After a Valentine’s Day rendezvous, seeing stars, sperm and millions of spawn
News and notes about science
On Valentine’s Day, Melissa Torres strung up red tinsel hearts around a shallow pool at her workplace, the Birch Aquarium at Scripps Institution of Oceanography in La Jolla, Calif. She and her colleagues were arranging a romantic encounter of sorts. The happy couple, a pair of sunflower sea stars, belonged to a species that has nearly vanished because of climate change.
Sunflower sea stars are a far cry from their smaller pink cousins that you might know from “Finding Nemo.” They have up to 24 arms and can grow to diameters of more than 3 feet. They also prey upon sea urchins living among the stalks of algae that make up the kelp forests of the Pacific Northwest.
Without climate change, the sea stars might be keeping the kelp forest ecology in balance. But in 2013, a 1,000-mile-wide mass of warm water nicknamed the Blob formed in the North Pacific. As a consequence of the heat, a strange wasting condition began spreading among the sunflower sea star population. Since then, an estimated 90% of all sunflower sea stars have perished.
Torres injected a male and a female with an enzyme that caused them to release eggs and sperm. Then she and her colleagues waited — two hours for the male, and four hours for the female. Once both animals had successfully spawned, “we were jumping and screaming and hugging each other and freaking out,” she said.
— Kate Golembiewski
A fern’s ‘zombie’ fronds sprout unusual roots
In western Panama, University of Illinois plant biologist Jim Dalling stumbled upon some tree ferns with 6-foot-long leaves that bent to the ground as they were dying, encircling the plant like a skirt. The leaf remnants were brown and withered — dead, it appeared (though still attached to the tree fern’s trunk). How, he wondered, could lifeless plant matter be endowed with roots?
Further study showed that this tree fern, known as Cyathea rojasiana, transforms the inner part of its dead or dying leaves.
The remnants of the xylem and phloem — tubules that transport water, sugars and nutrients throughout living leaves — somehow become a root. The tips of these fronds, nicknamed “zombie leaves,” then sprout new fine roots, said Dalling, co-author of a recently published study on the plants.
While transmuting the midrib of the leaf, the plant undergoes a proliferation of new vascular tissue — and avoids rotting while the rest of the leaf withers away.
— Douglas Main
Claim disputes ancient whale was heaviest animal ever
Last August, a team of paleontologists announced that they had discovered the fossilized bones of a gigantic ancient whale. Perucetus, as they named it, might have weighed more than 200 tons, which would make it the heaviest animal that has ever lived.
But in a new study, scientists have challenged that bold claim. In their new analysis, Nicholas Pyenson, a paleontologist at the Smithsonian, and Ryosuke Motani, a paleontologist at the University of California, Davis, concluded that Perucetus probably weighed 60 to 70 tons, about the size of a modern sperm whale.
They also analyzed fossils of blue whales and provided a new estimate of the weight of that species. They concluded that blue whales weigh up to 270 tons — much more than previous estimates — which would easily make them the heaviest known species in the history of the animal kingdom.
Perucetus came to light in 2010, when Mario Urbina, a paleontologist in Peru, spotted a bone in a Peruvian desert. He and his colleagues excavated 13 vertebrae, four ribs and part of a pelvis.
The bones had many hallmarks of whales’ bones. But they were also astonishingly large and heavy. Urbina and his colleagues reconstructed the full skeleton of Perucetus by studying the much smaller whales that lived at the same time. They also drew inspiration from living manatees, which have dense skeletons that let them stay underwater to graze on seagrass.
Motani and Pyenson both felt that modeling Perucetus after manatees was a mistake, since only whales have evolved to truly gigantic sizes. They created a 3D model of the blue whale, and used it to make a model of Perucetus. With this approach, they estimated that Perucetus weighed 60 to 70 tons, much less than the other research team had concluded.
— Carl Zimmer