Sanibel’s beaches have recently been covered with a variety of sea life, most likely washed ashore due to the high winds created by the recent storms. Among all of these creatures, you may have noticed quite a few long, thin, squishy animals. Many beachgoers have stopped in to ask us what they are.
These animals are called Sipunculid worms, or more commonly peanut worms, due to the fact that their body is the shape of a shelled peanut. They are found throughout the world's oceans, spending most of their time burrowed into the sand on the sea floor. Some species, however, spend their lives living in the crevices of rocks or inhabiting empty shells. These bottom dwellers are not very well studied; there are about 300 defined species of peanut worms, but it is estimated that there could be up to 500.
Peanut worms are completely unsegmented invertebrates, and not highly variable in color, usually brown, tan or white. The majority of these worms are only found to be a few centimeters long, but some can grow up to two feet. They are detritivores, feeding on the dead particles that they find buried in or on top of the sand.
The bodies of peanut worms are unique in the sense that their mouth is located at the end of a small tube on one end of their body called the introvert. Tentacles located on the introvert are covered with cilia, which allow the peanut worm to grab its food. Once it has possession of the food, it is able to completely withdraw the introvert into its body to eat it. This allows the majority of the body to remain safely burrowed in the sand while the animal searches for food.
Maybe they aren't the cutest creatures in the sea, but we think finding them makes for an exciting beach walk!