Hydromedusae in bloom

Spring is here and the harbor is truly coming alive—boats are returning to their moorings, people are creeping out to bask in the sunshine and the hydromedusae are blooming. This is a hallmark of spring that aquarist Jackie Anderson always looks forward to!

Jackie collects a few hydromedusae from Boston Harbor and uses the pitcher to transport them
back to the holding tanks behind the scenes at the Aquarium.

Jackie is one of the people who takes care of the jellies that you see in the Aquarium. She's also the force behind one of our newest exhibits—the fleeting hydromedusae display near the Edge of the Sea tidepool touch area.

Jackie inspects the tiny hydro medusa recently collected from harbor waters 

Hydromedusae belong to a group of animals that are classified as Cnidarians. Cnidarians include corals, anemones and jellyfish. Hydrozoans begin life as a stationary hydroid (more on that later). Some species remain in this stage, but many others can release free-swimming jellies known as hydromedusae.

In the free-swimming stage, they can look very similar to some of the jellies you see at the Aquarium with the bell shape and tentacles flowing beneath. To get around, these animals pulse just like a sea jelly, too. However, they rarely grow larger than your fingernail and most are nearly translucent.

See they tiny jellyfish-like swimmer in the beaker?

Jackie has been monitoring Boston Harbor for these fascinating gelatinous zooplankton and has been collecting some for display. "I'm fascinated by these animals," she says. "I want to be able to show other people that they are a part of our local ecosystem, you just have to look closely."

This book doesn't come close to identifying all the hydromedusae we encounter

One type of hydromedusa that we often see this time of year is Sarsia. They have the usual bell-shaped umbrella, with four canals and four long tentacles and a mouth-like clapper hanging below. They reach a maximum of only 18 mm high!

Sarsia tubulosa 

We also see what is likely Tiaropsis. These are flatter shaped and look more like miniature moon jellies.

Many hydromedusae look similar, but we believe this is a Tiaropsis

As mentioned above, the free-swimming jellies are just one part of the life cycle of hydromedusae. When they're not pulsing around the surface of the water they are anchored to rocks or pilings at the ocean's floor during the hydroid stage, long filaments studded with polyp. When the polyp is ready, the polyp breaks off into tiny hydromedusae. (Here's a helpful diagram about the life cycle of moon jellies.)

The hydrozoans (a different species from the hydromedusae above) spend much of the year in the hydroid stage,
which are the little nubs along these filaments attached to the glass.

There's still a lot to learn about these tiny seasonal neighbors of Boston Harbor. Come by the Aquarium and see if you can spot these ephemeral jellies in our special exhibit. Or if you're near the shore this time of year, look closely. You might see a glint of tiny tentacle flitting across the surface.

Flat-calm water, a good eye and a trusty scoop is what you need to spot the hydromedusae in the water. 


Small Wonders Around the Aquarium

As winter tightens its grip on New England, what better place to spend a cold, windy day than the New England Aquarium! With thousands of animals to see and different exhibits to explore, it’s the perfect place to slow down and pretend it’s almost springtime.

While some of the larger animals instantaneously grab your attention (Myrtle comes to mind), take a closer look and you might discover some smaller, but no less amazing, animals. Not sure where to begin? There's a treat flitting around the seahorse exhibit on the third level of the building!
Juvenile trunkfish gets his close-up
While it’s difficult to find the seahorses entwined in the different seaweeds and grasses (or each other), it’s even more difficult to find the juvenile trunkfish! Only an inch and half long, this fish is normally found in the Caribbean. As juveniles, however, they can get pushed north by the Gulf Stream and find themselves off the coast of New England, where they would die in the chilly winter waters if aquarists hadn't rescued them during warmer months. Though boxy in shape, this little guy can move around quite easily and will grow much bigger, perhaps finding a home in the Giant Ocean Tank. (And speaking of adorable, don't miss video of a juvenile cowfish that rescued in similar fashion.)

Can you find the trunkfish in the seahorse exhibit?

Right around the corner from the seahorse exhibit is a tank with a slanted top. Located in the Edge of the Sea touch tank area, this exhibit showcases local New England animals that are too small to interact with visitors. It’s a fantastic way to see juvenile flounder, tautog and skates swim along the sandy bottom. Also located in this exhibit is a native shark species!

Can you find the juvenile shark?

While only growing to about 18 inches as adults, the juvenile chain dogfish are quite small and blend in to their habitat with their distinctive chain-link pattern. If you look closely, you can see their cat-like eye and a small hole right behind the eye. This is a spiracle! It’s a small pump that allows the shark to move water over its gills when sitting still on the bottom: thus, the shark can still take oxygen out of the water even when it’s not moving! (Don't forget about the shark nursery on Level 1, too!)

Look closely and you can see the spiracle located behind the eye.

Located on the first level of the building, the lobster nursery showcases the hard work Aquarium researchers put into learning more about one of New England’s most iconic creatures.

Happy as a clam…in a clam shell

By hatching and growing lobsters, researchers can examine shell growth and what impact diet has on their color and development. Take a closer look and you’ll see a number of uniquely colored lobsters here, including a small orange one hanging out in a favorite hiding place.

Lots of lobsters!

The Yawkey Coral Reef Center, on the fourth floor of the Aquarium, highlights all types of animals from the Bahamas. Look closely in the circular tank with long sea grass habitat, and you’ll discover one of the Aquarium’s smallest inhabitants-the dwarf seahorses!

