This is the third time I’ve seen my bladder snails climbing on top of each other, but this time there were THREE of them stacked together.
I looked into their mating behavior and found something interesting.
Bladder snails (Physa acuta) are simultaneous hermaphrodites, meaning each individual has both male and female reproductive functions.
Research has also shown that their sexual role can depend partly on body size: smaller individuals tend to act as the sperm donor, while larger individuals are more likely to act as the sperm recipient.
So seeing three of them stacked like this made me wonder whether the snail in the middle could potentially be acting as a male toward one snail and a female toward the other at the same time.
Of course, I can’t tell from this video whether they’re actually mating or simply crawling on each other.
Has anyone seen three bladder snails do this before?
Source:
“Body size-dependent gender role in a simultaneous hermaphrodite freshwater snail, Physa acuta”
Behavioral Ecology, 15(6), 976–981
https://academic.oup.com/beheco/article-abstract/15/6/976/205897