rockpools and tidepools

Rockpools or tidepools are filled with seawater during high tide and exist as separate pools at low tide. The can be food in the intertidel zone between rocks. These small lakes have a constantly changing environment — fluctuations in water temperature, salinity, and oxygen content. This is caused by exposure to midday sun ,low temperatures in the winter, rain (that changes the salinity of the water) and evaporation. Gulls visit the tidepools during low tide looking for an easy meal. During high tide there are strong waves and currents. There is much difference in the tide pools that are refreshed daily and the tidepools that are higher up the beach. Only the hardy animals and plants can survive.

There are many birds that feed on the inhabitants of the rockpools: seagull, Kentish plover, oystercatcher On top of the preditors inside the rock pool is the shorecrab and heremit crab. Other preditors can here be seen: the plumose anemone or frilled anemone and Sea urchins.


Barnacles are well adapted to water loss due to desiccatin when the tide is low. In fact the different barnacle species that live in the upper tidial zone live at very tightly constrained elevations. Tidal conditions precisely determine the exact height of an assemblage relative to sea level. Their calcite shells are impermeable and strong, they have two plates that they slide across their mouth opening when not feeding. Birds are not able to open these plates. Barnacles are distributed in zones : Two common species of acorn barnacle, Chthamalus montagui and C. stellatus can be found on the European shores. Chthamalus stellatus settling in greater proportions low on the shore and in exposed areas and C. montagui settlement predominating higher on the shore and in sheltered areas.

Limpets, barnacles and mussels can be seen on this rock wall. The starfish is there enemie

Limpets are herbivorous animals feeding on algae they scrape off the rock they live on.


Waves can dislodge mussels and draw them out to sea. Mussels close there valves when the tide goes out, the midday sun can heated them up or dry them out, during winter they can get frozen.

The shore crab

The shore crab lives in the tide pool and collect everything they like to eat , which is almost everything. Small and flat and very active, these crabs scuttle about when not hiding under rocks and in crevices. They hide often as evey moving shadow will frigten them. The danger comes from aboves: gulls eat them.


The plumose anemone or frilled anemone (metridium senile) can be found under stones, beneath overhangs and in shaded places. The feed on the zooplankton that is brought with the currents: copepods, worm larvae, mollusc larvae, ascidian larvae, amphipods and barnacle larvae are eaten.

a tidepool, an illustration of Theo Carreras, 1903. "The world of animal live".
1 strawberry anemone
2 beadlet anemone
3 beadlet anemone
4 cockles
5 common starfish
6 Scallop
7 purple shell
8 periwinkle
9 acorn-barnacles
10 dulse
11 mussel
12 Blackheaded gull

Rockpool of west Atlantic coast of the USA, made by Hashime Murayama.
1 dogwhelk or Nucella lapillus,
2 black mussel
3 rock barnacle or Balanus balanoides
4 tortoiseshell limpet of Tectura testudinalis.
5 mossanimal or bryozoa sp
6 hydroid or Hydrozoa sp
7 sea anemone or
8 furbelowed whelk or Latirus amplustre
9 common periwinkle or winkle or Littorina littorea
10 sea peach or Halocynthia aurantium
1 tubed gable weed or Polysiphonia lanosa
2 knotted rockweed or Ascophyllum nodosum
3 pink carolline or encrusting Corallines algae,

Hashime Murayama

Hashime Murayama was a Japanse illustrator,
born in 1879. He used to work for
National Geographic until 1941: Here he
produced many beautiful illustrations.
On this website you can see:
man of war
sturgeon, caviar