Nature's wonders: pointy end eggs (Introduction)

by David Turell , Thursday, August 23, 2018, 18:58 (2073 days ago) @ David Turell

They are used by shore birds who live on rock cliff coastlines without nests to keep the eggs from rolling off:

https://cosmosmagazine.com/biology/for-cliff-dwelling-birds-pointy-eggs-are-best

"A study confirms that for cliff-nesting birds, pointy eggs are best.

"Common murres or guillemots (Uria aalge) are small seabirds in the auk family that nest in colonies on steep rocky cliffs. The birds lay their eggs directly on the cliff ledge, without a protective nest.

"The eggs have distinct pointed shape, which protects them from plunging into the ocean if they are laid on a sloping surface, or if a parent bird kicks them. Instead of travelling in a straight line, they roll in a circle, coming to rest where they began.

***

"The trademark pointiness and its very clear adaptive benefit to the survival of the murres and other members of the Uria genus have intrigued researchers since the 1980s. It was clear that the egg shape was keeping the eggs on the cliff, but the exact physics was hard to pin down.

***

"The findings, published in the Journal of Experimental Biology, confirmed previous hypotheses – that conical eggs are more likely to stay put. The key measure, they found, was the relationship between the resting angle of the egg – determined by its shape – and the steepness of the slope on which it lies.

“'In general, an egg's conicality was the most reliable predictor of its likelihood of staying put on inclined surfaces," Hauber says. "This finding provides experimental support for natural selection shaping the unique form of murre eggs amongst all bird eggs.'”

Comment: These eggs cannot have been developed by chance attempts if the birds were to survive. Only design fits.