Home sweet home

The dwarf seahorse (Hippocampus zosterae) is one of the smallest seahorse species in the world! Only growing to a maximum of two inches long, these small seahorses utilize sea grass beds as a habitat, using their flexible tails to hold on against the currents. Like their larger cousins, dwarf seahorses are lie and wait predators, waiting for a small copepod to swim by before they pounce, quickly sucking the food through a trap door at the end of their snout. If they are this small, imagine how small their prey must be!

So as the snow falls and the winter trudges on, visit the Aquarium. Take your time, look closely for the small animals that call Central Wharf home and enjoy some time out of the cold...before the next snow storm descends!


Introductions: Common tern, meet a fellow common tern!

Our new common tern was introduced into our Shorebirds Exhibit on December 3. Before that, we'd sent out some of her feathers to a laboratory where the sex of the bird was determined through DNA analysis, as male and female terns look almost identical. While the bird was in still quarantine, we learned that she was a female.

Ike stands on the left, Truro on the right

We also gave her a name, Truro. In the exhibit, Truro joined our other female common tern, Ike, as well as eight other birds. Because Ike had been the only tern in the exhibit since she was introduced as a juvenile almost seven years ago, we were uncertain as to how the terns would react to each other.

Truro on the left, Ike on the right

Surprisingly, Ike, the older bird, was afraid of Truro, while Truro was eager to be around other terns and would try to approach Ike. Over several weeks, Ike began to warm up to Truro and although they don’t interact very much we often see them standing within a foot or two of each other. Both terns have also been trained to approach the door of the exhibit to get fed their morning fish with a vitamin inside of it and Truro has caught on to the routine very quickly.

Come visit the shorebirds exhibit and get to know some of the beautiful birds on your local beaches! Here are some of the animals you'll find:


A lobster with spines

The Caribbean spiny lobster (Panulirus argus) can be found from North Carolina and Bermuda south to Brazil—and also in the Aquarium's Blue Hole exhibit, where they share the space with some impressive goliath groupers.

Spiny lobster—note the absence of the powerful front claws that American lobsters have

While Caribbean spiny lobsters are nocturnal, you can find them scurrying about the dim exhibit or resting in their favorite den. They are about a foot long, though they can grow to be longer than 3 feet and weigh 15 pounds in the wild!

Spiny lobster in the Aquarium's Blue Hole exhibit

Caribbean spiny lobsters are one of approximately 30 different spiny lobster species found in tropical and sub-tropical waters around the world. They can migrate long distances in single file lines called queues. This species can live down to depths of about 1,650 feet and feed on gastropods, bivalves, and carrion (dead things). Moray eels, nurse sharks, groupers, turtles and sometimes octopus are among the animals that prey on these animals.

Spiny lobster queue | Photo: Florida State University Herrnkind Lab

Unlike the American lobster they lack large claws and have spines covering their body for protection. Like their American lobster cousins, Caribbean spiny lobsters have long antennae on the front of their carapaces for defense. Caribbean spiny lobsters also shed their shells in order to grow bigger like other crustaceans.

Caribbean spiny lobster with antennae | Photo: Becky A. Dayhuff via Wikimedia Commons

You can sometimes find an Aquarium educator holding a molt, which was collected after an animal in the Blue Hole exhibit shed its shell. This happens when lobsters split their shell into two pieces and squeeze out, leaving the molt behind. Look out for this biofact because it's a great way to get a feel for those spines that give this lobster its name!

Conservation Notes: Caribbean spiny lobsters are a popular seafood and commercially fished. The fishery is regulated with size, season, egg-bearing and trap limits. The population of the Caribbean spiny lobster is healthy.

Look for other lobsters throughout the Aquarium! Can you find relatives of the Caribbean spiny lobster in the Isle of Shoals, Boulder Reef, Lobster Nursery and Edge of the Sea exhibits? 

— Meghan-Elizabeth Foster, Visitor Educator


New Arrival: A Common Tern

In October we were lucky to have the opportunity to acquire another bird for our Shorebird Exhibit, a juvenile common tern. Common terns are smaller and more delicate than their relatives the seagulls. They are graceful fliers and you may have seen them at the beach, hovering in the air before plunging into the ocean to catch small fish. They breed in Canada and the Northern US and migrate to the coast of South America in the winter.

Our common tern in holding

Despite their name, common terns have experienced large declines in their population. They were hunted for their feathers in the late 19th century and were harmed by pesticide use in the 1970’s. Today they continue to be threatened by coastal development.

This tern was discovered emaciated and unable to fly on a beach near Orleans, MA, on Cape Cod in late August. She was brought to Wild Care where the rehabbers discovered that her right wing was injured. She had no fractures that were detectable from radiographs, so the injury was likely due to a torn tendon or ligament. The tern lived in an aviary through September and into October while her care-takers waited to see whether her wing injury would heal so that she could be released to migrate south with other terns in October. It became clear that the bird would not be able to fly well enough to be able to fish or migrate.

New England Aquarium staff picked her up in late October, just in time before some cold weather set in! The tern went into quarantine in an indoor enclosure. We were pleasantly surprised by how calm she was around people. She would squawk loudly in the morning to remind us that it was time to be fed her first fish of the day!

Our new common tern came to us from the same wildlife rehabilitation facility, Wild Care, as our semipalmated sandpiper. The exchange of these birds was mutually beneficial—Wild Care found a good home for two non-releasable birds and the Aquarium now has two great new exhibit animals that will help educate the public about shorebirds and their conservation.

Stay posted for an upcoming blog about the tern’s introduction in the exhibit.