Sea dragon dad glues his brood to his tail for safekeeping, stunning image shows

A gorgeous new image shows a common sea dragon dad drifting through a seagrass meadow with his jewel-like egg clutch in tow. 

The image took the top spot in the Compact Behavior category of the Underwater Photography Guide's 2022 Ocean Art contest.

Common sea dragons (Phyllopteryx taeniolatus) typically live at depths of around 13 to 20 feet (4 to 6 meters), though they can dive down to 160 feet (50 m), according to the Georgia Aquarium. They usually begin brooding in late July or early August. 

The eggs start out a beautiful shade of deep magenta, which fades to brown as the baby dragons develop. Sometimes green or brown algae grows along the dad's tail, helping provide further camouflage. "After a few weeks, you start to see eye spots inside each [egg]", Greg Rouse, a marine biologist at the University of California San Diego's Scripps Institution of Oceanography who wasn't involved with the photo contest, told Live Science. Rouse said that the eggs pictured here are "a pretty fresh brood."

Unlike most vertebrates, male sea dragon parents are the ones who invest time and energy into caring for unhatched eggs. Closely related groups, including seahorses and pipefishes, also display this unusual brooding strategy. However, seahorses and some pipefish sport a specialized kangaroo-like pouch to hold their eggs, whereas sea dragons simply glue their eggs to the underside of their tails. A clutch of sea dragon eggs typically numbers somewhere between 100 and 180, depending on the size of the female.

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All sea dragons are endemic to the waters of coastal Australia. They're notoriously tricky to breed in captivity: Of the three species of sea dragon, only the common (or weedy) dragon has been successfully captive-bred, and not in large enough numbers to sustain a sizable population. "The sea dragons people see in the aquarium are mostly being caught in the wild," Rouse said. To help monitor how this impacts sea dragon numbers, Rouse co-founded the citizen science project Seadragon Search, in which diving enthusiasts can record their encounters with these fish.

Sea dragon dads are far from the only extreme marine parents, and Ocean Art's other parent of the year is a mother octopus. In a stunningly detailed photo that earned best in show, the octopus mom holds her brood carefully in her eight arms, gently wafting water over them to make sure the developing babies get enough oxygen. The photographer identified her as a Caribbean reef octopus (Octopus briareus) and snapped this photo in the balmy waters off of West Palm Beach, Florida. 

"For warm water [octopus] species, the eggs develop pretty quickly. But for colder species they take a lot longer," Mike Vecchione, a cephalopod zoologist with the National Oceanic and Atmospheric Administration who wasn't involved with the photo contest, told Live Science. Researchers from the Monterey Bay Aquarium Research Institute discovered a female deep-sea octopus that held onto her eggs for four years — the longest known brood duration for octopuses. 

The octopus pictured here won't have to wait that long for her eggs to hatch. However, keeping them safe will be the last thing she does. Mother octopuses don't eat or care for themselves while protecting their brood from predators. "They're in pretty bad condition by the time the eggs hatch," said Vecchione, "and as far as we know, they all die shortly after that."