Burbot: the lobster of Interior Alaska

Although I spent much of the first eighteen summers of my life floating on Alaskan rivers, I didn’t know about burbot until my partner, our dog, our housemate, and I drove to a trash-ridden bank of the Tanana River last fall. As always, the water looked brown and uninviting under a nondescript gray sky. The muddy islands between the river braids were sloughing off with soft plops. This is where the ugly, yet delicious, tender-fleshed burbot live.

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Tanana River near the Richardson Highway, Alaska. PC Don Angle Photography.

Even the Alaska Department of Fish & Game admits that burbot (Lota lota) are not the most attractive fish. Burbot are distinguished by their mottled green-black-and-yellow skin (which is incredibly slippery and slimy), elongated dorsal and anal fins, and a small chin barb. Notably, they are the world’s only freshwater cod. Mature burbot can have extremely large heads with huge gaping mouths and a protuberant stomach. Unusually, burbot spawn in the winter, under the ice, and do so in a large, writhing ball.

IMG_8517Furry meets slimy: Junie with a burbot caught on a tip-up at George Lake.

We had come to the Tanana equipped with 15 set lines. Sturdy birch branches had been cut and chiseled to a point at one end. The other end was an attachment point for a long fishing line with a weight and a baited hook. We each set out with five set lines to place along the disintegrating banks. Once the pointy ends were securely jammed in the mud, we tossed out our lines spiraling with weights into the silty water. The lines were left out overnight (our experience has been that burbot are particularly active and more prone to munch at night) and checked the following afternoon.

It’s fun to check the lines. You slowly start pulling, reeling in one hand over the other, and right away you can feel that there is something weighing down your line. It’s particularly exciting if that something feels particularly heavy. As I’ve only fished for burbot in murky rivers, you can’t see what’s on the end until it’s exited the water, so you are left to your imagination until the fishy monster is on the shore.

We may have caught one or two that first go-around on the Tanana; memory does not serve me well here. Subsequent fishing trips (the Ray River off the Yukon, George Lake off the Richardson Highway) have yielded several nice, fat burbot.

Burbot flesh is advertised as being lobster-like, tender and delicious, great with butter. I can attest that these descriptions are quite true, and marvel that such delicious meat comes from such a slimy beast.

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Butterfly ears

When I really think about it, I suppose it isn’t too surprising that butterflies have ears. But what may be news even to butterfly aficionados is that the mysterious swollen wing vein in the subfamily Satyrinae actually helps these butterflies detect low-frequency sounds.

Sun et al. recently published an article in Biology Letters about their work identifying the function of these conspicuous forewing vein swellings. Using the common wood nymph (Cercyonis pegala) as a model, the researchers took some beautiful photos of the ear, the forewing vein, and the opening connecting the tympanal chamber (e.g. the ear canal) to the vein.

Ear and wing vein morphology of C. pegala. (a) Butterfly in resting position. A white circle marks the location of the ear. Scale bar: 5 mm. (b) Light micrograph of right tympanal membrane. Scale bar: 200 µm. (c) Forewing showing enlarged subcostal (Sc) vein, as well as cubital (Cu) and anal (An) veins. Tympanal ear is seen at the wing base. Scale bar: 1 mm. (d) Internal structure of Sc vein viewed through the cuticle. Scale bar: 500 µm. (e) Cross-section of the Sc vein. Scale bar: 500 µm. (f) Laser scan of Sc vein and tympanal membrane depicting displacement at 4.8 kHz. Inset: Scanning electron micrograph of the opening connecting the tympanal chamber and Sc vein. Scale bar of inset: 100 µm. Figure and caption from Sun et al. (2018).

After capturing images of the ear and puffy vein, they tested the mechanical response of the ear. C. pegala ears appeared to be most sensitive to low-frequency sounds, and when the special veins were ablated (cut open longitudinally) the ear showed reduced sensitivity.

What do butterflies hear? The authors suggest that they can detect sounds like bird flight and calls. More broadly, insects also use their ears (and other hearing organs) to locate mates and coordinate social interactions.

Want to read the entire (short) study? You can find it here.

To freeze or not to freeze: insect overwintering strategies

Perhaps winter hasn’t quite yet crawled up your windowpanes or stretched its fingers across your favorite pond, but it’s certainly making its presence known at latitude 64°N. I’ve been pulling out extra quilts, wrapping up in scarves for my morning bike commute, and making more baked goods to keep up with my hot chocolate habit.

As a graduate student, I study the molecular story behind arctic ground squirrel hibernation at the University of Alaska Fairbanks. I’m the first to admit I’m a mammal kind of gal⎯I gravitate towards the furry and fuzzy and revel in soft fur, large eyes, and squeaky-cute chirps. However, every now and then I step outside of my mammalian bias and remember that there is a world of tiny, crawling, wiggling creatures that are surviving the cold in ways that are equally as extraordinary as the strategies employed by my favorite hibernating rodent.

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Arctic ground squirrel hibernating in the lab. So cute. Copyright © 2013 Øivind Tøien/Institute of Arctic Biology.

I don’t think I’m alone in my mammalian predisposition. It can be easy to overlook insects, especially the more inconspicuous and less flashy species. However, during the Alaskan spring and summer, it is impossible to ignore the state’s most infamous insect: the mosquito.

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Mosquito (Culex quinquefasciatus) larva. Image courtesy of the CDC.

