Saturday, 11 August 2012

Inter-tidal event at West Beach Local Nature Reserve

This is the first of 4 educational sessions I am leading on West Beach Local Nature Reserve Littlehampton, West Sussex.
The nature reserve is a SSSI, a site of special scientific interest.

A major feature are the sand dunes (rare in Sussex) which run along the back of the beach and stretch off to the west.
Sand dunes form when sand blown from a large area of exposed sand travels up the beach and forms mounds. These can starts as sand builds up around a piece of drift wood, a rock or a clump of dried seaweed.

Grasses, such as marram grass, grow on the dunes and the roots help stabilize the sand.
Even so, sand dunes are very susceptible to damage from trampling and so parts of the dunes are fenced off to protect them.
Many small flowering plants grow on the sand dunes and in turn provide a valuable habitat for birds, sand lizards, bees, butterflies and other invertebrates. 

Between the sand dunes and the sand exposed at low tide is a large area of flint cobbles, which eroded from chalk cliffs way back in the past history of the coastlines formation.
Growing amongst the flint pebbles are special vegetated shingle plants such as sea kale and yellow horned poppy. Vegetated shingle is also a rare habitat.

At low tide a wide expanse of sand is uncovered by the tide creating a fascinating habitat.
Worms and other invertebrates live beneath the sand.

Today’s tidal event focused around the pier area where tide pools provide temporary homes for marine life and permanent attachment for animals such as mussels, limpets, barnacles and sea anemones.

Attached to the wooden supports were a large number of algae grazing limpets. 

As we explored along the pier we discovered a large number of dog whelks. Looks can be deceiving, not an algae grazer, these are predators. we found the usalwhite coloured dog whelks and also some of the orange variety.
Dog whelks can drill a hole through the shells of a mussel using its radula – sharp teeth on a conveyor belt like tongue. However its takes about 2 days for the dog whelk to bore through the shell. The dog whelk produces a secretion that softens the shells making boring much easier.

Once the hole has been bored into the shell the dog whelk injects a secretion that paralyses the mussel.  Digestive enzymes are secreted into the shell and the dog whelk sucks up the mussel-soup.

In one of the larger pools beadlet anemones remained open as they were covered by water. Sea anemones look like plants but they are infact animals related to jellyfish.
Their tentacles swaying waiting fir a small fish or prawn to blunder into the tentacles upon which the anemones will sting and paralyze its prey before passing it to the mouth in the centre of the tentacles. Sea anemones do not have eyes, so rely on touch. They are able to tell the difference between food and their own tentacles so they don’t attempt to eat part of themselves.

While we did not find any shore crabs, a girl who was rock pooling nearby caught this hermit crab.
Unlike other crabs, they don’t have a hard shell protecting the main part of their body, so they live in empty seashells – like this whelk shell.

As we waded out into the water, shoals of small fish swam around our legs.
A special find was this juvenile Solenette (Slipper Sole). This species often lives around the mouths of rivers.
Like other flatfish they can change colour to match their surroundings, helping them to avoid predators and to catch food.

Now you see me…

Now you don’t…

They often burry themselves just beneath the surface of the sand where the can catch passing prey.

A great day of tide pooling. The next event on Tuesday will have a lower tide and we will be able to explore further along the pier.

1 comment:

city said...

thanks for sharing.