This kind of surprising discovery helps us understand evolution. Researchers have observed females of the amphibian species Siphonops annulatus nursing their young with a nutritious liquid similar to mammal milk… This challenges our understanding of nursing in the animal kingdom.
Did you know that some spiders can nurse their young? Yes, contrary to long-held beliefs, nursing is not exclusive to mammals. And scientists seem to have more discoveries up their sleeves, with the latest one being published on March 7, 2024 in the journal Science. It’s a rather surprising observation involving females of the species Siphonops annulatus, a serpentiform amphibian belonging to the diverse group of caecilians. Picture yourself in Brazil, observing a creature resembling a snake, nursing its young with a milk-like substance. I know, this image needs some explanation.
Discovery of Maternity in Caecilians
If you’ve never heard of caecilians or gymnophiones, it’s probably because they are the least known group of vertebrates, spending most of their time underground. Since 1987, a team of researchers from the Butantan Institute in São Paulo, Brazil, has been studying this discreet group. With 16 adult females of the species Siphonops annulatus and their offspring – each with 4 to 13 young – the scientists decided to study the lives of these animals during the 2 months following hatching.
It was then that they made a double discovery: not only did the mothers never leave their young, but they also provided them with a milky substance, rich in lipids and carbohydrates, similar to mammal maternal milk! The liquid is secreted by the cloaca, an organ found in birds, reptiles, and amphibians, and excreted through hypertrophied glands along theThe milk of the amphibian, known as Cecilia’s breast milk, is secreted by the mother’s oviduct. This process is triggered by physical or acoustic stimulation, which is a unique form of communication among amphibians. Researchers believe that besides aiding in the growth of newborns, breastfeeding also helps strengthen their immune system through the microbiome, similar to humans. This breastfeeding behavior in Cecilia could be an indicator of an evolutionary stage.
Scientists are unsure about the origins, timing, and reasons for the development of amphibian milk during evolution. There are around a hundred species of caecilians, not all of which lay eggs. Could the combination of egg-laying and milk secretion be an evolutionary step in transitioning from one birthing method to another? Further exploration in the Brazilian forests is needed to uncover clues about the evolution of reproduction strategies.