A Southern California aquarium has successfully bred the rare weedy sea dragon, the lesser known cousin of the sea horse that resembles seaweed when floating.

San Diego’s Birch Aquarium at Scripps Institution of Oceanography said in a news release Thursday that two weedy sea dragons have hatched this week, making the aquarium one of the few in the world to successfully breed the unusual fish.

The babies with leafy appendages are less than an inch long, and have eaten their first meal of tiny shrimp. The aquarium is keeping the delicate creatures out of public view for now.

The hatchlings come less than a year after the aquarium at the University of California, San Diego built what is believed to be one of the world’s largest habitats for the sea dragons, whose native populations off Australia are threatened by pollution, warming oceans and the illegal pet and alternative medicine trades.

The 18-foot-long tank has 11 weedy sea dragons and three leafy sea dragons, which have never been bred in captivity.

The aquarium hopes to breed the two different kinds of sea dragons so scientists can learn more about the mysterious species. Little is known about them because their populations are so small and in remote areas.

Since 1995, the Birch Aquarium has bred 13 different seahorse species, sharing more than 5,000 juvenile seahorses with other aquariums around the world.

So far, only the weedy sea dragon has been bred in captivity, and only a handful of times.

The Aquarium of the Pacific in Long Beach was the first in the world to breed the weedy sea dragons in 2001. It also is trying to breed leafy sea dragons.