March 22, 2010
When the amphibious moths are in larva form, as caterpillars, they "can breathe and feed indefinitely both above and below the water’s surface and can mature completely submerged or dry," the researchers write. They add that since the larvae inhabit fast-flowing streams where floods are common, they have evolved remarkable skills to "withstand extremely high and fast floodwaters, which can scour the rainforest streambeds for days during frequent storm events. Through a combination of specialized shelter-seeking behavior and use of silk tie-downs and drag lines, larvae avoid exposure to the strongest currents."
The caterpillars are also notable for the feeding habitats: they are the first caterpillars known to eat snails and mollusks, which they bind with their silk.
The researchers speculate that since the caterpillars have no gills or plastron, they "likely rely on direct diffusion of oxygen through the hydrophilic skin". This would explain why the caterpillars only occur along fast-flowing steams and why they perish in stagnant water.
As strange as these amphibious evolutionary adaptations appear, the researchers believe that these four moths evolved amphibious traits not once, but several times in a phenomenon known as 'parallel evolution' where different species evolve similar traits separately.
"Similar patterns of parallel evolution in which related taxa independently derive similar ecologies has also been found in Hawaiian birds and damselflies," the researchers say. In addition, a lack of aquatic insects on the Hawaiian Islands may have provided an open niche for the caterpillars to take advantage of.
The moths are in need of active conservation measures according to the researchers, since they are threatened by habitat loss due to streams being diverted for culverts and dikes. At one time there may have been more amphibious caterpillars but the paper concludes that they "may already be extinct" due to habitat destruction.
Per square mile the Hawaiian Islands have more recognized endangered species than any other place in the world, hence its nickname: Endangered Species Capital of the World. Hundreds of species have already vanished from Hawaii since Europeans first arrived in the late 18th Century; several more species are known to have disappeared when the Polynesians first arrived.
CITATION: Daniel Rubinoff and Patrick Schmitz. "Multiple aquatic invasions by an endemic, terrestrial Hawaiian moth radiation." PNAS. www.pnas.org/cgi/doi/10.1073/pnas.0912501107.
Cricket mothers warn offspring about spiders before they hatch
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(02/04/2010) Researchers have long been fascinated by how insects migrate thousands of kilometers, for example from Britain to the Mediterranean. A new study, published in Science shows that although tiny, insects are not at the mercy of winds as expected. Instead they employ sophisticated flight behaviors to use fast winds to their advantage.
Loss in biodiversity may be killing bees
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UK planning to reintroduce insects
(01/17/2010) When one thinks of reintroducing wildlife, one usually thinks of big charismatic mammals, such as wolves or beaver, or desperate birds like the Californian condor. But the Royal Society for the Protection of Birds in Scotland is going one step further to save its unique ecology with plans to reintroduce four species of dwindling insects.
Researchers catch new cricket species going where no cricket has gone before
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