But as interesting as the concept of legless caecilians wielding their penises underground might be (admittedly, it disturbed some of my older Italian relatives until I explained the spelling differences), information about caecilian cannibalism began emerging from Marvalee Wake’s lab at the University of California, Berkeley. The herpetologist extraordinaire was looking at fetal and newborn individuals from several viviparous species and began investigating the function of their peculiar-looking baby teeth (better known to scientist-types as deciduous dentition).
While some of the teeth were spoon-shaped, others were pronged or resembled grappling hooks, but none of them resembled adult teeth. Wake also performed a microscopic comparison of caecilian oviducts. She observed that in pregnant individuals, the inner (i.e., epithelial) lining of the oviduct was thicker and had a proliferation of glands, which she referred to as “secretory beds.” These glands released a substance that fellow researcher H.W. Parker had previously labeled “uterine milk.” Parker described the goo, which he believed the fetuses were ingesting, as “a thick white creamy material, consisting mainly of an emulsion of fat droplets, together with disorganized cellular material.” He also thought that the caecilians’ fetal teeth were only used after birth, as a way to scrape algae from rocks and leaves. Wake, however, had her doubts, especially since she noticed that these teeth were resorbed before birth or shortly after.
Pressing on with her study, Wake saw something odd. In sections of oviduct adjacent to early-term fetuses, the epithelial lining was intact and crowded with glands. However, in females carrying late-term fetuses, the lining of the oviduct was completely missing in the areas adjacent to the fetuses, although it was intact in regions well away from the action. Wake proposed that fetal caecilians used their teeth before birth to scrape fat-rich secretions and cellular material from the lining of their mother’s oviduct. Although this behavior couldn’t be seen directly, she had gathered circumstantial evidence in the form of differences in the oviduct between early-term and late-term individuals. After an analysis of fetal stomach contents revealed cellular material, Wake had enough evidence to conclude that caecilian parental care extended beyond the production of uterine milk and into the realm of cannibalism. Unborn caecilians were eating the lining of their mothers’ reproductive tracts.
But if the consumption of maternal epithelial cells in viviparous caecilians gave this admittedly strange behavior a cannibalistic slant, it was in the egg-laying species that the story really took off.
In 2006, caecilian experts Alexander Kupfer, Mark Wilkinson, and their coworkers were studying the oviparous African caecilian, Boulengerula taitanus, when they made a remarkable discovery. This species had been previously reported to guard its young after hatching, and the researchers wanted to examine this behavior in greater detail. They collected 21 females and their hatchlings and set them up in small plastic boxes designed to resemble the nests they had observed in the field. Their initial observations included the fact that the mothers’ skin was much paler than it was in non-moms and that hatchlings had a full set of deciduous teeth resembling those employed by their oviduct-munching cousins.
Intrigued, the researchers set out to film the parental care that had been briefly described by previous workers. On multiple occasions, Kupfer and Wilkinson observed a female sitting motionless while the newly hatched brood (consisting of between two and nine young) slithered energetically over her body. Looking closer, they noticed that the babies were pressing their heads against the female, then pulling away with her skin clamped tightly between their jaws. As the researchers watched, the baby caecilians peeled the outer layer of their mother’s skin like a grape . . . and then they consumed it.
Scientists now know that these bouts of “dermatophagy” reoccur on a regular basis and that the mothers’ epidermis serves as the young caecilians’ sole source of nutrition for up to several weeks. For their part, female caecilians are able to endure multiple peelings because their skin grows back at a rapid rate.
“The outer layer is what they eat,” Wilkinson said. “When that’s peeled off, the layer below matures into the next meal.”