Science Made Cool

Not Dead Yet

Luke Pearce went to the Southern Tablelands of New South Wales to look for an endangered fish. He found a little lagniappe -- a population of the Yellow-spotted Bell Frog, an amphibian  that no one had seen live in the wild since the 1970s. In this footage, they take field measurements of the adult frogs.  

So Cute, It Hurts

Meet Kit, the newest addition to the sea lion exhibit at the Monterey Bay Aquarium. She's currently about 15 weeks old, and cute as a button. A live webcam of her tank is available from 7 am to 7 pm PST.

Friday Parasite: Togetherness

A male and female schistosome worm in all their mated-pair glory. The male is the larger individual; the female can be seen peeking out of his gynacophoric canal -- a ridge along his belly that serves as her home.

SEM photograph by Bruce Wetzel and Harry Schaefer, National Cancer Institute. 

 

Friday Parasite: Entwined Under the Sand

At first glance, you might think the rounded mound sticking out of the sand was a mushroom cap. But look closer – those purple spots are flowers. It’s not a fungus, it’s a plant -- and as you might guess from the complete absence of green leaves, it’s a parasitic one.

 Sandfood (Pholisma sonorae) lives in the sandy deserts of southern California and Arizona. It grows in loose sand near its hosts, which are typically small shrubby desert perennials like arrowweed, burro-weed, or dyebush. The relationship between host and parasite isn’t obvious when you walk by, because the two are attached at the roots.

 A sandfood plant taps into its host’s root system and siphons off sugars and proteins to put toward its own growth. And can they ever grow – at the end of a growing season there can be a fleshy stem as long as a grown man hiding underneath that mushroomy flower. A full-grown sandfood can actually weigh more than its host plant, though a lot of that mass is water. P. sonorae doesn’t need a host for that part – it absorbs water through the modified scaly leaves covering its stem. And it’s possible that sandfood’s ability to store up fluid lets its hosts turn the tables on it during long droughts: sucking water out of the parasite to let them keep photosynthesizing in conditions that make other plants shut down their food factories. If that turns out to be true, it may be fair to ask which plant is actually the parasite. And the answer may be as changeable as the weather. 

Photo © 2008 Michael L. Charters, used with permission 

Source: Arizona Game and Fish Department Heritage Data Management

Friday Parasite: Sharing Dangers With Your Host

Becoming a parasite means that, one way or another, you’ve thrown in your lot with your host. Their food may become your food, their droppings (or flesh) the medium that moves your young to a new home, their habits a template for you to exploit. And an interesting paper published in the Journal of Experimental Biology last year shows that sometimes their dangers become yours, too.

 Ormia ochracea is a small fly that’s a parasitoid of crickets – adults may fly around in the environment, but their larvae have to grow up inside a field cricket. This means that a female Ormia needs to find a living cricket to feed her young. Fortunately for her, crickets advertise.

 Female Ormia exclusively target male crickets as host material. They find them by listening for their song: in fact, they’ve evolved specialized “ears” on their first pair of legs that are sensitive to the  high-pitched cricket song most flies can’t hear. So on a summer night, as a male cricket sings to attract a mate, gravid female Ormia are also flying toward his song. When a fly gets close, she lands, walks until she finds the singing cricket, then deposits larvae on his back and on the ground around him. The maggots burrow into their new host and spend the next 10 days chowing down on the cricket’s interior. When they emerge to pupate, the cricket dies.

Obviously, male crickets are singing to attract female crickets, not female parasitoid flies. But both the female crickets and the female Ormia fly toward the male’s song, and they can both wind up as the victim of the same voracious nocturnal predator: bats. Some bats also use cricket song – in this case to locate their prey. Above one calling male cricket you might find a female cricket flying toward a mate, a female Ormia flying toward a new host, and a bat flying toward a meal. Bats aren’t picky – one plump insect is as good as another – so all the bugs in this scenario are at risk. Tying their life cycle to the crickets, the flies also became vulnerable to their predators.

Flying crickets are known to perform evasive maneuvers when they’re hit by a bat’s sonar pulse, and Merri Rosen and her colleagues at Cornell University wanted to see whether Ormia had evolved a similar behavior. Bear in mind that most flies targeted by a bat would be toast – their ears aren’t sensitive to anything as high-pitched as bat sonar, so they’d never hear the bat coming. But Ormia has those specialized ears for tuning in cricket song: can they also use them to detect bats? And if the flies hear a bat, what do they do about it?

To find out, the researchers tested how the flies behaved when they heard high-pitched sounds, both while they were walking and in flight. They found that when the flies were on the ground, they walked toward any high-pitched sound. The flies clearly could hear the ultra-high batlike pitches just as well as the cricket chirps; they just didn’t seem to distinguish between sounds that meant ‘food for babies’ versus sounds that meant “DANGER!” All that changed when the flies took wing. In the air, the flies were more discriminating -- steering toward the lower-pitched cricketlike sounds, and away from pitches more like bat sonar. It’s a pretty bit of convergent evolution in which fly and cricket, linked by parasitism, exposed to the same danger, evolve similar plans for making a getaway.

