Caecilians, a mysterious type of limbless amphibian that dwells underground, just got even weirder. Young caecilians effectively eat their mother alive, munching on her tissues to aid with their early development. The mother produces a special layer of fatty skin tissue, which their babies gnaw off using specialized teeth and consume. Mmm, delicious.
It was previously assumed that baby caecilians did this to obtain nutrition, but new research has shown how it also helps mothers to pass on their unique microbiome to their offspring, possibly inoculating their immune systems with feelgood bacteria.
The researchers who made this discovery believe it’s the first time this kind of behavior has been reported in amphibians.
Beyond their peculiar parenting, caecilians are very odd creatures. They are limbless like a worm and feature very small, poorly developed eyes. This is because they primarily live underground and rely on other senses, like touch and chemical detection, to navigate their subterranean world.
The microbiome plays an unbelievably important role in an animal’s health and the function of their immune system – that includes you! While the makeup of an individual's microbiome is impacted by diet and environment, it's also hugely influenced by the mother's own microbiome.
Animals have developed all kinds of strategies for feeding their young and transmitting their microbiomes. Humans and other mammals give their babies breast milk, while birds regurgitate semi-digested food into their chicks' mouths. An especially weird tactic comes from koalas, who feed their young with a special form of poop.
Conversely, amphibians don’t tend to engage in this kind of parental behavior. Frogs, newts, and the like typically lay their eggs in a pond and move on, leaving the young to develop on their own.
Caecilians, however, do have a special relationship with their kids.
“When you find the eggs, you always find the mother. I've never seen a juvenile without an attending mother,” Marcel Talla Kouete, first author of the study and a doctoral candidate in the University of Florida School of Natural Resources and Environment, said in a statement.
In the new research, published earlier this year, scientists at the Florida Museum of Natural History and the University of Massachusetts studied Herpele squalostoma, a caecilian species found in the soil of central Africa that participates in skin-feeding behavior.
They took bacteria samples from the skin and guts of 14 juveniles, nine female adults, and six male adults from Cameroon, as well as their surrounding environment, and looked to see how the microbes were distributed among the group.
This showed that every juvenile shared a significant part of their skin and gut microbiome with their attending mother. They believe the young pick up this bacteria via close skin-to-skin cuddles, as well as this unique skin-feasting.
Strange as caecilians may seem, this behavior means their parenting is arguably more similar to humans than most other amphibians; it's just like a mother feeding her baby with breast milk, albeit slightly more grisly.
The study is published in the journal Animal Microbiome.