The bodies of the crabs displayed male reproductive structures, while other parts showcased female features, including gonopores, said K.S. Anoop Das.
In a recent study published in the zoology journal Crustaceana, scientists working in Silent Valley National Park reported a new variety of the crab that exhibits both male and female traits. Our new crab friends, of the species Vela carli, are freshwater dwellers that hang out in the streams of the Western Ghats in India.
The animals do, however, have neuronsnerve cells that appear interconnected throughout their body. And now a new study shows that how these animals sleep is surprisingly similar to humans, suggesting that sleep may have evolved before even the most primitive brains. The findings, published on Tuesday in Nature Communications, also help answer one of science's prevailing mysteries: Why do animals sleep?
Neither jellyfish nor sea anemones have brains. But these animals sleep in ways strikingly similar to humans, according to a study published today in Nature Communications. The findings bolster a theory that sleep evolved, at least in part, to protect the DNA in individual nerve cells, helping to repair damage that builds up while animals are awake.
Which animals came first? For more than a century, most evidence suggested that sponges, immobile filter-feeders that lack muscles, neurons and other specialized tissues, were the first animal lineages to emerge. Then, in 2008, a genomic study pointed to a head-scratching rival: dazzling, translucent predators called comb jellies, or ctenophores, with nerves, muscles and other sophisticated features. That single study ignited a debate that has raged for nearly 20 years, sparking fierce arguments about how complexity evolved in animals.
But as he swept his flashlight through the dark waters, something unexpected emerged. Inching through the beam of light, an alien creature crawled across the surface of the sand, resembling an inch-long cluster of ghostly leaves fringed with silvery filigree and capped with a pair of antennae-like stalks. It immediately caught my eye, said Gosliner, Invertebrate Zoology Curator for the California Academy of Sciences. I've been diving there for 30 years and this one immediately struck me as different.
Wooden objects carrying the marks of carving and use could be the oldest wooden tools ever found. Researchers dated the artefacts, found in what is now Greece, to 430,000 years ago - and suggest they might have been made by early Neanderthals or their ancestors, Homo heidelbergensis. A separate study describes 480,000-old flint-knapping tools made from antler and elephant bone, from what is now the United Kingdom.
It looked like the silvery blade of a knife. Peering through his goggles, diver Ted Judah had laid eyes on a deep-sea creature rarely encountered by humans. He and wife Linda were diving off McAbee Beach in Monterey County in late December when, near the surface, he spotted the undulating thing. It was some kind of ribbon fish, he wrote in a post on the Facebook group Monterey County Dive Reports. Kevin Lewand solved the mystery.