Nieuw: Component


In the animal kingdom there are many examples of ways in which an individual can manipulate its mating partner to its own benefit. One bizarre example is the phenomenon of dart shooting in hermaphroditic land snails. In many species, a so-called “love dart” is forcefully stabbed through the skin of the mating partner. In Cornu aspersum (previously Helix aspersa) this results in the injection of an allohormone that increases sperm storage and paternity, probably via a decrease in sperm digestion. This project aims at investigating the darts shape, function and use within as well as between species of different families of land snails. Within species nothing is currently known about, for example, the diversity in dart shapes between individuals from different populations. Between species there is a large diversity in dart shapes and numbers. In addition, these darts are stabbed in very different ways. In none of these species has it been established whether the dart has a similar physiological effect on the recipient as the demonstrated effect in C. aspersum.

Besides looking at love darts, other odd sexual organs, such as elaborate accessory glands and dart-like stabbing devices in snails and slugs, can be addressed. All this information about the function and use of these sexual attributes is essential for a full understanding of the evolution of such odd reproductive acts.

At the MSc level collaborations with colleagues abroad are possible (e.g., Cuba, Greece, Japan, Malaysia). Please contact me for details.


– Behavioural observations
– Electron microscopy
– Geometric morphometrics
– Histology
– Molecular phylogeny reconstruction
– Paternity analysis
– Physiology
– Quantifying behaviour

Essential reading:

Reyes-Tur, B., Allen, J.A., Cuellar-Araujo, N., Hernández, N., Lodi, M., Méndez-Hernández, A.A. & Koene, J.M. 2015. Mating behaviour, dart shape and spermatophore morphology of the Cuban tree snail Polymita picta (Born, 1780). Journal of Molluscan Studies 81: 187–195

Zizzari, Z.V., Smolders, I. & Koene, J.M. 2014. Alternative delivery of male accessory gland products. Frontiers in Zoology 11: 32

Koene, J.M. & Schulenburg, H. 2005. Shooting darts: co-evolution and counter-adaptation in hermaphroditic snails. BMC Evolutionary Biology 5: 25

Koene, J.M. & Chiba S. 2006. The way of the samurai snail. American Naturalist 168: 553-555.


Dr. Joris M. Koene
Room: H-147
Phone: +31 (0)20 – 59 87095

Personal page Joris Koene
the koene group