The male is enticed by smell

When it is time to mate, the males move towards the females. Temperature appears to be the triggering factor and causes the females to release feromones that attract the males. Along the Atlantic coast of North America where the water is relatively cold, mating usually occurs during the late spring and summer when the water is warmer. Individuals in the egg capsules develope more quickly in warm water, which is an advantage in areas with many predators. Along the coasts of Europe, because of the Gulf Stream, water temperatures are higher. Here, mating takes place during from late autum to early spring, which is probably because high temperatures are disadvantageous for the development of embryos and there are less predators. The whelk eats less during the mating season, but even high summer temperatures place them under stress and they are less active.

Large production of eggs

The eggs are kept in capsules and a female can normally lay up to 140 egg capsules, each containing about 2000 eggs.

Two females laying their egg capsules together.

The division of the sexes is quite equal amongst the whelks. The females mate often and with several different males and the snails that hatch from the eggs have a greater genetical variation.


The female, in contrast to the male, cannot mate every year because it takes longer than a year for the female to produce eggs.
   After mating, the sperms can be stored within the female for up to eight weeks and consequently can decide the time and place for egg laying. The eggs are layed on hard substrate in shallow water.
   The larger the female, the larger the number of eggs that are layed and therefore more young snails that develope in each capsule. With the lack of hard substrate, females lay their eggs together and it is not uncommon with egg collections numbering up to 3000 egg capsules. These collections are sensitive to wave activity and after stormy periods it is not uncommon to see eggs washed up onto the beach.
   Whelks surround their egg collections with capsules that are either empty or contain very few eggs. These capsules can represent about 10% of the total number of capsules and is probably a defence mechanism against predators such as sea-urchins. Sometimes, empty egg capsules are found washed up onto the beach.



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