Biological complexity: new structure found in bird retina (Introduction)

by David Turell , Tuesday, December 17, 2019, 18:50 (1803 days ago) @ David Turell

Flycatchers need to see fast moving prey:

https://phys.org/news/2019-12-newly-retinal-vision-birds.html

"The foundation of avian vision rests on cells called cone and rod photoreceptors. Most birds have four cone photoreceptors for color vision, a fifth cone for non-color-related tasks, and a rod for night vision. Each cone photoreceptor cell contains a spherical structure called an "oil droplet," which filters light before it is converted to electrical signals by the visual pigments, enhancing color discrimination.

"However, the researchers have discovered a never-before-seen type of cone structure in the retina of a group of small songbirds, called flycatchers. Instead of an oil droplet, it contains a high- energy-producing cellular structure called "megamitochondria" surrounded by hundreds of small, orange-colored droplets. The researchers named this novel cellular structure a megamitochondria-small oil droplet complex, or MMOD-complex.

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"Traditional cones were present throughout the retina of these flycatchers, and their density decreased moving away from the center toward the periphery. However, the MMOD-complex photoreceptors were present only in the central region of the retina, an arrangement that could help birds detect flying insects, said Esteban Fernandez-Juricic, a professor of biological sciences at Purdue.

"'The retina of flycatchers, which are sit-and-wait predatory birds, evolved a novel cellular structure in a photoreceptor that may allow them to detect, track and capture fast-moving prey, like insects," he said."

Comment: Another complex structure requiring design by a designer.