Learned behaviour

It is usually only the large whelks that follow after Leptasterias polaris while it is eating, smaller whelks are probably more vunerable. The violent movements of the shell which is part of its defence are always seen amongst adults, but very seldom amongst the young. This can be because defensive behaviour developes as the whelk gets older or because those individuals that defend themselves survive to became adults. The high rate of mortality amongst the young (shell length = 3-5cm) would support this hypothesis. When the starfish is not eating or in motion, whelks flee from this predator, whelks that have lived together with starfish have learned when it is best to keep their distance and when to approach. Snails that have not lived close to Leptasterias polaris do not show this defensive behaviour.

Genes steer

During evolution, whelks that have drawn closer to eating starfish have recieved relatively more food than those that have avoided starfish and probably have greater luck when reproducing. The whelk that is "brave and smart" has also spread its genes to a greater extent than those that are "cowardly and stupid". They have adapted and developed a defence against those predators that exist in their surroundings. This development occurs quite rapidly as the whelk does not roam over large areas and mix its genetic structure with individuals from areas with other types of predators. The ability to adjust its behaviour according to the presence of predators and food suggest that the whelks nervous system can coordinate information to a greater extent than what is normally believed to exist amongst other invertebrates.


Previous page

Page 6 of 15

Next page

Way of life

What they eat




Fishing for whelks

Common whelk    More facts     Other names
Home    Contents    Inspiration    Facts    Collaboration   
© Aquascope 2000   Tjärnö Marine Biological Laboratory, Strömstad, Sweden
Bo Johannesson | Martin Larsvik | Lars-Ove Loo | Helena Samuelsson