Jellies are found in a number of areas around the Aquarium. You can find them on both floors of the West Wing (the same area where you can find our new Trust Family Foundation Shark and Ray Touch Tank), in a number of behind-the-scenes areas and also on the second floor in the Thinking Gallery. While the species on display are known to change, we currently have a beautiful species known as flower hat jellies (Olindias formosa).



These intricate animals are found naturally off the coast of Southern Japan, Brazil and Argentina. They are thought to be quite rare, but their conservation status is not currently known. While they don’t move around that often, they certainly can. Like all true jellies, or cnidarians, they have stinging cells called nematocysts. A flower hat jellies’ sting is painful, but is usually non-lethal to humans. You can read more about jellies on a previous post.



Flower hat jellyfishes, photo courtesy Fred Hsu via Wikimedia Commons

These jellies eat mainly small fish and crustaceans. Here at the Aquarium they are fed live zebrafish. There is no set feeding schedule, so getting to see them fed is just luck of the draw (as a hint, they are at varying times on Saturday, Tuesday and Thursday). It’s a pretty interesting feed. Check out the video below to see how it works!




See you in the galleries!

-Sam

This is a follow-up to a previous blog post. Learn about different kinds of sea jellies and their unique characteristics here.

 
Black Sea jelly, via Wikimedia Commons

"True Jelly" reproduction 
One remarkable trait of most Scyphozoans is their dual reproductive strategies. They can produce asexually by budding and sexually after a process called strobilation. The fertilized egg becomes a planula larva that quickly settles and morphs into a polyp. This polyp then becomes a strobila – almost looking like a stack of coffee filters. Each of these detaches and becomes an ephyra which then transitions into either a male or female medusa to begin the process all over again.




Jellies are beauties, adaptors, predators, survivors, neighbors...
If this year is anything like last we will see a fairly large population of jellies in the harbor pretty soon.  They thrive in warmer water, but humans also play a role in helping jelly populations.

Credit: NancyHeise, via Wikimedia Commons

Overfishing – Humans can overfish the natural predators of jellies, creating a host of problems. By removing their predators, namely large fish, it allows populations of jellies to grow exponentially.  Since jellies in turn eat larval fish, increased jelly populations further reduces already overfished populations.




Pollution and runoff – Pollution and runoff can cause what's known as "dead zones," areas that are severely depleted of oxygen. While these conditions are inhospitable to fish, they are a fine environment for jellies.








Invasive species – Many invasive species are introduced to oceans around the world through the ballast
waters of boats; and invasive jellies are no exception. A famous example is the comb jellies that were introduced into the Black Sea in the 1980's. They have no natural predators and have wiped out many commercial fisheries. By 2000, the total weight of the comb jellies in the Black Sea was more than 10x all the commercial fish caught there throughout the entire year.

What can you do?
There are lots of ways you can support healthier oceans, including hoofing it now and then and choosing ocean-friendly seafood. Explore ways you can LiveBlue™ at the Aquarium. Come see jellies up close and learn even more about these fascinating creatures in The Trust Family Foundation Shark and Ray Touch Tank area, opening April 15!

Most people think of jellies as clear, squishy blobs of goo that sting and ruin your day at the beach. You can see them in several places throughout the Aquarium. The common image in most people's minds looks somewhat like an umbrella with long strings dangling. While this is what many jellies look like, to a biologist the term "jelly" can refer to a huge range of animals that have existed on the planet for around 650 million years! Let's explore...



Jelly Classification
When classifying jellies the best place to start is the phylum Cnidaria, so named because of the venomous cells called cnidocytes that are unique to animals in this phylum. Cnidaria is most commonly divided into four classes and perhaps the most well known class is Scyphozoa – sometimes referred to as "true jellies," or those umbrella-shaped jellies mentioned earlier.



Some examples at the Aquarium would be moon jellies and our pacific sea nettles. Another well represented class at the Aquarium that you may not have even realized is a cnidarian is the class Anthozoa – the corals and sea anemones. The last two classes are Hydrozoa (hydroids, Portuguese man-o-war) and Cubozoa (box jellies, sea wasps).

Moon jelly © Hans Hillewaert / CC-BY-SA-3.0 , via Wikimedia Commons

The second most prominent phylum referred to by the name "jelly" is Ctenophora, the "comb jellies." The most prominent feature of these animals is their comb-like cilia that they use to swim. Ctenophores differ from cnidarians in a few ways, perhaps the most important being that ctenophores do not have cnidocytes, and thus they cannot sting.



Comb jellies, credit: Überraschungsbilder, via Wikimedia Commons

Common Characteristics
Jellies are invertebrates made of about 95% water, so as you can imagine they are pretty fragile. Jellies consist of two or three layers of cells formed around a central opening – this organization of similar parts around an axis is known as radial symmetry. Despite the fact that they do not have a brain, heart, real digestive system, complex eyes OR a respiratory system they are still effective predators of mainly zooplankton. Jellies that move do so by pulsations of their bell, but many species are sessile and don’t move at all. Or, some species are sessile at one stage of their life and then begin to free swim.

Which leads us to sea jelly reproduction! As the weather warms up, you'll likely see loads of jellies in Boston Harbor (see this blog post for evidence). Keep checking the Exhibits Blog to learn how sea jellies reproduce and to find out why there are just so many jellies in oceans today!