Christopher Mah, a biologist at the Smithsonian, was scouring the museum’s shelves for deep-sea starfish when he had an idea: Why not see if any of the specimens were preserved with their last meal still digested inside? them, to help understand their natural food?
Following this whim, he dissects a preserved stellar sea creature from Antarctica, but instead of food, he finds new life frozen in time inside the creature’s coelomic cavity. There are about 10 baby sea stars, each an image of their parent, which like many starfish are likely hermaphroditic.
Described by Dr. Mah hatching starfish as a new species, Paralophaster ferax. He published the search, including a plethora of other natural history observations of Antarctic starfish, in the journal Zootaxa in June.
Dr. also describes Mah is a new genus of starfish and 10 additional new species. Starfish are invertebrates of the class Asteroidea, so they’re also known as asteroids (yes, another cosmic name). You have to go back to 1940 to find “the last time a novel brooding species was described from Antarctica,” said Dr. Mah.
P. ferax is unlike most starfish species, which reproduce by shooting their eggs and sperm into the water and leaving their young to fend for themselves. But the habit of holding offspring – brooding – has evolved many times and is especially common in Antarctic waters.
The popularity of parental care in Antarctic asteroids may have something to do with the strength of the currents that flow through their frigid home, said Cintia Fraysse, a starfish biologist at the Austral Center for Scientific Research in Ushuaia, Argentina. “The current is tough, so it’s hard to reach the seafloor to settle as a larva,” said Dr. Fraysse.
Many species also live so deep that sunlight cannot reach the photosynthetic plankton, leaving the larvae with little food to eat. For babies to survive, it makes sense for a parent to raise them until they are old enough to stand on their own.
Although many starfish take care of their young, not all of them use the same parenting techniques. Some, like P. ferax, house their little starlets in a special body cavity; others just put it in their mouths. Others have developed baby-carrier-esque structures between their arms to hold the young. “It’s like a prison in the armpit,” says Dr. Mah.
Although finding the confused babies was a pleasant surprise for Dr. Well, his instinct to see if starfish were caught chewing their food proved fruitful for his original question as well. One specimen, an Antarctic sun star or Solaster regularis, has a smaller, partially digested starfish of the species Anasterias antarcticus in its mouth.
Often mistaken for docile or passive, starfish are in fact voracious predators, says Dr. Fraysse, preyed upon by sea urchins, crabs and, as Dr. Meh, even other starfish. “They control the benthic ecosystem,” said Dr. Fraysse. They “put the stomach out of the mouth” so they can eat things bigger than themselves. One particularly ravenous specimen, kept at the Smithsonian but not used for this study, had the arm of another starfish sticking out of its mouth.
Dr. does not need to travel. Mah in Antarctica to make these discoveries — he just had to work. Most of the deep-sea star specimens were collected in the 1960s by the US Antarctic Research Program. When they ended up at the Smithsonian in 2010, no one paid them any attention. Dr. expects Hopefully his work will shine a light on the importance of good old-fashioned organismic biology.
“Very few people get down to the species level and investigate critters the way humans used to,” he says.
Observing the natural history of animals, whether they are in nature or sitting on a museum shelf, provides the foundation on which the rest of zoology rests. “When we do physiology or reproduction,” said Dr. Fraysse, “this kind of work makes it easier for us.”
