No, it's not a tribute band. The quirky Icelandic musician Björk has a new album out, called Biophilia. Appropriately enough, the tracks are inspired by themes of nature and biology.
One of the songs in particular, "Virus", was written after Björk learned about "zombie snails" on YouTube. It has nothing to do with real viruses, though (Disclaimer: I haven't heard the album yet so I can't say if the music is any good). These snails are parasitized by a trematode worm called Leucochloridium paradoxum, which you can see in the photo below.
Snail infected with Leucochloridium paradoxum in its eyestalk.
Look closely at the eyestalk on the right. Yup, that's filled with worm. But it's not just one worm. It's a structure called the brood-sac, which contains hundreds of cercariae – little larval worms ("trematode life cycle" on Wikipedia. The sac is banded and green and pulsates. This attracts the attention of birds, which think that it's actually their favorite food, maggots or caterpillars. They swoop in and peck off an eyestalk with all the worms in them. The worms end up in the gut of the bird, and are carried in there to be pooped out somewhere else. Free transportation! Snails grazing along eat some bird poop with the parasites in them, and get infected, completing the cycle.
Find out more about the sneaky life cycle of this worm from this article on Wired magazine, or read the Wikipedia article, or just watch the video that inspired Björk:
The Cape of Good Hope on the Southern tip of Africa is one of the world's great floristic zones: mega-centers of plant biodiversity where the weird and wonderful have made their home. One of these residents, a member of the Iris family called Rat's Tail, Babiana ringens, has an unusual structure that sticks out vertically, looking much like a rodent's nether appendage.
Botanists from the University of Stellenbosch in South Africa have lately suggested that this structure has evolved as a built-in perch for birds that pollinate the plant's flowers (BBC News, Univ. Stellenbosch). They observed that sunbirds were the only pollinators of these plants, and that the birds perched on the stalk while reaching down towards the flowers. Even more compellingly, in regions where the birds had access to other plant species for nectar, the perches were smaller, an instance of "relaxed selection", where a trait is less pronounced when natural selection is acting less strongly.
All this only serves to confirm my prejudice that animals are merely vehicles for plants to move around in.
I live on the 18th floor and have a great view of the Eastern half of Singapore. It's also a great opportunity for bird-watching. What I can see from my window are not pigeons and crows, but those fascinating birds the swifts. Here's a video of one twirling in circles at the same height as my building.
The main problems with swift-watching are apparent from the video: they fly very fast and they're up very high. Living on the top floor solves the second problem but not the first, though sometimes I can get a fleeting close-up glimpse when they return to perch or nest in the roof above me.
When trying to look up more information about them, I found an entry on Ria Tan's website on Sungei Buloh flora and fauna. Swifts belong to a family of birds called the Apodidae, and the common swifts are in the genus Apus, which means "no feet". Swifts actually do have feet, but they're small and used mostly for perching rather than walking.
Here's some interesting facts I learned:
They live most of their life "on the wing" - eating, drinking, mating, and even sleeping
Their name is apt: they're among the fastest fliers in the world, achieving up to 110 km/h
Flying insects make up most of their diet
Swifts are common, although the edible-nest swifts are threatened by indiscriminate nest-harvesting
They're well-adapted to live in anthropogenic environments
Swifts can be confused with swallows, because both have the crescent-shaped wing profile characteristic of fast fliers. The two groups of birds are actually not very closely related. Swifts generally forage at higher altitudes than swallows, fly with a rapid flicking motion, and have shorter tails that are not notched at the ends.
Lately the LTA has been doing some works close to my home for the upcoming Downtown Line of the MRT. Part of Bedok Town Park close to the road has been flattened: the trees cut down and the ground dug into. Quite a number of swifts (among other birds) were circling over that area, fairly close to the ground, and I think they might have been hunting down the insects and other critters churned up by the works.
Japanese scientists have found that small land snails of the species Tomatellides boeningi can survive being eaten by birds. They fed live snails to Japanese white-eyes and a brown-eared bulbul, and found that about 15% of the snails remained alive after passing through the birds' guts.
Just as birds are important dispersers of plant seeds, it appears that they can contribute to the dispersal of small animals too.
Wild populations of T. boeningi on Hahajima Island in the W Pacific show genetic heterogeneity within populations and no evidence of isolation, and there is a statistically-significant positive correlation between genetic variation and the density of Japanese white-eyes, lending support to the idea of bird-borne dispersal.
