Exploring Pembrokeshire's Rockpools

Rockpools are exciting places to explore especially with children. But sometimes when your child asks you what they have found in their bucket you are unable to say.

Here is some more information about a few of the most common species, to start you off on your rockpooling adventure.

Beadlet anemone

These are usually red but can be green or brown .
They look like blobs of jelly when the tide is out but extend their tentacles out when the tide comes back in.
These are animals and not plants and have stinging cells in their tentacles which they fire out into their prey to paralyse it .
The tentacles can then move the food to their mouth in the centre.
These animals can eat small prawns and fish.

Snakelocks anemone

These beautiful anemones cannot retract their tentacles and so are usually found in rockpools where they remain covered in water even when the tide goes out.
Like the beadlet anemone they use their stinging cells to catch their prey.
The green colour of the tentacles is due to algae living in the tissues of the anemone.
Some snakelocks anemones are light brown because they don't contain algae
Although the sting of the anemones is not sufficient to harm humans, some people with sensitive skin may get a rash, so it's best not to touch the tentacles of any anemones.

Strawberry anemone

These look like larger versions of the beadlet anemone, but they have lots of green/yellow spots on the main body (so they look like strawberries)
They like to keep out of light and heat and so are often found under overhangs and in crevices

Barnacles, crabs and prawns (crustaceans)

Barnacles

Although it doesn't look like it, these animals are related to prawns and crabs When they are larvae, they settle on a rock and cement their head to it They then build a shell around themselves and close themselves in When the tide comes in they open a 'trapdoor' at the top of their shell and stick their feathery legs out into the water to catch particles of food which float past

Edible crab

These are an orange / brown colour and look like a pasty with their crimped edge
They are difficult to spot as they often wedge themselves into a crevice They will grow quite quickly and can reach 30cm across! They have very large pincers which they use to crush and eat mussels and marine snails

Hermit crab

This crab is the only one not to have its own shell. They live in the empty shells of dog whelks, topshells or periwinkles. As they grow larger they need to find new shells to live in and will even rip another hermit crab out of a shell if they want it enough.



Shore crabs

These are very common and are usually green but can be brown or orange. They can be recognised by the jagged edge to the front of their shell. They grow to about 10cm across the carapace (shell). Like most crustaceans they have to moult their shell every so often as they grow bigger This usually happens about 4 times in the first year alone.


Spider crab

These crabs have very long legs which make them less agile than other crabs and more vulnerable to predators To help disguise themselves they cover their shell with bits of debris, sand and seaweed This camouflage also enables them to hunt more effectively They have quite a lot of sharp spikes on their carapace to further ward of predator

Marine snails, limpets and mussels (molluscs)

Dog whelk

This is a carnivorous animal that has a 'drill' like tongue which they use to drill a hole in the shell of a mussel, limpet or barnacle. When they have drilled a hole through the shell, they use acidic liquid to dissolve the body of the animal inside. They can then 'suck' up their meal This process takes a long time (hours or days depending on what is being eaten) and so they may get washed off in the tide before they are able to get their meal.

Limpets

These common creatures can live up to 20 years and are very important for the ecology of the seashore They slide around when the tide is in scraping seaweed off the rocks with their rough tongue When the tide goes out, limpets return to exactly the same spot and this is called their home scar They can grind down the rock with their shell to get a nice tight fit so that they are able to retain moisture until the tide comes back in.

Mussels

These animals like areas of rapid water movement and there you will find them in abundanceThey are filter feeders and when the tide comes in, they will open slightly to allow water and food to pass through Mussels attach themselves to the rock using strong threads, called byssus threads.

Periwinkles

Periwinkles are grazing herbivores, most of them eating microscopic seaweed (invisible to the naked eye)They are found at all levels of the shore At the top of the shore (furthest from the sea), the rough periwinkle can be found (pictured) whereas further down the shore, the edible periwinkle dominates.

Starfish and Brittle Stars

Brittle stars

As the name suggests, these animals are extremely fragile and should not be handled.Brittle stars are related to starfish but they have very long thin arms attached to a more obvious central disc.They may be found under stones and seaweeds on the lower shore.

Cushion starfish

These can be very difficult to spot as they are very small, only a few centimetres across.They can vary in colour but are usually an orange / green colour. These animals are scavengers and feed on detritus (particles of decaying animal and plant matter) They all begin life as males, maturing at 2 years old, and then at the age of 4 they become female! They usually live for up to 7 years.They may be found hiding in seaweed or underneath stones on the lower shore (near the sea at low tide) Underneath their legs are lots of tiny sucker feet, which can be damaged if handled.