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Six Underwater Beauties Not to Miss

A family in Underwater Beauty peers through a habitat teeming with quick-moving, many-shaped reef fish.

Shedd’s new special exhibit, , is a feast for your eyes and your curiosity. Who knew there was so much shimmer, color, pattern and rhythm (especially among shrimp) in our oceans, lakes and rivers? As you explore this inviting space, with its rainbow of fishes and invertebrates and a panoply of patterns in motion, don’t overlook these astonishing beauties.

Underwater Beauty Neighborhood Murals

Dive into a world of beauty worth saving with street art across Chicago, from Edgewater to Bronzeville, all inspired by the diverse animals of Underwater Beauty.

Flower Hat Jellies in Underwater Beauty

Flower hat jellies

This sea jelly species is not new to Shedd Aquarium, but its presentation is. In regular light, flower hats look like Derby Day chapeaus, in pinks and greens, with ribbon-like tentacles. But bathed in cobalt blue light that’s the same wavelength as the jellies’ natural environment, the glowing green tips of their waggling tentacles dance in the water like drifting phytoplankton.

The jellies are ambush hunters, coiling and uncoiling those tentacles to attract curious small fish prey looking for a nibble, then stunning them with venomous nematocysts, or stinging cells.

The fluorescence comes from green fluorescent proteins, or GFPs, that are found in hundreds of marine species. The protein molecules reemit absorbed light at a different wavelength that might resemble the color of chlorophyll to grazing fishes.

The green display in the rainbow wall in Underwater Beauty features a lush array of aquatic plants, some with long, thin leaves like grass and some with fat, round bushy leaves.

Green plants

“I love a good planted habitat,” says Mark Schick, special exhibit collection manager, peering into the green display in the rainbow wall that ushers guests into  Colors room.

Among the more than dozen plant species, you might recognize the long, grasslike Cryptocoryne spiralis and another Cryptocoryne species commonly known as water trumpet, both mainstays of hobbyists’ freshwater aquariums. Another familiar plant, the Java fern, has deeply veined leaves that look like fronds, while the Java moss looks like an underwater asparagus fern. The tiny leaves carpeting the bottom are Glossostigma elatinoides, or glosso for short.

Punctuating this aquatic garden are green neon tetras and inch-long neocaridina shrimp that you’ll most likely see sitting on an arching stem, eating the biofilm of algae and microorganisms on the leaves. Look for the shrimps’ two color morphs among the greenery—blue and yellow. “That’s aquarist humor,” says Mark.

A rugose clam attached sits attached to a rock with its wavy, ridged shell slightly ajar, the clam's body peeking out.

Giant clams

The giant clams of the genus Tridacna come in all sizes, including a dwarf species, which you can see in Underwater Beauty along with the large blue-green giant clam, shown above, center. When you look a giant clam in the eyes—you’ll have to squat to do it—it’s peering out with several hundred pinhole-type eyes that dot the slightly curled-over edge of its mantle, or fleshy external surface. The eyes can detect movement and differentiate between light and dark. Something dark and moving makes the clam snap shut with a startling jet of water through its siphon.

Look closer at the differences among the clams on display: the blue-green T. derasa, the largest specimen, has a subtle light-and-shadow pattern on its mantle. T. squamosa has a strongly fluted shell. The smallest in the habitat right now is T. maxima, commonly known as the small giant clam. (Size is relative among Tridacna clams: T. maxima grows to about 1.3 feet long, one-third the size of the biggest of the big, T. gigas, truly giants at up to 4 feet and 660 pounds.)

The squiggles of color in the clams’ mantles are tubes of zooxanthellae, photosynthesizing algae that live in a symbiotic relationship with the clams, providing them with food and deriving protection from the fortresslike mollusks. (Many corals also have zooxanthellae.) Like our fingerprints, no two clams’ patterns are exactly the same. Clams also produce their own pigments in their mantles that Mark likens to “natural suntan lotion.” The pigments, often shades of blue or purple, reflect sunlight so that the clams’ soft mantle tissue doesn’t burn in shallow sunny waters.

Glass catfish are small, a little shorter than a pinkie finger, with almost completely transparent bodies through which you can see their thin, fine bones.

