Talk about a multi-purpose tool. Several species of tropical moth can rasp their genitals against their abdomens to beam loud ultrasound signals at approaching bats, possibly throwing the hunters off course1.
Bats and moths have been engaged in a natural arms race for nearly 65 million years, each evolving strategies to outwit the other. Scientists have long known that members of the tiger moth family blast bats with ultrasound signals resembling the echolocation calls bats make as they search for, or close in on, prey. But tiger moths were assumed to be the only moth group able to imitate the bats’ signals.
Behavioural ecologist Jesse Barber of Boise State University in Idaho and phylogeneticist Akito Kawahara of the University of Florida in Gainesville went to Borneo to try their luck with hawkmoths, a large family of excellent flyers, many of which are found in the tropics. After luring them with lights, the researchers grabbed the spiny-legged insects by hand — “We suffered quite a few punctured fingers getting good at it,” Barber says — and trussed them up in harnesses made from fishing line and drinking straws.
'A really good strategy'
When the researchers played bat ultrasound to the hawkmoths, they found that three species (Cechenena lineosa, Theretra boisduvalii and Theretra nessus) they had captured emitted ultrasound clicks in response. The males did so by rapidly grating stiff scales on the outer surface of their 'claspers' — structures normally used to grab females during mating — against part of the abdomen, the researchers report. Females also seem to pull part of their genitalia inwards so that genital scales rub against their abdomens.
The purpose of this behaviour is not known. Perhaps the moths’ ultrasound serves as a boastful warning to bats of the hawkmoths’ barbed legs and excellent aerial skills. Or maybe the hawkmoths are jamming the bats’ sonar, as one species of tiger moth has been shown to do2. Either way, the fact that hawkmoths can also make ultrasound clicks means it is likely that “there are even more insect groups that make sounds back at bats”, Barber says. Clearly it is “a really good strategy for insects to deploy”.
The new finding is “really, really cool”, says neuroethologist John Ratcliffe at the University of Southern Denmark in Odense. The hawkmoths and the tiger moths both have ears that can detect bat sonar and structures to make bat-like ultrasound clicks, although each has those organs in very different places. The hawkmoths have ears on their faces, whereas tiger moths' ears are on their thoraxes. And the tiger moth makes ultrasound clicks with membranes on its thorax. That makes the two species a prime example of evolutionary convergence, the appearance of similar features in separate groups of animals.
“At both ends, in ears and sound production, it’s double convergence, which is really neat,” says Ratcliffe.
This story originally appeared in Nature News.
Also on HuffPost:
The Atlas beetle (pictured) can push around 850 times its weight.
Largest Invertebrate (Land)
The coconut crab weighs about 6.6 pounds and its legs can span up to two and a half feet Liz Hall from the Melbourne Aquarium inspects Coconut Crab as he takes possesion of a coconut in Melbourne, 19 December 2006. They Coconut crab (also known as the Robber Crab) are the largest living crab in the world and can climb coconut trees to harvest coconuts which they can break with their huge nippers and have been gruesomely know to feed on injured or unconcious people in the bush. (William West, AFP / Getty Images)
The giant squid is the world's largest invertebrate, and the largest ever measured was 59 feet long. Giant squids also have the largest eyes of any animal, each one about the size of a human head.
The etruscan shrew is the smallest mammal (by weight) in the world. The smallest animal by skull size is the bumblebee bat.
Most Venomous Animal
The sea wasp jellyfish (pictured) has enough venom to kill 60 adult humans. Photo: <a href="http://www.flickr.com/people/65578066@N00" target="_hplink">Guido Gautsch/Flickr</a>
Arctic terns migrate about 11,000 miles to the Antarctic each year...and then come all the way back! An Arctic Tern dives down to protect its nest on June 24, 2011 on Inner Farne, England. (Dan Kitwood, Getty Images)
Blue whales' low-frequency pulses can be heard over 500 miles way. At 188 decibels, these sounds are louder than a jet engine. In this picture taken on March 26, 2009, shows a blue whale swimming in the deep waters off the southern Sri Lankan town of Mirissa. (Ishara S. Kodikara, AFP / Getty Images)
World's Most Extreme Animals
North African ostriches run up to 45 miles an hour, making them the fastest land bird. They are also the biggest, weighing up to 345 pounds. An african ostrich eats at the Addo National Elephant Park, north of Port Elizabeth, on June 24, 2010. South Africa is hosting the 2010 FIFA World Cup. (Patrick Hertzog, AFP / Getty Images)
Peregrine falcons dive toward their prey at over 200 mph. A young male Peregrine Falcon eats meat taken from the protective glove of Taronga Zoo bird trainer Erin Stone (unseen) following a short flying lesson in Sydney on December 9, 2009. (Greg Wood, AFP / Getty Images)
Sailfish can swim at speeds of up to 68 mph, although experts disagree as to just which species of sailfish is the fastest. Sailfish jumping out of the water on January 16, 2006 in the Florida Keys, Florida. (Ronald C. Modra, Sports Imagery / Getty Images)
Cheetahs can run at speeds up to 70 mph. Majani, a 2-year-old male African cheetah, exhibits lighting speed Friday, March 19, 2004 while chasing a mechanical rabbit at the San Diego Zoo's Wild Animal Park as part of the Park's environmental enrichment program. (Ken Bohn, San Diego Zoo / AP)
Three giant tortoises are estimated to have lived over 175 years, with one estimated at a whopping 255 years. Image: Harriet, who died in 2006, was thought to be the third longest-lived tortoise on record. <a href="http://www.flickr.com/photos/doctorow/123660557/" target="_hplink">Cory Doctorow/Creative Commons</a>
World's Most Extreme Animals
African elephants are the heaviest and second tallest land animals. Large males can exceed 13,000 pounds and are 12 feet tall at the shoulder. This photo made on February 10, 2011 shows an elephant in Tsavo west national park, some 350 kilometres southeast of Nairobi. (Tony Karumba, AFP / Getty Images)