Ever wonder the story behind the treasures that wash up on the beach? While at the beach, we collect interesting shells, egg pouches, and washed up aquatic plants and investigate their stories. Some things I already know and can explain to Skyla directly and others we look up in a book. Two of our favorite books are The Nature of Florida’s Beaches (Cathie Katz) and Florida’s Living Beaches (Blair and Dawn Witherington). Finding treasure is a great platform from which to incorporate various writing exercises, storytelling, counting, art, etc. Here are some images and stories behind what we have found…
Lightning whelk egg cases are the most common cases found along the beach here in Florida. Sometimes you can look inside the casings and find tiny, perfectly formed whelk shells. This particular egg casing did not have any shells left, which means they all hatched out before the casing washed ashore.
Mermaid’s purses are egg cases of a skate or a shark. Shark’ purses have four long tendrils that help anchor the casing. Skate purses have tendrils too but are more pointed (like the one pictured at right). The egg cases are gelatinous and harden upon contact with the water. I found a YouTube video of a newly hatched clearnose skate and its egg case.
Often times shells you find along the beach have holes or lines in them. If your shell has a single hole, the mollusk was likely eaten by a gastropod. Some species drill straight holes and others are slightly beveled. If your shell has a lot of scattered holes, like the one at left, it was likely eaten by a boring sponge. Shells with squiggly lines were eaten by polychaete worms. The worm’s body is bristled and as it rasps, it secretes acids which then create the grooves.
For me, one of the most significant treasures I find is sargassum weed, because it tells a much larger story. This is the ‘seaweed’ you see scattered across the beach…it is actually a yellow-green algae. The brown, dried-up, often odorous masses are remnants of a once vital and very important marine plant. Mats of sargassum weed are the base of an entire ecosystem. The mats provide food and refuge for hundreds of animal species including baby sea turtles. Some
species attach to reefs and become dislodge during storms. Two species, however, are completely pelagic — they never attach to the ocean floor. If you look closely you will see small, air-filled bladders. These are air pockets that allow the plant to float.
Mesoglea compose the bell of a jellyfish and anchor the swimming muscles. Sometimes you find actual sea nettles or comb jellies washed ashore and sometimes you just find these sparkling, clear masses that are the mesoglea from jellies that live in open waters.
You can find several species of green algae washed up along the beach.
Sea lettuce literally looks like someone tossed their bowl of salad out on the sand. It is edible raw and often cooked in soups. Manatees and sea slugs eat it too.
Green fleece, also known as green sea fingers, is another kind of green algae.
I’m pretty sure it is the species pictured at left. If so, it is an introduced species. Depending on your source, it was either brought here attached to ships from Europe or it is native to the Pacific Ocean in Asia. I am not sure how invasive it is.
There are so many other treasures from the sea to be found - birds taking a bath in the surf, black skimmers dipping their beautiful bills into the water while on the wing, turtle tracks at dawn…Time to get out off the computer and find some more!