Photo of researchers carrying out fieldwork along a rocky coastline

Changing Sealife - Snail Survey

Capture photos of our eco-sensitive design experiments along the coast and become an Ecostructure citizen scientist.

Are there changes to sealife along your coast?
Get involved and take our Seashore Snail Survey

Warm-water species heading north

As the Earth’s climate changes, warming seas and milder winters are allowing species previously found only in southern and western parts of Ireland and Britain to survive further north and east. On rocky seashores, various species of seaweeds, snails, limpets, barnacles and sea anemones are being found in places where they have never been recorded before. Monitoring these changes is important, as it helps us to understand the impact that climate change has upon our coastal wildlife and ecosystems.

Have you seen a dogwhelk, purple topshell or toothed topshell on the coast of Ireland or Wales? If you have then WE WANT TO KNOW ABOUT IT!


Coastal defences such as sea walls and rock armour protect coastal towns, roads and railways from flooding and storms. These structures are usually made of rock or concrete, so they can provide homes for rocky shore wildlife in places where the natural shore is sandy or muddy. It is possible that by building these defences, we have unintentionally helped southern species move northwards by providing stepping stones across areas of sand or mud. The need for coastal defences is likely to increase as climate change brings higher sea levels and more frequent storms. It is important to understand the effects that these structures have on our wildlife and ecosystems.

The Seashore Snail Survey

We are collecting information on the effects of climate change and coastal defences on three species of rocky shore snails. All of them are easy to find and identify. These are:

The toothed topshell Phorcus lineatus
A southern species which is migrating north in Britain and Ireland. Easily recognised by its circular aperture (trap door), distinctive tooth, zigzag markings and pearly underside

The purple topshell Steromphala umbilicalis
Also has a circular aperture but is easily recognised by its purple stripes and the distinctive hole (umbilicus) in its underside.

The dog whelk Nucella lapillus
A predatory snail that is particularly fond of barnacles. It has an unmistakeable pointed shape and its shell opening has a distinctive canal and toothed ridge. The shells of dog whelks are hugely variable in colour. While the majority of dog whelks are white, some are brown, orange, yellow or purple and some have banded colour patterns. See how many different colours and patterns you can find! You can also look for dog whelk egg cases. These look like clusters of yellow rice grains and are usually found in damp crevices.

All three species are found on rocks in the intertidal zone; the part of the shore that is covered by the sea at high tide but exposed at low tide.

Download here: Seashore Snail Guide

What information are we looking for?

We need citizen scientists in Ireland and Wales to explore their local rocky shores and coastal defences, recording dog whelks, toothed topshells and purple topshells wherever they find them. If you use a mobile phone, the Ecostructure Observatory web site will record the location of your records and will allow you to upload photographs so that our experts can confirm your species identification.

How to get involved with the Snail Survey

  1. Identify a rocky area of seashore in the intertidal zone (below the water level at high tide). This can be natural or artificial. We are particularly interested in artificial rock or concrete structures surrounded by sand or mud.
  2. Search for snails on the surfaces of rocks, in gullies and at the edges of rock pools. Always consider your own safety and seek permission before venturing onto private property.
  3. Record the number of toothed topshells, purple topshells, dog whelks and clusters of dog whelk eggs that you find and upload to the Ecostructure Observatory.
  4. Upload photographs (one of each species) to confirm identification.
  5. Record the amount of time spent searching and the number of people conducting the search.
  6. Record the type of habitat in which each species was found.
Illustration of crabs, mussels and starfish on the beach


Sightings of toothed topshell, purple topshell and dog whelks

Illustration of a paper map and magnifying glass

Tell us where you found it!

Are the species on natural rocky shore, stone wall, rock armour, concrete structure or a wooden structure?

Start inputting your information to the map now!