October 2019 - Favorite World Press

The FWP weekly digest of wondrous wildlife happenings
and other interesting items from the natural world

Creatures to meet | Things to learn
Things to do

Lisa S. French

Compared to many of the creatures featured on Weekly Wondrous, the electric eel (Electrophorus electricus) scores relatively low on the cuddlesome quotient, however, what the high-voltage South American river dweller lacks in animal magnetism, it makes up for in shock value. And the most shocking eel of them all, the new species Electrophorus voltai, was discovered this fall by scientists at Smithsonian’s National Museum of Natural History.

But before we get to that electrifying story, perhaps you are wondering, “What are eels, anyway? Reptiles? Amphibians? Fish? Amphishians?” Strictly speaking, electric eels are not true eels but a species of electric fish—long, blade-shaped knifefish to be exact, and more closely related to carp and catfish than eels. The 800-plus species of true eels primarily live in saltwater, while electric eels can only be found in the murky freshwater habitats of the Amazon and Orinoco Rivers. It was there, in the highland waters of the Brazilian Shield, that the approximately 8-foot long, 860-volt-producing Electrophorus voltai was identified—the strongest living bioelectricity generator known to date. To put that impressive eel power into perspective, the human body is only capable of producing and transmitting between 10 and 100 millionths of one volt over a distance of approximately one-millionth of a meter, a fact for which those of us who travel by crowded subway are quite grateful.

Like all species of electric eels, the E. voltai produces its record-breaking current through the stimulation of thousands of synchronized stacked cells called electrocytes in three pairs of electric organs that take up 80% of the length of its body. The Smithsonian researchers theorize that the 30% increase in electricity-generating potential from the highest previously recorded E. electricus measurement of 650 volts may be an adaptation to the reduced conductivity of the waters where the E. voltai species began its evolution about 7.1 million years ago.

Electric eels make full use of their innate ability to self-generate jolts, utilizing their piscine electro-pulses for eel-to-eel communication, navigation, self-defense, and to locate and stun small fish and invertebrate prey. The objects of the carnivorous fish’s shocking attentions are captured through a highly effective two-step strategy, which researchers at Vanderbilt University have compared to a type of remote control. First, the eel transmits an electric pulse, which causes whole-body contractions in its prey, revealing its location, then a second shock is administered to immobilize the target for ease of swallowing.

In case you are curious as to how eels manage to avoid electrocuting themselves when they get down to their meal-zapping business, one hypothesis is that the amount of the electricity flow is small in proportion to the eel’s body but significant to the size of its prey, and of very short duration (about two milliseconds). In addition, a large percentage of the current dissipates into the water, further reducing its impact on the eel’s critical organs.

Studying and understanding how eels generate and transmit electricity has inspired all manner of technological and medical innovations that benefit humankind, ranging from the first electric battery in 1799 to the ongoing development of soft robots, cardiac pacemakers, and artificial organs. While an effort has been made to determine what it would take to run a Tesla Model 3 on eel power for one hour, the estimated requirement of 7,200 eels in 144,000 gallons of water indicates that particular research endeavor to be a non-starter for both the Tesla and the eels.

Two hundred and fifty years after the discovery of the first electric eel species in South America, the recent identification of the E. voltai in the same region is yet another compelling testament to the extreme importance of protecting and maintaining biodiversity hotspots like the Amazon. Given that approximately 85% of our planet’s flora and fauna remain to be discovered, it’s clear that preserving wild spaces is critical to the continued study of the living world. As biologist and naturalist E.O. Wilson writes in The Diversity of Species, “We should preserve every scrap of biodiversity as priceless while we learn to use it and come to understand what it means to humanity.”

Full disclosure: While eels are clearly some of the most remarkable creatures on Earth and can be strikingly beautiful, we empathize if you are somewhat eel-averse as we confess to hyperventilating a bit while researching this one. However, since getting fish-zapped outside of the Amazon is a low probability event, we can rest easy and simply file these slippery fellows under “admire from afar.”

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Lisa S. French October 31, 2019

Kelp Keepers

Widely admired for its conspicuous cuteness, the sea otter is proving to be far more than just another appealingly furry face. Research into this keystone species’ role in maintaining carbon-storing macroalgae, commonly known as kelp, indicates that the bewhiskered marine mammals may be important allies in the battle against climate change. One of 13 otter species, and the largest member of the weasel family, sea otters can be found floating about in coastal waters in the United States, Canada, Mexico, Japan, and the Russian Federation. As their name suggests, sea otters spend the majority of their lives in the ocean, preferring to feed, sleep, and raise their pups in close proximity to kelp, which they use as cover from predators and to anchor themselves and their young when resting.

