Leafy seadragons are stealth hunters. With plantlike camouflage provided by nature, they float undetected to prey.
But three newcomers to the Florida Aquarium in April had developmental problems. They couldn't float. Just 4 months old, the siblings were more clumsy than sneaky, and day after day, they exhausted themselves swimming. At night, they collapsed to the tank bottom.
Their marathons ended in June, when aquarium scientists outfitted each with a teeny-tiny black swim tube for floating.
"It's like a pool noodle but seadragon-size," said Eric Hovland, the aquarium's associate curator.
Ordinarily a seadragon's swim bladder, a gas-filled sac, inflates to keep a fish from sinking in the water. That wasn't happening for these seadragons, X-rays showed on June 1.
The flotation tubes were introduced on June 14.
To create the buoyancy, an aquarium veterinarian cut pieces of neoprene foam from a wet suit. The strips were then looped around the fish.
The first rings were sutured shut as the seadragons remained in the water.
"These are pretty challenging animals to work with," said Ari Fustukjian, who handcrafted the prosthetics. Because of their leafiness, "you cannot slide something around them," he said.
Since the first effort, the aquarium has used buttons and snaps on replacement tubes, required as the creatures grow.
The seadragons measured about five inches long when they arrived and have since grown to about nine inches, curator Hovland said. As adults, they'll reach 18 to 24 inches.
"At this point we are in an arts and crafts stage," veterinarian Fustukjian said. "We are making new harnesses every two to three weeks."
Once the seadragons reach maturity, within a year, Fustukjian hopes to use a 3D printer to create a permanent prosthetic.
Without the ability to float, they would struggle to survive.
The constant swimming "burns a lot of energy and means they cannot feed themselves normally," Fustukjian said.
By resting on the bottom at night, instead of sidling up to algae on tank walls, they risked surface abrasions, secondary infections or broken fins, he said.
Eventually, the condition would have exhausted them to death, he said.
Providing sea creatures with prosthetics is not new — the Clearwater Marine Aquarium is known for Winter the dolphin's prosthetic tail — but Hovland suspects this is the first flotation aid for a leafy seadragon.
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It may never be known what caused the seadragons' abnormality.
Genetics is one option, Hovland said, or the lighting, food or water depth provided in Australia before the seadragons were shipped to Florida could have stalled their development.
"It could be any number of things," he said.
Hovland estimates that only about 15 aquariums in the United States have leafy seadragons. The exhibit's opening date is not yet determined.
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In Australia, leafy seadragons are listed as a "totally protected species" nearing the endangered category.
If the Florida's Aquarium's three were in the wild with bad swim bladders, Hovland said, "their fate would have been sealed quickly."
Contact Paul Guzzo at email@example.com. Follow @PGuzzoTimes.