The duck who grows a scaffold in its webbing
one. A chick embryo and a duck embryo start with the same feet: toes, with webbing stretched between them. The chick dismantles its webbing cell by cell, until only separate toes remain. The duck keeps it. That asymmetry was the whole story for decades: one bird demolishes, the other cancels.
two. A new study says the duck does more than cancel. About a week into the egg, researchers found small clusters of cartilage cells living in the duck's webbing. The cells leave patches of collagen, and the webbing's tiny arteries line up toward them. The webbing keeps working vessels through the exact window when the chick's collapse.
three. The duck's webbing still runs self-dismantling chemistry of its own. What differs is the plumbing: blood keeps tissue alive, and while vessels stay, the membrane grows. The authors suspect the little cartilage crews keep them. They call the patches transient. Scaffolding, not skeleton.
four. Scaffolding is normal on a building site. The duck's version shows up mid-egg, holds the channels open while the foot is still only a plan, and is not part of the toes that stay. Botelho and colleagues, Royal Society Open Science, 2026. PMID 42729023.
Sources: Botelho et al., Royal Society Open Science (2026). doi:10.1098/rsos.260583 · PubMed 42729023
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