Sea pansies are a treat to find while walking our Lowcountry beaches during the day, but also at night for their beautiful bioluminescent glow.
The first time that you see one you may be confused as to what it is. They look like purple petals, and often you are not quite sure if it is a plant or a creature. In fact, they are a spongy Anthozoan colony. In easier terms, they are a colony of organisms that create the larger pansy that we see. They are closely related to anemones and soft corals.
Sea pansies, Renilla reniformis, can be found along the sandy coast from North Carolina all the way to Brazil, but they are not found in the Gulf of Mexico. They are a petal-like frond that can reach up to 3 inches in length. Their purple coloring is derived from calcium carbonate inside of their tissue. Sea Pansies are spectacular to view at night, if they are disturbed, they will glow green with bioluminescence.
These colonial creatures can be found singly or in larger groups. They anchor their stalks into sandy substrates, such as our beaches and sandbars. They are made of a collection of polyps. One type of polyp creates the anchoring stem of the animal. Another type of polyp creates a body that contains the anemone-like feeders. The feeders release a sticky mucus onto their tentacles that capture plankton suspended in the water. There are tentacle-less polyps that act as an outlet valve. These polyps will deflate the sea pansy if it is exposed at low tide. They deflate so that a layer of sand will cover the whole pansy and keep it safe until the tide rises again. There are also polyps that look like white dots in between the feeders that act as inflating polyps. These will re-inflate the pansy as the tide rises. All these polyps together, create the Sea pansy that we find.
These amazing creatures are able to reproduce in two different ways. They can reproduce asexually where they create a bud-like polyp on their exposed surface. This polyp will then detach from the main body and free float until it has fully developed. They can also reproduce by releasing reproductive materials into the water column. These gametes will then become fertilized, creating new polyps that will mature in the water column.
Sea pansies usually end up in our beachcombing zone due to rough waves and strong currents that dislodge their anchors. If you find them on the beach you can check if they are still alive by placing them on the sand under the water. It may take a little while, but you may be able to see the feeding polyp tentacles begin to move as they search for food. You may also see the anchor work to re-attach the pansy to the sand. Humans are their largest predator, by removing them from their habitat. In the water their only natural predator is the Striped Sea Slug.
Sea pansy is a great example of how nature can be so complicated in what looks like such a small creature! They are the beautiful Pansies of the sea. Keep an eye out for these amazing animals while beachcombing during the day, but also at night for their beautiful bioluminescent glow.
By Kathleen McMenamin, Master Naturalist
Kathleen McMenamin is a certified Master Naturalist, 50Ton Master Boat Captain, ACA Certified Stand Up Paddle Board Instructor, and US Waterski Certified Ski Instructor. Her love for the outdoors stemmed from growing up on Hilton Head. She has traveled throughout the world, but her passion lies in the South Carolina Lowcountry. She spent her childhood exploring the outdoors, surfing the beaches and paddling the creeks. She has been a guide in the area for over 14 years. She now splits her time between Hilton Head Island and the Blue Ridge Mountains outside of Asheville, North Carolina. She is always exploring, learning all about her natural surroundings, and sharing it with others.
Our featured Sea Pansy photo was taken on Hunting Island Beach by Merranda Michels.