Waterwereld

the dog whelk

The Dog whelk is a common gastropods, that can be found on rocky shores around the North sea and west Coast of the USA. Here it feeds on mussels and acorn barnacles. They can be found in rockpools, in harbours, in estuarine waters but they prefer the rocky shores. The dog whelk has a thick and sharply pointed spiral shell. Dog whelks are unedible for humans, because of its nasty taste.


Dog whelk on the left, Pelican's foot and European painted top shell or Calliostoma zizyphinum and the northern cowrie or Trivia Arctica.
from the book :"year at the shore", from: P.H. Gosse, 1864.

the dog whelk and the mussel

The mussel is protected by its shell. The dog whelk uses it radula a tongue covered with sharp teeth. It bores a hole in one of the valves and injects an acid into the mussel. But the dog whelk is a slow eater, it takes more then a week to eat a mussel. Other mussels start defending themselves and try to adhere some glue to the dog whelk. This glue is called byssus and this adhesive glues the dog whelk to the rock. As it remains immobilised the dog whelk will dy of starvation.

the dog whelk and the offspring

The dog whelks starts to form groups in spring. The eggs are laid in groups of 5 under rocks or in crevices. Dog whelks gather for mating in spring. Eggs are laid in yellow capsules in rocky crevices during April and May; Soon the first young whelks appear, and consume the other eggs. The whole process of growing up takes three years:

the dog whelk predators

Birds and crabs are the most important enemies. Especially the Eiders and oystercatchers consume large amounts of the dog whelks.

the dog whelk and imposex

There is very little of the poison tributyl needed to start the development of male sex organs on the female dog whelk. This is called imposex. The dogwhelk almost disappeared from the North sea by the cause of this disease.


fouling on hulls

The accumulation of barnacles and goose barnacles on boats is called fouling and reduces the speed of a boat. It will also increase fuel consumption. Mechanical removing the barnacles is a costly operation and removing it without damaging the hull can be next to impossible. Its much easier to use anti-fouling bottom paint, commonly known as bottom paint.: This is a toxic paint used to prevent the attachment of these organisms. Certain forms of this paint, although effective, can be harmful to other marine life if not applied and removed properly. If a boat is longer then 25 meter the toxic TBT was added to the anti-fouling paint.

tributyltin of TBT

For 40 years TBT was used as a biocide in bottom paint. The use of TBT has come to a stop in the western world, but is still the most effective and cost efficient, and it is being used in countries with poor regulation enforcement, like the Caribean Islands. The danger of TBT used on the ship hulls was found to leach into, and severely damage, the marine envirronment. TBT has has a strong toxic and long lasting impact to invertebrate development: snails, worms, barnacles and bivalves and all the higher animals that depend on them as a food. Skipjack tuna sea-otters and dolphins accumilate the TBC in there bodies. The common whelk has almost dissapeared because of the use of TBC.

imposex

The common whelk has almost dissapeared because of the use of TBC. These animals were affect by TBC causing imposex. Imposex is a disorder in sea snails caused by the toxic effects of TBT. TBT cause female sea snails like the common whelk to develop male sex organs Reproduction of the seasnails comes to a stop.



Whelks, Periwinkles and limpets on an illustration of P. Kuckuck.
1 European Sting Winkle or Murex erinaceus or Ocenebra erinacea
2 Common Whelk or Buccinum undatum with eggs
3 Purple Sea Snail or Dog Whelk or Purpura lapillus with eggs
4 netted dog whelk or Nassa reticulata
5 pelican's foot or Aporrhais pespelecani
6 the large necklace shell or Euspira catena or Natica catena with house
7 Common Turret-Shell or Turritella communis
8 Common Wentletrap or Scalaria communis or Epitonium clathrum
9 Common or Edible periwinkle or Littorina littorea
10 Flat Periwinkle or Littorina obtusata
11 rough periwinkle or Littorina saxatilis
12northern lacuna or Lacuna vincta
13 Grey Top Shell or Gibbula cineraria
14European Painted Top Shell or Calliostoma zizyphinum
15Blue-rayed Limpet or Patella pellucida
16 Common Limpet or Patella vulgata
17 Grey Chiton or Lepidochitona cinerea



P. Kuckuck

Dr Paul Kuckuck is the writer of the book "Der Strandwanderer". The first edition started in 1905, the last one in 1977.
On this website you can find these illustrations :
barnacles
the sea slater
 starfish
 light-bulb tunicate
 Whelks, limpets and periwinkles
 Sponges and sea anemones
 Cockles
 sea beech
 Oarweed
 teredo worm or shipworm
 hydrozoids

 sea-lettuce or ulva