When bloodhounds lose the scent of an escaped convict at the water's edge, it may be time to unleash the water shrews. A Vanderbilt University biologist has discovered that the shrews, and at least one other water-loving mammal, can follow scents underwater.
Until now, the notion that mammals could take a subsurface sniff was dismissed because they can't breathe underwater. But biologist Kenneth Catania was puzzled. High-speed video showed that water shrews and star-nosed moles put their noses close to the bottom as they foraged. The animals exhaled air bubbles, which grew to touch the bottom, and then quickly inhaled them at a pace similar to a rat's sniffing.
Dr. Catania set up food-scented underwater "trails" to test the idea. When he allowed the animals to get close enough to the trails at the bottom, they followed them to the food 85 to 100 percent of the time. When a metal mesh kept them too far above the trail for the bubbles to touch it, or when they had no trail to follow, the animals' success rate was no better than chance.
"This came as a total surprise, because common wisdom is that mammals can't smell underwater," Catania notes. The results appear in the current issue of the journal Nature.
Scientists in Europe have uncovered the fossil remains of a giant, plant-eating dinosaur some 150 million years old. They say the remains represent the most primitive type of large plant eater, or sauropod, yet found from this period. The fossil remains come from a creature thought to have weighed from 40 to 48 tons. It stretched between 98 and 124 feet from the tip of the nose to the tip of the tail.