Humpback Whales May Be Migratory Astronomers

An eight-year project that tracked humpback whale migrations by satellite shows the huge mammals follow uncannily straight paths for weeks at a time.

The results suggest a single migratory mechanism isn’t responsible. Instead, humpbacks may use a combination of the sun’s position, Earth’s magnetism and even star maps to guide their 10,000-mile journeys.

According to scientists, they are going across some of most turbulent waters in the world, yet they keep going straight.  They’re orienting with something outside of themselves, not something internal.

Humpback whales feed during the summer near polar oceans and migrate to warm tropical oceans for the winter, where they mate and calves are born. A one-way trip can last upwards of 5,000 miles, making the cetaceans the farthest-migrating animal on Earth. (One was tracked migrating 6,200 miles).

To better understand humpback migrations, scientists embedded satellite tags in seven South Atlantic and nine South Pacific whales from 2003 through 2010.  The researchers found that, despite surface currents, storms and other distractions, the humpbacks never deviated more than about 5 degrees from their migratory courses.  In about half the segments mapped by the researchers, humpbacks deviated by one degree or less.

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Orangutans Use Simple Tools to Catch Fish

Orangutans swim about as well as they fly, but research on three Indonesian islands shows that these long-limbed apes nonetheless catch and eat fish.

Orangutans living in Borneo scavenge fish that wash up along the shore and scoop catfish out of small ponds for fresh meals.  Over two years, scientists saw several animals on these forested islands learn on their own to jab at catfish with sticks, so that the panicked prey would flop out of ponds and into a red ape’s waiting hands.

Although orangutans usually fished alone, scientists observed pairs of apes catching catfish on a few occasions. In one case, an orangutan cringed and pulled away as its companion extracted a fish from a pond. Scientists suspect that the onlooker was learning — or at least trying to learn — how to nab aquatic snacks.

Observations of fishing by orangutans raise the likelihood that hominids ate meat, including fish, before the emergence of the Homo genus around 2.5 million years ago. Anthropologists have traditionally held that meat-eating first assumed prominence among early Homo species and fueled brain expansion.

Fishing isn’t common among primates, but it does occur. Chimpanzees occasionally pluck fish out of ponds. Some monkeys that swim well, including certain macaque and baboon species, also catch fish with their hands.

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Salamander Has Algae Living Inside Its Cells

In a symbiotic union more complete than any previously found in vertebrates, the common spotted salamander lives with algae inside its cells.

Such a degree of cross-species fusion was long thought to exist only among invertebrates, whose immune systems are not primed to destroy invaders. But algae live inside the salamanders from before birth, possibly passed down from parent to offspring.

That spotted salamanders and algae live in symbiosis was first noted in the 19th century, and in the 20th century researchers worked out the relationship’s mutual benefits. Salamander eggs provide a nitrogen-rich environment for algae to grow; algae oxygenate the embryos, which develop deformities without them.

But algae were believed to float outside the embryo itself, in the egg’s nutrient broth.  Now scientists have noted that algae’s distinctive green glow didn’t just emanate from eggs, but from inside embryos.

Algae invade spotted salamander embryos early in their development, when individuals are just beginning to take shape inside their eggs, as the brain folds up and tissue layers-to-be first organize themselves. As an embryo develops, algae suffuses its body, but most becomes concentrated along its gut and alimentary canal.

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Poisonous Frogs are More Fit

After testing hundreds of frogs representing dozens of species on an amphibian version of a treadmill, researchers have determined that colorful, highly poisonous frogs have the greatest aerobic capacities.

Earlier studies had suggested a link between poison and metabolism in frogs, but involved just a handful species.

In frogs, especially bright colors generally signify toxicity, informing predators of their prospective meal’s unpalatability. But whereas most poisonous animals produce venom naturally, the frogs distill it from their food.

To find the right insects, they forage far and wide, rather than waiting for whatever fare passes by. Evolution would seem to have produced aerobic adaptations that help poisonous frogs roam, then amplified coloration as a defensive signal.

It’s also possible that bright coloration evolved first, providing some sort of advantage — predator defense, perhaps, or help finding mates — that allowed those frogs to range farther than their drab brethren. That in turn could have allowed them to specialize in eating uncommon, toxin-enabling insects.

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