By: Emily Sampson
When it comes to jellies, sometimes we feel their presence before we actually see them. While this may be a bit unnerving to humans, these fascinating creatures have been drifting in the seas for over 500 million years and are an important link in the marine food chain. Many sea jellies pack a powerful sting, so it is important to know the difference between the harmful and the not so harmful.
Here is a list of 5 sea jellies (or jelly-like creatures) that you may encounter around Sanibel and in the Gulf of Mexico:
Moon jellies are easily recognizable by the 4 petal-like reproductive organs that can be seen through their bell.
Moon Jelly - Aurelia aurita
Moon jellies are the most common species found around Sanibel. Like all jellies, this species isn’t an excellent swimmer but is able to pulse its sac-like body called the bell, through the water. Moon jellies have short tentacles along the outer margins of the bell that are packed with nematocycts, or stinging cells. Jellies use these cells to aid in capturing prey and for the moon jelly, is zooplankton. Not to worry though, their stinging cells aren’t strong enough to penetrate human skin and will only cause a very mild irritation.
These graceful jellies mostly consume zooplankton but their powerful nematocysts allow them to consume larger prey, such as minnows and small crustaceans.Their sting can also produce a moderate irritation in humans.
Atlantic Sea Nettle - Chrysaora quinquecirrha
Sea nettles possess several long tentacles and long, trailing oral arms. What's interesting about these jellies is that their colors vary depending on salinity levels and therefore may appear transparant or white when found in brackish waters on the bayside of Sanibel. When found in the saltier waters of the Gulf, red and brown streaks radiate from the center of the bell.
The cannonball jelly has tiny "warts" located on its bell that are packed with stinging cells.
Cannonball Jellyfish - Stomolophus meleagris
Also known as the cabbage head jellyfish, it’s easy to guess where these jellies get their name. When floating, cannonball jellies take on a spherical shape with multiple, stubby oral arms peaking from underneath the red-fringed bell. Cannonball jellies play an important role in the marine ecosystem because they are the preferred prey for the endangered leatherback sea turtle. In addition to being a food source, they also form symbiotic relationships with fish and juvenile longnose spider crabs.
Drymonematidae is the name of the recently added family of jellies and thanks to the pink meanie, it is the first new family of jellies since 1921.
Pink Meanie - Drymonema larsoni
A newly described jelly, the pink meanie, was initially observed about 15 years ago in the Gulf of Mexico during a massive moon jelly bloom. When scientists took a closer look, they noticed that this jelly was feeding on the moon jellies and that it was drastically different than anything that had seen previously. It was so distinct, that they created a new family just to classify it! These pink meanies were collected for study near Dauphin Island, Alabama but are extremely rare elsewhere. While they may not be seen commonly in the waters near Sanibel, you never know what could drift along the currents and surprise us all!
Comb jellies have a simple, gelatinous body much like true jellies but they aren't in the phylum Cnidaria. Instead, they are classified as Ctenophores because they lack specialized stinging cells.
Comb Jellies - Ctenophoroa
These jellyfish look-alikes are not taxonomically related to jellies but we think these creatures are too interesting not to share! Their beautiful ovoid bodies are lined with thousands of tiny hair-like structures called cilia that they use to propel themselves through the water, often illuminating with bioluminescence. Even though these jellies may look similar to jellyfish, they have a major difference that is perhaps in our favor – they don’t sting! That’s right, these gentle jellies do not have nematocysts. Instead of using a powerful sting to capture their prey, they use colloblasts, which are sticky cells that essentially glue their prey to their tentacles. So, have no fear in handling one of these delicate creatures!