Supralittoral Zone

Spray Zone : Also called the Upper Littoral, the Supralittoral Fringe, the Littorina Zone (because it is often dominated by Littorina species) the Splash Zone,upper Balanoid and the upper Barnacle Belt. This area is dry much of the time, but is sprayed with salt water during high tides. It is only flooded during storms and extremely high tides. Organisms in this sparse habitat include barnacles, isopods, lichens, lice, limpets, periwinkles, and whelks. Very little vegetation grows in this area.

Splash Zone or Supralittoral?

Some literature makes the distinction between the spash zone and the supralittoral zone but its is often unclear what the distinction is so I am treating this area above the normal high tide mark as one zone.

Conditions are extremely variable over time, making this a harsh place for organisms to survive. Frequently affected by salt spray and strong winds, most plants and animals can be found in the relative shelter of numerous nooks and crannies amongst the rocks and on cliff faces.

The barnacle zone is the first clearly demarcated zone at the top of the shore and this zone occurs on almost every shore in the world. Below this zone and marking the beginning of the lower intertidal zone is the clearly marked zone of brown algae.

Within the supralittoral zone, lichen grow on the rocks, as well as any plants that are capable of contending with occasional seas spray. Below this, in the supralittoral fringe, cyanobacteria blue-green algae, grow in a slippery film creating what some biologists call the "black zone", due to the dark color of the algae-covered rocks. Animals that tolerate more air than water live here.

The small pieces of shell and sand particles that make up the beach are always on the move, and are constantly washed by water and blown by wind. There is little protection for anything living there, so animals burrow into the sand or live between the grains of sand. Here they are protected from waves, sand movements and predators.

No large plants grow on sandy shores but pieces of dead plants are washed in by the waves. Microscopic algae, called diatoms, are found in the water and between the sand particles. The many small animals living between the sand grains form an entire foodweb, including grazers, predators, scavengers and detritivores (animals eating tiny fragments of decaying food).

Many animals use tidal, lunar or seasonal rhythms to help them survive. Thus plough snails burrow into the sand at mid-tide to avoid stranding on the high shore. Small, white sandhoppers and ghost crabs are both nocturnal scavengers. During the day the sandhoppers bury themselves in the damp sand of the high-tide mark and the ghost crabs retreat to deep burrows. By being active at night they avoid both predators and the hot, drying sun.

Animals of the sandy shore are dependent on seawater to keep them moist, and to supply them with oxygen and food in the form of small pieces of dead plants and animals.

Talitrus saltator : Sandhopper

Talitrus saltator is a supralittoral amphipod usually found beneath or amongst debris and decaying algae deposited at the high water mark or during the day it may be buried at depths between 10-30 cm in the substratum.

Description: Talitrus saltator is an active supralittoral sand-hopper, growing up to 20 mm in length. It has a typical gammaridean body-plan, dorso-laterally compressed with three main divisions, head, pereon (thorax) and pleon (abdomen), both pereon and pleon are segmented and smooth. Antennae are distinct and one is much longer and robust than the other. Eyes are round and black, the body being grey-brown in colour.

We did some work with T. saltator in the lab on visual orientation to the sun. They orientate themselves by light and dark boundaries which is pretty cool really.

Hydrobia Ulvae : Laver Spire Shell

Typically found on muddy sand, in estuaries and salt marshes. Sometimes also in lagoons and other areas of reduced salinity. Frequently associated with seagrass beds. Highest densities found mid-tidally but has been recorded down to 100 m depth.

Description: A small spiralling shell with six whorls. Up to 6 mm high but more typically around 4 mm. The shell is brown to yellow in colour. The body of the snail is a clear grey frequently with various pigment spots.

Mud feeder, feeding on Mud sediments with its radula, scaping diatoms, bacteria etc from the sediment and substrata.

We have done various experiments in the lab with H. ulvae including measuring speed of movement in water of different temperatures.

Phylum: Mollusca
Class: Gastropoda
Order: Mesogastropoda
Family: Hydrobiidae

Barnacles :

Although barnacles may look like mollusks with their shell-like covering, they are actually crustaceans, related to lobsters, crabs and shrimp. The barnacle secretes the calcium-hard plates which totally encase them. In larvae stage they swim and look like tiny shrimp. Upon maturing they swim the waters until they find the right place to stop. They then attached them self to this selected area head first.

The barnacle uses a brown glue like substance to attach itself firmly. The barnacle attached itself so strongly to a surface that the its cone base is still around long after the animal has died. Dentists have studied this glue like substance to learn more about its adhesive values.

More barnacles are features on the Littoral zone pages

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