#modelorganisms

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Observing animal behavior is essential to understanding their biology and improving their well-being, both in the wild and in captivity. This also applies to model organisms, species used in scientific research. These animals are often studied in laboratories to investigate complex biological phenomena in controlled environments. However, natural habitats are more complex, and animal behavior may differ significantly between the lab and the wild.

For example, in laboratories, the small freshwater fish medaka (Oryzias latipes) is known to court and spawn shortly before dawn. But does this happen the same way in nature? A research team from Osaka Metropolitan University set out to find out. Despite the widespread use of this species in scientific studies, little is known about its natural ecology. To bridge this gap, researchers installed underwater cameras in a watercourse in Gifu, Japan, monitoring a wild population for ten days. The video analyses confirmed the nocturnal activity of the species, revealing surprising findings.

First, medaka fish began spawning around midnight, several hours earlier than reported in laboratory studies. From that moment on, swimming activity increased rapidly, peaking between 1 and 3 AM. Male medaka displayed two main courtship behaviors: chasing females and performing rapid circling in front of them, particularly intense between 2 and 3 AM.

But why does medaka reproduce at night? Researchers hypothesize that this behavior helps reduce the risk of predation on eggs and adults. Many fish species reproduce at night or twilight when predators are less active. Additionally, medaka does not rely solely on vision for courtship but uses chemical signals to recognize mating partners, allowing them to reproduce even in the dark.

These discoveries add new insights into the natural behavior of medaka and could improve its care in captivity by creating less stressful laboratory environments. Understanding model organisms in their natural habitat not only enhances animal welfare but also improves the reliability of scientific research.

See You Soon and Good Science!

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