Rosen, M., Levin, E., & Hoy, R. (2009). The cost of assuming the life history of a host: acoustic startle in the parasitoid fly Ormia ochracea Journal of Experimental Biology, 212 (24), 4056-4064 DOI: 10.1242/jeb.033183

PHOTO: Ron Hoy's lab: Cornell University

Puzzle-Solving by Birds and Boys

March, 2006: My three year old son sat at one end of a table in the psychology lab, excitedly shaking a tiny green truck sealed inside a Plexiglas tube. The game he was playing was simple: if he could get the truck out of the tube, he got to keep it. He’d already ‘won’ two toys – a small Koosh animal he’d had to push out of the tube with a snug-fitting rod, and a toy bug he’d retrieved from the far end of the table with a rake. But this time the rod was a couple of feet out of reach, and the rake’s handle was too fat to fit inside the tube. After a few minutes of shaking and poking, he grabbed the rake, pulled the rod across the table, and pushed the truck out of the tube. Score three for Robin; another data point for the graduate student running the experiment.

Cognitive scientists think that the ability to use one tool to retrieve another is closely associated with the brain’s ability to reason and plan. Obviously, people can do it -- although the ability doesn’t develop until late in toddlerhood -- but there’s evidence that it isn’t a uniquely human behavior. Placed in a situation where they need to use one tool to reach another in order to retrieve food, some individual gorillas, chimpanzees, orangutans, and capuchin monkeys solve the “two tool” problem without coaching. And more recent research suggests that some birds are in on the act, too. Take a look at this video from the University of Oxford, in which a New Caledonian crow (Corvus moneduloides) named Betty chooses not two, but three tools in a row –successively using a shorter stick to pull out a longer stick until she gets one that’s long enough to reach her treat. 

Here Comes Science Concert plug

A contingent of Zygotes just got back from seeing They Might Be Giants in concert; the band is promoting their new kids album, Here Comes Science. The show was fun and included this number, which is near and dear to our bone-digging hearts:

Peeved About Panda Reporting

 Earlier this month, Nature released a paper describing the major results of the Chinese Panda Genome Project: a draft sequence covering 94% of the bear’s genome. Thanks to the “cuddly” factor – who doesn’t love the cute fluffy pandas? ­­-- the paper got a fair bit of press. And almost all of those articles focused on bits of the panda genome that seemed a little surprising: that pandas can’t make enzymes for digesting cellulose even though they eat nothing but bamboo, that they can make enzymes for digesting meat and fat despite their vegetarian diet, and that that they can’t taste meat thanks to a mutation that knocked out the unami receptors on their tongues.

There’s just one problem: those things might be surprising if you just think of a panda as a weird bear with a grass-eating habit, but they actually make a lot of sense when you pull back and look at pandas in the context of their evolutionary history. The place where pandas sit on their family tree lets you predict what you might find in their genes. And in this case, those predictions would be confirmed. Let’s look at those ‘surprising results’ again below the fold:

Why Didn't I Ever Think of Making Cookies Like These?

I bake a lot. But most of my creations, although I've had people rave about the way they taste, aren't going to win any beauty contests. Ginger crinkles? Round and brown. English-style gingerbread? Square and brown. Grandfather's rugelach? Light brown and blobby. So I'm consumed with envy by the science cookie creations over at Not So Humble Pie. Fruit flies, lab mice, gingerbread microbiologists, and beautiful sparkly zebrafish are just a small sampling of what Ms. Humble does with cookie dough and royal frosting. That woman wields a mean icing tube. 

I know I'm too much of a klutz to even attempt most of these designs, but maybe I can manage a simple batch of petri dishes this holiday. (Aren't they awesome?)

Water Birth

Welcome a 162 pound, 5-foot-4-inch baby boy, born on Monday to Puiji, a beluga whale at the Shedd Aquarium in Chicago. He was a breech birth (that’s head-first, for a whale), but popped right to the surface for his first breath anyway. He got the hang of surfacing to breathe pretty quickly, but his swimming still needs work. As a rule, baby cetaceans are pretty floppy creatures (their bodies have to fold in half to fit inside the uterus – see the image below from Etnier, et al. 2008), but his tail should stiffen up in a few weeks and make him a far more efficient swimmer. 

Reference: Etnier, S. A., W. A. McLellan, J. Blum and D. A. Pabst 2008. Ontogenetic changes in the structural stiffness of the tailstock of bottlenose dolphins (Tursiops truncatus). J. exp. Biol. 211: 3205-3213.