Growing up in Alaska, I never thought about what happened to mosquitoes during the winter. Perhaps I was simply happy they were gone, or maybe my gravitation towards the furry was present from a tender age. In any case, it wasn’t until I was in my late twenties that I learned there are two general types of Alaskan mosquitoes. One variety⎯affectionately called “snow mosquitoes”⎯overwinter in adult form. When temperatures start to drop, they tuck away in tree bark or bury themselves in the leaf litter and begin the process of supercooling.

You may have heard of supercooling, the process by which a liquid can remain liquid below its usual freezing point. A supercooled liquid must remain completely free of any impurity, as even a speck of dust can serve as a nucleation point for ice crystals to form. After snow mosquitoes rid their blood of impurities, they are able to survive winter temperatures as low as -31°C.

The adults of the other variety of mosquito lay their eggs in the fall. After depositing the next generation of blood-sucking babes, the adults do not attempt to make it through the chilly winter ahead and die an unmourned death. Their progeny hatch in the spring and are considered much more voracious biters than their cousins. (Interested in mosquito matters? Refer to the seminal 1949 book The Natural History of Mosquitoes by Marston Bates.)

(Quick mammalian aside: Arctic ground squirrels are the only known mammal to supercool. Similar to mosquitoes, they are also thought to remove their blood of impurities that would otherwise encourage ice growth. Arctic ground squirrels can lower their body temperature to -2.9°C, an incredible feat for an endotherm.)

Supercooling is an example of a freeze-avoidant strategy, in which an animal shifts its physiology to avoid the buildup of ice crystals in its blood. Yellowjacket queens living in subarctic Alaska also supercool. To avoid touching snow or ice, which can disturb a supercooled insect and promote instantaneous freezing, the queens hang by their mandibles from a twig or leaf stem in the leaf litter. The hollow space occupied by their hanging body creates a buffer of air between them and any dangerous frozen water.

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Vespula vulgaris, or common wasp, or yellowjacket. Image courtesy of JL Boyer.

Another equally impressive strategy employed by overwintering insects is freeze tolerance. Instead of preventing the formation of internal ice, these insects embrace it. There are various means of becoming an insect icicle, and most involve promoting crystallization extracellularly. Encouraging ice to form outside of cells protects the delicate machinery within cells, which carries clear benefits to the animal. One exception to this rule is found in the alpine cockroach (Celatoblatta quinquemaculata), which can survive temperatures down to -9°C and allows for the formation of ice crystals within its gut cells. It isn’t entirely clear how they achieve this feat, but it could be via thermal hysteresis proteins (also known as antifreeze proteins). These proteins widen the gap between water’s melting point and freezing point by shaping ice into protein-sheathed, faceted ice crystals. Employing a thermal hysteresis strategy decreases the insect’s lower lethal temperature. Other freeze-tolerant insects include the Isabella tiger moth (Pyrrharctia isabella) and the flightless midge (Belgica antarctica).

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The mechanism of thermal hysteresis via antifreeze proteins. Figure courtesy of Davies 2014.

It’s incredible to think about anything staying warm during a Fairbanks winter, much less a tiny mosquito or a wee wasp queen. To maintain my own endothermic heat through Alaska’s longest season, I use a variety of items and strategies, including down jackets, mittens, extra socks, toe warmers, heating oil, gasoline, wood stoves, hot chocolate, soup, quilts, and dog snuggles. Not nearly as efficient as some of my insect friends, but they will have to do.

Sister species interactions in birds, and the potential for citizen science to change our perspectives

Every day, birders around the world record which species they see. Many of them contribute their sightings to the groundbreaking citizen science project called eBird, run out of the Cornell Lab of Ornithology in the US. One outcome from this collective activity is a worldwide record of which species have been reported in the same place at the same time – i.e. which species come into contact.

This citizen science has potential to really change the way we work at bird interactions.

Read about it here!

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T. Rex couldn’t stick out its tongue

Dinosaurs are often depicted as fierce creatures, baring their teeth, with tongues wildly stretching from their mouths like giant, deranged lizards. But new research reveals a major problem with this classic image: Dinosaurs couldn’t stick out their tongues like lizards. Instead, their tongues were probably rooted to the bottoms of their mouths in a manner akin to alligators.

Read more at: https://phys.org/news/2018-06-rex-couldnt-tongue.html#jCp

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The giant salamander might be a pyramid scheme

The world’s largest amphibian should be easy to find. The Chinese giant salamander can be as big as your entire body, and on average resemble a labrador. And while they used to be abundant, after months of searching, scientist are struggling to find even a few. 24 individuals, across 50 sites where the salamanders once thrived. Moreover, the few found all have genetic markers indicating they had escaped or been released from farms. There may not be any wild individuals left.

But this tragedy is getting worse. Based on analyses of the salamander, it’s becoming clear that it’s not one species but five. And they are all facing imminent extinction in the wild.

Read more about it here.

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The Synchronized Swimming of Sea Monkeys

Tiny crustaceans complete a massive daily vertical migration in the world’s oceans. New research suggests their commute may play an important role in the health of the planet.

Dr. Dabiri, an engineering professor at Stanford University, suspected there was more than could be seen by the naked eye in the movements of these small marine creatures. And in a paper published in Nature, he offered evidence that they are capable of playing a vital role in mixing up the many layers of the oceans and the minerals they contain.

Want to know more about this vital dance? Read about it here.

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