Here’s a great idea for a super-power: what if by merely emitting a sound, you could detect nearby friends and enemies in the way the sound echoes? Echoes. Echoes.

For many species of bats and dolphins, echolocation isn’t a super-power but a necessity. It allows these animals to hear predators and prey without seeing them in the dark skies or cloudy oceans. This adaptation evolved separately in these mammals—a great example of convergent evolution.

Scientists at Queen Mary, University of London were curious how this type of convergent evolution looked at the genomic level. So they compared the complete genomes of 22 mammals, including new sequences of four bat species, to look at how echolocation is expressed in the genes.

To perform the analysis, the team had to sift through millions of “letters” of genetic code using a computer program developed to calculate the probability of convergent changes occurring by chance, so they could reliably identify “odd-man-out” genes.

Remarkably, they found genetic signatures consistent with convergence in nearly 200 different genomic regions! “We had expected to find identical changes in maybe a dozen or so genes but to see nearly 200 is incredible,” explains Queen Mary team member Joe Parker. “We know natural selection is a potent driver of gene sequence evolution, but identifying so many examples where it produces nearly identical results in the genetic sequences of totally unrelated animals is astonishing.”

Although many of the gene region similarities are in genes involved in hearing, which the team expected, others are all over the place, reports ScienceNOW:

…some genes with shared changes are important for vision, but most have functions that are unknown.

The team published their findings last week in Nature.

“These results could be the tip of the iceberg,” says group leader Stephen Rossiter. “As the genomes of more species are sequenced and studied, we may well see other striking cases of convergent adaptations being driven by identical genetic changes.”

So perhaps not a super-power, but a regular occurrence…

Image: Greg Hume

A leggy neighbor

The leggiest animal on the planet lives just south of San Francisco, according to a new report in ZooKeys. Illacme plenipes comes the closest to the description of a millipede than any of its relatives—females have as many as 750 legs!

Even millipede researcher Paul Marek thinks Illacme plenipes is special. Its plentiful legs have claws and National Geographic News lists more of its cool features:

…massive antennae (relative to the scale of its body), which the millipede uses to feel its way through the dark; a jagged and translucent exoskeleton; and body hairs that produce a sort of silk that may help Illacme plenipes adhere to the undersides of boulders. And unlike in other millipedes, the mouth of this species is specifically structured for piercing and sucking plant tissues.

Wanna get to know your neighbor? Movies and images are available for download here.

Insect hearing aids

A recent publication in Science explores how certain rainforest katydids are able to listen like mammals do, but much more efficiently. Katydids’ hearing organs are near the insects’ knees, and much like human ears, gather sounds from the air and transmit them to the brain in fluids.

For humans and other mammals, sounds are collected by the eardrums in vibrations, which are transferred by three ear bones to the cochlea. Fluid in the cochlea translates these sounds and sends them to the brain.

In katydids, the ear bones are missing, simplifying the process. (An excellent comparison illustration is available at Scientific American.) This simplification could lead to better hearing aids for humans, according to the lead author of the study, Fernando Montealegre-Z. “These findings change our views on insect hearing and open the way for designing ultrasensitive bio-inspired sensors.”

Insect-inspired water bottles

Finally, recent news reports describe a new company creating water-collecting bottles for “the most arid regions of the world.” Their inspiration? The Namib Desert beetle. Wired UK describes the insects’ process of water collection:

The beetle survives by collecting condensation from the ocean breeze on the hardened shell of its wings… The beetle extends and aims the wings at incoming sea breezes to catch humid air; tiny droplets 15 to 20 microns in diameter eventually accumulate on its back and run straight down towards its mouth.

Want more exciting entomology?

How about disease-fighting ladybirds? Learn more at ScienceShot. Insect movie stars? Watch their cameos at the New York Times.

Katydid image: Fernando Montealegre-Z and Daniel Robert

According to the textbook, An Introduction to Marine Ecology, “A typical coral colony forms several thousand larvae per year to overcome the odds against formation of a new colony.” The larvae have to act quickly to find a safe place to land and establish a colony or they will die.

Recently, Dutch scientists discovered that, like baby reef fish, coral larvae use sound as a cue to find those safe places.

According to their abstract in PLoS One:

Free-swimming larvae of tropical corals go through a critical life-phase when they return from the open ocean to select a suitable settlement substrate…. Here, we show that coral larvae respond to acoustic cues that may facilitate detection of habitat from large distances and from upcurrent of preferred settlement locations.

The team designed a “choice chamber” (a device that  offers small test subjects two or more contrasting conditions and allows them to move freely towards the one they prefer), put coral larvae into it and played them recordings of a coral reef. The results clearly showed that the flea-sized larvae were strongly attracted to the noise.  This presumably influenced what they then perceived as a suitable habitat within the chamber.

How these creatures detect sound is unknown, but Dr. Steve Simpson, one of the authors of the study, offers, “At close range sound stirs up water molecules, and this could waggle tiny hair cells on the surface of the larvae, providing vital directional information for baby corals.”

Understanding how these vulnerable animals complete their lifecycle is essential to ensure appropriate management. Coral reefs around the world are already under threat from various conditions like global warming and ocean acidification. Now you can add noise pollution to the list.

Dr. Simpson states that, “Anthropogenic noise has increased dramatically in recent years, with small boats, shipping, drilling, pile driving and seismic testing now sometimes drowning out the natural sounds of fish and snapping shrimps.”

With this study (and according to it), “The alleviation of noise pollution in the marine environment may gain further urgency.” Here’s hoping we listen up…