Paper wasps with earthworm-like characteristics produce a special milk for their young

These worm-like creatures secrete nutritious milk from their butts to nourish their hatchlings. This is the first known example of an amphibian feeding its young in this way.

American paper wasp (Siphonops anulatus) is a legless, egg-laying amphibian found on dark, moist forest floors throughout South America. It can reach up to 45 centimeters in length, with a deep blue cylindrical body surrounded by white grooves.

American paper wasps are born with spoon-shaped teeth. They use these to feed on their mother's skin, which is rich in lipids and proteins.

“But this skin nourishment only happens once a week,” he says carlos jared At the Butantan Institute in São Paulo, Brazil. That's not enough food to maintain the young's growth rate, he says, with some cubs growing 150 percent larger within the first week of life.

To find out where their extra nutrition is coming from, Jared and his colleagues filmed 16 female ringed wasps and their hatchlings.

The researchers observed the newly hatched chicks wriggling around the edges of their mother's body several times a day, often nibbling or sticking their heads into the rear opening known as the vent.

Closer examination of the footage showed that droplets of a milk-like substance were frequently spilled into the vent openings, suggesting that the chicks were actively feeding on it.

Analysis of the milk revealed that it contained fat and carbohydrates. “These carbohydrates are very important,” say team members Pedro Maillo-Fontanathe Butantan Research Institute also provides hatchlings with the energy they need to grow.

The researchers also discovered that touch and sound signals from hatchlings stimulate milk production in the mother's oviducts, or glands within the fallopian tubes.

Some paper wasps that give birth to live offspring secrete nutritious fluids for the fetus inside the mother's body, while amphibians produce fluids to nourish their offspring outside the body, Mailho-Fontana said. This is the first time that this has been found to be the case.

“The paper wasp is a real surprise box,” says Jared. “They are very secretive and live in an underground world that is different from the one above. They adapt to a world that is completely different from the one we know and invent some new behaviors to survive. There was a need.”