Baby spiders are born with big eyes, just like puppies are born with big feet

August 3, 2019, 9:09 a.m.
baby jumping spider
Photo: Wanchat M/Shutterstock

Baby jumping spiders are about the size of a bread crumb. But despite their tininess, they fit some amazing capacity in those microscopic eyes.

Researchers at the University of Cincinnati found that baby spiders can hunt prey just as their parents do because their vision is nearly as good.

"Spiderlings can adopt prey-specific hunting strategies. They can solve problems. They're clever about navigating their environment," said Nathan Morehouse, study co-author and assistant professor of biological sciences, in a news release. "This suggests their eyes are providing as much high-quality information when they're small as when they're large."

In the study, published in the journal Vision Research, Morehouse and his team found that baby spiders have roughly the same number of photoreceptors — the cells in the retina of the eye that convert light into signals sent to the brain — as adults. The photoreceptors are smaller, however, and are shaped differently so they can pack into a smaller space.

Researchers used a custom-made micro-ophthalmoscope, similar to those used by eye doctors, to carefully look into the tiny eyes of spiderlings.

They found that the baby spiders start off with eyes that are much larger in proportion to the rest of their fuzzy bodies.

"And the bigger the eye, the better it functions. The more light it captures and the more in focus objects are," Morehouse said. "So one strategy is to start life as close to your adult eye size as you can."

This growth pattern is called negative ontogenetic allometry. A spider's huge eyes are similar to a puppy's monstrous feet.

"People say, 'That's going to be a big dog' because of the size of the puppy's feet," Morehouse said. "A puppy grows into its feet in the same way that jumping spiders grow into their eyes."