor and attaches to structures such as pilings, rocks or seawalls, washes up in all sizes and shapes. Wave energy or tidal and storm currents can knock them loose causing them to wash up on the beaches.

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Sea pork comes in many shapes and sizes and brilliant colors, from purple, red, orange, pink, even spotted like a cheetah’s coat, but once washed up, the sun and heat can quickly dry it to a white, grayish or black color, looking like pork fat or backstrap, giving its common name. Seeing this not so beautiful organism as you beachcomb could be alarming and you may easily identify it as a glob of oil, which did happen many times during the BP Oil spill, or as, disgustingly, human excrement.

To quell that alarm, take a closer look, as close as you can manage, and you will see the hundreds and thousands of little round circles, like pores, covering the globular, shiny surface. Not oil or excrement, but a living organism as those little round holes are individual zooids.

When larvae, which look like minuscule tadpoles, gather and settle down, they attach as a group to the Gulf bottom, rock or dock and excrete cellulose they produce by filtering the sea water, creating the sea pork mass. The mass can be an inch to larger than a foot in size. The larvae eventually become the zooids, which are small individual animals that live in a colony (like coral), creating the lumpy, shiny mass covered in the tiny round holes of sea pork. The individual zooids are filter feeders, each with its own incurrent siphon for taking in nutrients from the seawater and out-current siphon for excreting wastes, constantly filtering the water. Many bottom dwelling fish, sharks, skates and rays eat and depend on the sea pork for their diets.

Now, if you feel more inquisitive, take a whiff. The marine organism will smell, well, like low tide or organic, not of hydrocarbon (oil) or, thankfully of human waste.

So, while you are enjoying the beautiful Marco Island beach, look for sea pork. It is a sign of a healthy ecosystem. Though not attractive to most, this common invertebrate colony of the nearshore waters of the Gulf, Aplidium stellatum, like many such tunicates, is very important to the water quality and ecosystem of the Gulf of Mexico and the beaches.