It helps to have cheeks. We humans drink by forming a seal around the liquid (and often also the edge of a cup or bottle) with our lips, and then sucking inwards (with the help of our cheeks) to draw it into our mouths. This simple process is not available to other animals, such as dogs and cats, which don't really have cheeks to speak of.
I blogged some months ago about how cats lap up liquids. They don't use suction like we do, but as anyone who's watched a thirsty cat knows, it's all in the tongue. They touch their tongues to the surface of the water, and the liquid naturally adheres to the underside of the tongue. By pulling the tongue back quickly, the adhesion of tongue to water and cohesion between water molecules draws up a thin column of liquid into the mouth of the cat. This happens so quickly that it seems like they are 'flicking' water into their mouths - but no spooning or scooping is involved at all.
They're neat and classy, unlike dogs, right? Dogs seem to make a mess whenever they drink, and in the Times article that I linked to in my previous post, the scientists are quoted as saying that dogs scoop water up with the backs of their tongues, instead of elegantly lapping with the tips of their tongues. But this isn't really the case.
Cuckoos have a bad reputation, and it's probably going to get worse. They're known for being brood parasites, depositing their eggs in the nests of other bird species. When these hatch, the cuckoo chicks aggressively demand food from the host parents and also eject their unfortunate step-siblings from the nest. As a result, the cuckoo gets a free pass on child-raising.
It is little surprise that cuckoos coming in to lay their parasitic eggs are often 'mobbed' by the birds that they target, in order to drive them away. However, a recent study has found that 'naive' birds are reluctant to approach cuckoos that have a barred (striped) pattern on their undersides, compared to cuckoos that lack such a pattern. This is interpreted as a form of Batesian mimicry by the cuckoos, taking on the stripes of sparrowhawks, which are birds of prey.
Cuckoos therefore may use two different kinds of mimicry in their lives: as adults mimicking birds of prey to prevent host birds from attacking them, and in the nest mimicking host chicks to convince the host parents to feed them.
Welbergen, J. A. & N. B. Davies, 2011. A parasite in wolf's clothing: hawk mimicry reduces mobbing of cuckoos by hosts. Behavioral Ecology. First published online 21 Mar 2011, doi: 10.1093/beheco/arr008 [abstract].
It's been a while since I've written anything new, and the explanation is straightforward: classes just started up again and have hit me like a freight train. Two weeks in, I've just had a chance to catch my breath.
But I've still been keeping an eye out for interesting articles and news on the Web, and here's my selection of cool stuff from the past week (okay, two weeks...):
Green Porno film star and director talks about her work. Isabella Rossellini's short film series, Green Porno and its follow-up Seduce Me ("A potential sponsor called to say they liked the films but that they couldn't support anything that had the word "porno" in it") are short (1-2 mins), award-winning gems about the peculiar sex lives of different animals. She stars in all of them as the animals, dressing up in fantastic paper costumes (see above).
Vladimir Nabokov's biogeographic theory on the origin of the Polyommatus blues butterflies has been confirmed by lepidopterists using molecular techniques. Aside from being a successful author in both his native Russian and his adopted English (in which he wrote his most famous book, Lolita), he was a great butterfly enthusiast and was for a time curator of Lepidoptera in Harvard's Museum of Comparative Zoology.
Woodpecker skulls inspire the design of more effective shock absorbers. Fun fact: woodpecker skulls decelerate by up to 1200 g each time it hammers (more than 20 times a second!), whereas humans would be concussed by an acceleration/deceleration between 80-100 g.
World Wildlife Foundation launches a new document format, similar to Adobe's PDF format, but which doesn't allow the document to be printed, to raise awareness about excessive paper use. As expected, the file extension is .wwf. Good idea, or gimmick?
The Galapagos Islands, biodiversity hotspot and inspiration for Darwin's theory of evolution, have been taken off UNESCO's list of endangered World Heritage Sites. Doesn't mean that they're out of danger, though. Ironically, the effects of tourism are the greatest threats to the islands today, as the booming tourist industry encourages development and immigration to the archipelago.
"Bird watching" sounds like such a back-to-nature pursuit: just me and my binoculars, hiding behind a bush and waiting for the birds to come out. But with digital cameras making high-quality photography cheap and accessible, and the Internet making sharing those pictures and swapping tips so much easier, birding has become a hobby for the technologically savvy too.
Today, there are crowd-sourced bird-mapping tools, birding packages that double as vacation getaways, birding blogs, birding iPhone apps, and remote-birding Web sites that don't require watchers to be present in the landscape at all. A few old-fashioned birders may still practice their hobby in isolation with binoculars and field guides, but the birding community, these days, has moved on to gather, check, and share sightings across great distances using the fruits of technological industry and the jumbo jet.
