Rock Pooling
When you next go to the beach why not have a look in the rock pools which are exposed
at low tide? These pools are home to lots of plants and animals which need to stay
underwater when the tide goes out, so they take shelter here. Print this guide out and
take it along to help you.
When you next go to the beach have a look in the rock pools which are exposed at low
tide. These pools are home to a lot of plants and animals which need to stay underwater
when the tide goes out, so they shelter in the pools. The pools may look tranquil
compared to the sea but life here is very harsh; the water can get very warm in the sun
and can even dry up if it gets too hot and when it rains the water becomes less salty
and more like a pond than the sea. So all the plants and animals you see have had to
adapt in special ways to live there.
Here are some pictures of the
plants and animals you are likely to
see in this area but you will
probably see many more once you
start looking….
This picture shows sea anemones
(pronounced an-em-on-ees) in a rock
pool at Hackley Bay. They are
animals which attach to the rocks in
sheltered parts such as rock pools
and under big rocks to protect them
from the waves. Anemones feed by
drawing food in through their mouths which is in the centre amongst the tentacles-they
only have one opening though as they are very basic animals so they go to the toilet out
of the same hole as what they use to eat! Beware, the tentacles you see on a anemone
are stinging-do not touch! Anemones come in many different colours but usually you will
see red ones. They only have their
stinging tentacles out when they are
covered with water so at low tide
they will look like the picture below.
This is what anemones look like at
low tide -little blobs of jelly. They
close up like this so they don't dry
up when they are not under water.
The picture below shows a 'home scar'
of a limpet. The scars are where the
limpets go back to each night after they
have finished feeding. The limpets make
these scars by using acid from their
bodies to dissolve a little hole in the rock
which is exactly the right size for their
shell, this makes it easier for them to
hold on in big waves and stop the water
coming into their shell.
This is a typical rock pool, there are lots
of empty shells in the bottom but some of
these will be used by other animals as a
new home, such as the hermit crab. There
is also some red seaweed but look
carefully as it comes in all shapes, sizes
and colours-you will see seaweeds in red,
brown and green.
Zonation
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At the top of the beach is the splash zone – splashed occasionally by the waves
but never submerged. Very little lives here – it is a sort of limbo zone where
terrestrial plants can’t survive because they can’t tolerate the salt spray, but
marine life can’t survive because it’s too dry. Lichens live here.
On the upper shore it is more dry than it is wet but it does get submerged
during the peak of the high tide. Things that can survive long periods out of the
water survive here, such as periwinkles and dog whelks.
The middle shore is wet for longer period but is still completely exposed to the
air at times. Here you will find barnacles, limpets and wracks.
The lower shore is below the mean low water mark so is only occasionally
exposed during low spring tides. Here you will find the kelps.
Effects of light
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Seawater absorbs different wavelengths (or colours) at different rates. Red is
the first to be absorbed.
You will find green seaweeds on the upper shore for the same reason you find
green plants on land – they do not use the green wavelengths for photosynthesis
so they reflect it and appear green.
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You will find brown seaweeds in the middle and lower shore as less red light is
available.
In rock pools and below the low water mark where the seaweeds are
permanently covered in water you will find the reds. There is no red light for
them to use so they reflect it.
Don’t get too bogged down in this – it can get complicated if you think about
it too much!
Holding on
Plants and animals on the shore are pounded
by waves and pulled by currents so have
employed various methods of holding on.
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Glue/cement-Barnacles permanently
fix themselves to the rocks and never
move once they are settled.
Suck hard! Some animals suck onto
the rocks with a big muscular ‘foot’ –
periwinkles, dogwhelks, the snail type
things.
Tying up- Mussels exude sticky
threads, which they hope will become entangled on seaweed or other life, and
hold them on.
Hide-Many animals would rather just hide than expose themselves to the
hazards of waves – look under rocks and in crevices and you will find the more
vulnerable, less protected animals- anemones, worms, shrimps, etc.
Holdfasts-Terrestrial plants get water from the soil through their roots but
seaweeds live in water so don’t need roots for this purpose. They do, however,
need to hold on so have ‘holdfasts’ for this purpose and these can sometimes
look like roots.
GOING ROCK POOLING
WHERE? -There are many good places to go rock pooling south of Aberdeen –
Catterline, Stonehaven, Muchalls are some. North of Aberdeen the coast changes and
there are miles and miles of sandy beach. There are some sites for rock pooling though
– Rockend on Forvie NNR, Collieston and Peterhead Lido.
WHEN? - Before you go check the tides. Tide times can usually be found in local
newspapers and times for the next 7 days can easily be found on the Internet. There
are about six hours between high tide and low tide, so try to time your visit so that you
are there at low tide to catch sight of the things at the bottom of the beach before
the sea covers them again. The rock pools nearest the sea, lower down the beach will
have the most interesting life in them as they are generally bigger and deeper and are
only cut off from the sea for a short time.
WHAT? to take – You can enjoy rock pools by taking absolutely nothing at all and just
be amazed by looking at things where they live. For a more detailed investigation the
following items may be of use:
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Appropriate footwear – In the winter, wellies obviously keep your feet dry but
can be slippery. In the summer, beach shoes or sandals that can get wet are fine
but watch those exposed toes. The best things if you have them are wetsuit
boots.
A tub or bucket – clean, empty margarine tubs are great for seeing life that you
collect and want a closer look at.
A net – tea strainers are brilliant for catching smaller beasties, or a small
aquarium net. Large nets on long sticks can be a bit unwieldy and a hazard to
others around you.
Wipes or gel – if it is not possible to get to a tap and soap, take something to
wash your hands before you have anything to eat or drink after you go rock
pooling.
A guide book
Just remember the golden rules of rock pooling;
-always go with an adult
-do not touch the plants and animals as many rock pool animals can sting, bite and pinch
-always carefully replace all overturned stones
-do not pull seaweed off the rocks-it can take years to grow back
-if you take any shells home make sure they are empty first, you never know what might
be lurking inside!
-tread carefully to avoid slipping on the wet rocks
-please take your litter home with you or put it in a bin
-keep an eye on the tide and last but not least
-HAVE FUN