Lund University has found that their dung balls aren’t just take-away meals—they’re also portable coolers.
In North America’s Sonoran desert, there’s a fly that depends on a cactus. Thanks to a handful of changes in a gene called Neverland, Drosophila pachea can no longer make chemicals that it needs to grow and reproduce. These genetic changes represent the evolution of subservience – they inextricably bound the fly to the senita cactus, the only species with the substances the fly needs.
The Neverland gene makes a protein of the same name, which converts cholesterol into 7-dehydrocholesterol. This chemical reaction is the first of many that leads to ecdysone – a hormone that all insects need to transform from a larva into an adult. Most species make their own ecdysone but D.pachea is ill-equipped. Because of its Neverland mutations, the manufacturing process fails at the very first step. Without intervention, the fly would be permanently stuck in larval mode. Hence the name, Neverland—fly genes are named after what happens to the insect when the gene is broken.
Fortunately, in the wild, D.pachea can compensate for its genetic problem by feeding on the senita cactus. The cactus produces lathosterol—a chemical related to cholesterol. D.pachea’s version of Neverland can still process this substitute, and uses it to kickstart the production of ecdysone.
The senita is the only plant in the Sonoran desert that makes lathosterol, the only one that lets the fly bypass the deficiency that would keep it forever young. It has become the fly’s dealer, pushing out chemicals that it cannot live without, and all because of changes to a single fly gene.
In 2010, an article in Rolling Stone likened the investment bank Goldman Sachs to “a great vampire squid wrapped around the face of humanity, relentlessly jamming its blood funnel into anything that smells like money.”The creature it was referring to does exist – it’s not a true squid, but one of their close relatives. But despite its terrifying name and appearance, it’s not a vampire. It doesn’t suck blood. It doesn’t have a “blood funnel”.
In fact, thanks to newly published observations, we now know that the vampire squid is a garbage-eater. It extends living fishing lines from its body to snag a rain of rubbish falling from the surface, getting fat on a menu of faeces and corpses.
The Goldman Sachs metaphor still works, doesn’t it?
The vampire squid belongs to the cephalopods, the group that includes squid, octopuses and cuttlefish. But it’s an evolutionary relict that appeared well before any of these more familiar animals. Its body is gelatinous and blood-coloured, as if the internal organ of a larger animal had broken free. It swims with two wing-like flaps, sees with opal-blue eyes, and lights up the surrounding water with flashing organs found all over its body, and especially at the tips of its arms.
Two of these arms have been modified into white thin filaments, which coil up into special pockets, and can extend to 8 times the animal’s length. The other eight arms are connected by a cloak-like web that can be inverted over the vampire squid’s body to reveal a muddy charcoal interior, lined with fleshy spines. You can see where the name comes from.
The vampire squid lives all over the world, but we know very little about what it does. That’s partly because it lives at incredible depths – 600 to 900 metres below the surface, in pitch blackness. This level is known as the oxygen minimum zone (OMZ) and unlike the vampire squid, it’s well-named. While a few animals thrive here, most are choked off by the lack of oxygen.
The vampire squid copes by having an incredibly slow metabolism, blood proteins that hug oxygen molecules with an unyielding grip, and a body that so closely matches the density of water that it neither floats nor sinks. It rarely wastes energy on unnecessary movements. It simply hangs in the darkness.
But even though it lives life in the slow lane, the vampire squid needs food, and that’s in short supply in the oxygen minimum zone. What does it eat? To find out, H