This is from an amusing article about the different kinds of birders and the kinds of communities that they form. What the writer calls "privileged aloneness"–getting up to go birding before other people are even awake–seems like a good way to describe the attitude that many birders have.
The way I see it, it's as much about the birds as it is about immersing yourself in the community and its special culture. Just like hardcore runners (or cyclists, or computer geeks) have their own magazines, fashions, gear fads, the same with birders.
Catching up on leisure reading over New Year, I re-encountered the name of Tom Harrisson, who has been described as a "polymath" - pioneering British anthropologist, WWII hero, long-time director of the Sarawak Museum, conservationist, but also a prickly personality whose character invited controversy and divided opinions.
I was pleased to find that a series of documentaries that he co-produced in the 1950s, titled 'The Borneo Story', is available online. One of them, "Birds Nest Soup", which won a prize at the Cannes Film Festival, is embedded above.
These documentaries are a valuable glimpse into the state of Borneo in the postwar period, when it was still a tropical idyll, relatively untouched by large-scale plantation agriculture. Now, of course, birds nest soup is often commercially produced by inducing swifts to nest in abandoned buildings or purpose-built 'hangars', instead of being collected from the wild.
A 2006 BBC documentary, "The Barefoot Anthropologist" (YouTube), hosted by David Attenborough, gives a sense of the man and his exploits, including how he "restarted headhunting in Borneo". It's not all happy memories, though: one of the Australian soldiers under his command during the war describes how he wanted to shoot Harrisson, and is visibly agitated talking about him, half a century on!
The Guardian newspaper's website runs a regular feature called Week in Wildlife, featuring wildlife photos from around the world. It's one of the more popular features they have, and one usually expects to see creatures rare and exotic, but in this week's collection there is a snap of an ashy tailorbird from Sungie Buloh, taken by the KL-based photographer Rahman Roslan. Hidden treasures in our backyard, indeed!
Recent research has shown that bar-tailed godwits (I love common names given to birds) fly up to 11 000 km non-stop in their autumn migration. How's it done? What's long-distance migration good for? A review on long-distance bird migration looks at these questions....
More than just a scrub with soap is needed to save birds affected by oil spill. The deadly Deepwater Horizon oil rig disaster on 22 April is spreading a huge oil slick over the Gulf of Mexico, which may soon reach land.
Oil slick at bottom right (Picture source: BBC)
Cleaning oiled birds is a complicated process, and this Popular Mechanics article describes how. One important step is when they are dried after washing; rescuers have to make sure that their feathers are all aligned, the way that birds normally do when they preen themselves, so that they can remain water proof.
Parasites frequently modify the behavior of their hosts to encourage the infection of new hosts. For example, see this video (taken from the Planet Earth documentary) of the fungus Cordyceps that makes insects climb to the top of grass stems, and then erupts its fruiting body from the host's body, and disperses its spores over more hapless hosts from this elevated position. Yanoviak et al. (Am Nat 2008. Vol. 171, pp. 536–544; DOI: 10.1086/528968) describe a case of parasite-induced mimicry in the ant Cephalotes atratus. A nematode infection causes the gasters (rear portion of the abdomen) to become bright red and swollen, resembling a berry fruit, where normally it is black and inconspicuous. The infected gasters are also full of parasite eggs. Birds that feed on berries would then pop off these packets of parasite propagules, and pass out the eggs in their faeces. Ants congregate around bird faeces, which represent food resources to them, and collect them to feed to their brood, completing the cycle.
Here's the lesson from all this, kids: don't eat dung.
Speech and language seem to be uniquely human traits, which begs the question of how they arose. It turns out that a key regulatory gene controlling human speech, the FOXP2 (forkhead box transcription factor) gene, is also found in other animals, including songbirds. Knocking out these genes in humans (though accidental mutations) results in speech disorders associated with abnormalities in the basal ganglia, though exactly how they control the ability to speak is unknown. A team of German scientists used songbirds as a model for understanding the development of human speech. Instead of simply knocking out the gene, they used RNA interference to reduce FOXP2 levels in a specific area of the basal ganglia, known as Area X, in zebra finches, while they were in the stage of learning their song. This resulted in abnormal song patterns and provides a very persuasive example of how some genes can be directly linked to certain elements of behavior. However, note that the FOXP2 gene is a transcription factor gene that is part of the developmental toolkit, and so functions by regulating the expression of several other genes, so the actual pathway may be much more complicated that it first appears to be, so it would be misleading to simply call FOXP2 the 'speech gene'.
