The Smallest Vertebrate to the Largest

• The world’s smallest vertebrate (animal with a backbone) is a tiny frog recently discovered in an eastern New Guinea rainforest. Three of them could rest comfortably on a dime, for their average size is about 7 millimeters in length. This cute little frog lives in rainforest leaf litter, and probably dines on springtails, mites, and ticks. An Indonesian fish related to carp held the previous “smallest vertebrate” record; the female measures about 7.9 millimeters in length. (Science, Jan. 20, 2012)

• Science has also turned its attention from the smallest vertebrate to the largest – the blue whale. These giants feed on krill – small, shrimp-like creatures that flourish in the ocean. Blue whales are lunge feeders, and when one encounters a swarm of krill, it rapidly lunges into the swarm with its mouth wide open and then slams its jaws shut. In the process the whale traps in its mouth an amount of water and krill that weigh more than the whale itself, and the throat region expands to accommodate the huge load of water. The mass of water is quickly pushed out through thin baleen plates in the mouth, but the krill are trapped and swallowed. An average blue whale weighs about 147 tons, and the amount of water ingested in a lunge weighs over 150 tons; the whale is almost stopped in its tracks by this amount of weight in its mouth. (Science, Jan. 20, 2012; research at the Cascadia Research Collective in Olympia, WA)

• The importance of exercise to your well-being cannot be overemphasized. A recent study in Taiwan reported that moderate activity, such as a half-hour walk five days a week, increased the life expectancy of men in the study by four or more years. Women’s life expectancy with moderate activity increased by more than three and a half years.

Until recently, scientists didn’t know much about why exercise made such a difference. This year researchers at the University of Texas Southwestern Medical School provided direct evidence that increased exercise enhances the ability of cells to digest parts of themselves that have broken down and no longer function in an efficient manner. The process is called “autophagy,” which literally means “self-eating.” It is known that some of the sausage-shaped energy factories inside cells, called mitochondria, wear out and are digested. These worn out mitochondria lose their ability to inactivate free radicals (by-products of energy production). Since mitochondria can replicate themselves, the ones that are eliminated by autophagy are replaced. The new mitochondria are better able to inactivate the free radicals they produce. This means that if you exercise, your chances of living longer are enhanced because worn-out mitochondria are disposed of in an efficient manner, and the accumulation of excess free radicals in cells is diminished. (The Economist, Jan. 21, 2012; Consumer Reports On Health, Feb. 2012; Levine, et al, Nature, Jan. 20, 2011)

• Hissing cockroaches are no big deal to a biologist, but whistling caterpillars are new to the nature scene. The walnut sphinx caterpillar (Amorpha juglandis) has the ability to throw back its head and force air through tiny holes in its sides, producing a high-pitched whistle. When certain prey birds hear this whistle, they are startled and fly off. As if this weren’t enough, the caterpillar also avoids some predators by flicking poop at them. (ScienceNOW, Dec. 10, 2010; based on article published in The Journal of Experimental Biology)