Glass catfish

Around the corner in the Rhythms section of the exhibit, you’ll find small freshwater fish that have taken protective coloration to the extreme: They’re transparent. The glass catfish, which ripple to keep their place heading into a current, are living X-rays.

Like all catfishes, they lack scales, but this species also lacks pigment. Most of the fish’s organs are concentrated in the head area. Then there’s the spine, ribs and cartilaginous rays of the fins in a body so clear you can see through it to the background vegetation. Look closely and you can detect the clear fins rippling, moving the fish forward. But you can’t see the muscles that are doing the work. Pulsing in a nearby habitat are the equally transparent moon jellies. This is beauty you can’t see.

Beauties-in-motion video

The interactive motion wall in ’s Rhythm section is fun, but after you swing your arms and shuffle your feet to activate animated animals, don’t turn your back on the video on the opposite wall. It asks, “If you lived in the water, how would you move?” Assorted aquatic species provide examples of just how many ways an animal can get around underwater. The short video is worth watching a few times for the sea star’s thousands of tube feet on the march and the cutest balled-up little octopus rolling across the seafloor on three rotating arms.

Two guests dance with the video in the rhythm section of Underwater Beauty.
  • Blue discus, with their round coin-like bodies about the size of one's palm, tend to swim in the middle range of the large freshwater habitat at the end of Underwater Beauty, Shedd's special exhibit.
  • The Goyder river rainbowfish can usually be found in the mid-level of the freshwater habitat in Underwater Beauty, Shedd's special exhibit.
  • The Lake Kubutu rainbowfish lives in fresh water and has a small orange bump between its large round eyes.
  • Suckermouth Catfish in Underwater Beauty
  • Cupid cichlid in Underwater Beauty

Freshwater beauties

So far, most of the shimmery, colorful, patterned, rhythmic creatures in  have been residents of saltwater realms. In the final room of the special exhibit, Move You, fantastic freshwater fishes are in the spotlight. You’ll find more species here than in the large Patterns habitat.

Take advantage of the half-circle bench seating to enjoy the panorama, but do let the fishes move you up close to the glass to really look at how beautiful each type of fish is. The tropical South American, Asian and Australian species will be familiar to fish hobbyists. They range from the tiny tetras, like the neons and fireheads, visible above, to saucer-sized blue discus.

Mark suggests looking at how the fishes divide themselves among the top, middle and bottom levels of the habitat. You’ll find lots of the smaller fishes congregating near the surface. The aptly named checkerboard pencilfish are slender with a check pattern on their sides. Another species that lives up to its graphic common name is the marbled hatchetfish. Each small fish’s deep belly has swirls of brown and cream, set off by a gold line that runs from its eye all the way to its caudal, or tail, fin.

Standing out among the little fishes are the 6-inch-long Goyder River rainbowfish, shown above, with their brilliant red dorsal, anal and caudal fins. Males have a dark horizontal stripe running the length of the body.

At mid-level, it’s easy to spot the Cupid cichlid with the large eyespot near the tail, above. Prominent eyespots can trick a predator into backing away from what looks like a much larger animal or make it look like prey is coming when it’s really high-tailing it away.

Along with the blue discus, whose aqua fins are edged in red scribbles and scrawls, another of the most beautifully hued species is the red rainbowfish, which glitters with gold flecks when the light hits its scarlet scales just right. The shimmering three-lined scissortail rasboras’ forked tails are marked with three bands of white, black and white.

Look among the vegetation for interesting nibblers. Suckermouth catfish, shown above, hop along branches, scraping off organic matter. The flying fox sharkminnows, with bold horizontal stripes of rusty red and black, graze on the algae that grows on leaves.

“Don’t neglect the bottom,” Mark advises. That’s the domain of the corydoras, also known to hobbyists as cory catfishes. This large family of small, energetic scavengers from South America includes the intricately spotted leopard catfish.

Overhead, mirrored mobiles literally reflect the movement of the tropical fishes and add to the gentle kinetic serenity of this last stop. But while the freshwater fishes are a subtler pleasure than the chromatic fireworks and fancy dancing of some of the reef animals, they sparked a “wow!” from one young guest while two others exited doing swim strokes. That’s how they’d move underwater.

 is free with aquarium admission.

—Karen Furnweger, web editor