A reticulated glass frog (Hyalinobatrachium valerioi) vigilantly rests atop its developing embryos on the underside of a small leaf. Glass frogs are named after their transparent bellies, so clear that you can see their internal organs, blood vessels, and beating heart (though the heart is mostly obscured by other tissues in this species). It’s astonishing to see up close the homologous organs we find in our own bodies, all residing in a miniature vertebrate body just a couple of centimeters in length.
Initially it was thought that glass frogs exhibited little parental care, with some evidence of paternal care. However, paternal care has since been described in many species, and in 2017 a study by Delia et al. found that glass frogs showed remarkable diversity in parental care and egg-tending strategies. Through examining around 40 species in the Centrolenidae, they found previously unknown patterns of maternal care in which the female broods the eggs for a short period of time after oviposition. In the reticulated glass frog, the male soon takes over and guards the eggs through night and day. During this period he tends to the eggs, making sure they remain hydrated through absorbing water from his skin and even emptying his bladder onto the clutch (called hydric brooding). The male frog will also continue calling to other females to father more offspring. Individual males have been observed guarding more than a handful of clutches simultaneously. If approached by other frogs, he will defend the area where his clutch resides, resorting to wrestling if the antagonist doesn’t back down. Eggs are vulnerable to predation from wasps and other arthropods, and glass frogs will use their elastic hind legs to fling away potential threats. This species also sports a golden spotted dorsal patterning, which has been suggested to be an egg-mimicking color scheme, taking an invader’s attention away from the nutritious developing embryos.
Photographed after slight disturbance [2], as the frog moved around its egg mass due to my presence (unless otherwise stated)
