Recent Evolutionary Development

The transition from egg-laying to live birth in some snail species, like the rough periwinkle, is a relatively recent evolutionary change, happening within the last 100,000 years​

Genetic Changes

The shift to live birth in these snails is driven by approximately 50 genetic changes scattered across the snail's genome. These changes have accumulated gradually over time

Unique Birthing Process

Unlike mammals, in some snail species like Littorina saxatilis, it's the babies that may do the hard labor of crawling out of the mother's body into the world

Diverse Shell Types and Habitats

 Littorina saxatilis exhibits a wide variety of shell types and habitats, making it one of the most misidentified creatures, often mistaken for different species

Protective Birth Strategy

Live birth might provide better protection to the newborns from environmental threats like drying out, physical damage, or predators, compared to egg-laying

Adaptation and Spread

This reproductive strategy has allowed the species to adapt and spread into new areas, some of which were not suitable for egg-laying snails

Misidentification Over Centuries

 Littorina saxatilis has been described as a new species or subspecies more than a hundred times due to its shell variations and different habitats

Egg Retention Evolution

 The switch to live-bearing may have begun with increased egg retention time, eventually leading to eggs hatching inside the mother

Physical and Physiological Demands

The transition to live birth placed new demands on the snails’ anatomy, physiology, and immune system, requiring various adaptations​

Continuous Research and Discovery

Researchers continue to study these snails to understand the specific functions of the genetic changes and how they contributed to the development of live-bearing​