Equivalent to an underwater rainforest, densely layered kelps are an integral component of healthy marine ecosystems, providing food and shelter for myriad species including fish, shellfish, seabirds, harbor seals, and sea lions. In addition to functioning as critical habitat, recent analysis suggests that kelp forests also have immense potential for permanently storing large amounts of carbon dioxide—up to a whopping 634 million tons per year, an amount greater than the annual emissions of Australia.

One of the reasons that kelp is an especially effective sequester of carbon is because it grows quite rapidly, as much as two feet per day, attaching to undersea rocks with root-like structures called holdfasts. Unfortunately, kelp’s natural nemesis, the sea urchin, is particularly fond of feasting on holdfasts, causing the macroalgae to detach from rock surfaces, drift, and die. Left unchecked, the spiny invertebrates can form hungry herds large enough to decimate undersea forests. And that’s where the sea otter comes in—alongside crabs, mussels, and clams, sea urchins happen to be a favorite food of the voracious shellfishionados. By keeping sea urchin populations under control, otters help to ensure kelp’s survival. Researchers at the University of California, Santa Cruz have estimated that the presence of otters in a coastal habitat increased the sequestration capacity of kelp forests by 4.4 to 8.7 megatons—and they support this valuable ecosystem service every day, absolutely free of charge—give or take a sea urchin or two.

When sea otters were hunted for their fur to near extinction in the 18th and 19th centuries, coastal kelp forests and many of the creatures that relied upon them for survival all but vanished. Effectively eliminating the sea otter from its ecological niche had profoundly detrimental cascade effects on other species in its marine community. Although still currently classified as endangered, over the past century, as a result of dedicated conservation efforts, Pacific otter populations have rebounded from a low of several thousand to approximately 148,000 across Canada, Alaska, Washington, and California. And, as the kelp keepers have returned to their historic range, so have the undersea forests and their inhabitants.

As our knowledge of the interdependence of living things continues to evolve, and we learn more about how mutually beneficial relationships between species like sea otters and kelp can help to maintain biodiversity and contribute to ecosystem services such as carbon sequestration, history serves to remind us that in nature, as in life, sometimes you don’t know what you’ve got until it’s gone.

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Lisa S. French October 16, 2019

Tree-Planting Tapirs

If the Brazilian tapir’s eye-catching ensemble of creature features brings to mind ancient beasts, that’s because the shy, primarily nocturnal South American megafauna is one of the oldest species of large mammal remaining on Earth. The origins of this floppy-nosed, bristly-maned, odd-toed ungulate date back approximately 35 million years. For the ungulate-uninitiated, tapirs are Perissodactyls, hooved herbivores who like their closest relatives horses and rhinoceros, possess an odd number of toes. The Brazilian, or lowland, tapir is one of four widely recognized species of tapir native to the forests, grasslands, and mountains of Central and South America and Southeast Asia.

Measuring five to eight feet long and weighing between 300 and 700 pounds, the Brazilian tapir maintains its impressive bulk by consuming up to an equally impressive 85 pounds worth of shoots, leaves, branches, and fruit a day. As it turns out, the tapir’s hearty appetite for seed-bearing plants plays an important role in restoring degraded rainforests. According to researchers at Ohio State University, 80 percent of trees in the Amazon are dependent upon animals for seed dispersal. One of the primary “gardeners of the rainforest” tapirs ingest and expel a large variety of seeds that have future tree potential. Results of a recent study carried out by scientists at the Amazon Environmental Research Institute in Mato Grosso, Brazil, found that 99 percent of 130,000 seeds passed through a tapir’s digestive systems intact. Seeds that survive the digestive process are more likely to germinate. And here’s where it gets more ‘oh, wow’ interesting: the Mato Grosso study suggests that tapirs may prefer to browse and graze in degraded plots of land rather than in unspoiled forest. When sunlight hits the earth as a result of tree canopy loss in burnt or degraded areas, it forces up and reveals tender green shoots from the forest floor that are attractive to tapirs. The tapirs observed in the study spent about twice as much time feeding in degraded plots resulting in more seed “deposits” in areas in need of reforestation.

In the Amazon, wildlife depend upon healthy forest systems, and as the Ohio State and Mato Grosso research indicates, healthy forest systems depend upon wildlife. The Brazilian tapir’s natural capacity to contribute to tree planting can be an important factor in helping to regenerate carbon-storing, rainforest habitat. That is why protecting an umbrella species like the tapir also serves to protect other animals in its ecosystem.

Despite their aptitude for seed dispersal, Brazilian tapirs alone can’t compensate for elevated rates of Amazon deforestation. In addition, as a result of rapid habitat loss due to wildfires and ongoing land-use change, as well as illegal hunting, populations of Brazilian tapirs are decreasing and currently listed as vulnerable by the IUCN. The good news is you can help keep the hooved horticulturalists of Central and South America in their gardening groove by supporting the tapir research of Nai Conservation and the conservation action plans of the Tapir Specialist Group.

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Lisa S. French October 2, 2019