Tide pool - WikiHQ

thumb|upright=1.2|A tide pool in [[Porto Covo, west coast of Portugal]]

A tide pool or rock pool is a shallow pool of seawater that forms on the rocky intertidal shore. These pools typically range from a few inches to a few feet deep and a few feet across. Many of these pools exist as separate bodies of water only at low tide, as seawater gets trapped when the tide recedes. Tides are caused by the gravitational pull of the sun and moon. A tidal cycle is usually about 25 hours and consists of two high tides and two low tides.

Tidal pools are theorized to be one possible environment where life on Earth originated, with the chemical reactions needed for life's beginnings potentially occurring in these shallow, dynamic environments. Additionally, the conditions within tidal pools, such as the presence of fluctuating water levels and unique chemical concentrations, may have also driven the evolution of land-walking vertebrates from ancient fish approximately 400 million years ago.

Some examples have been artificially augmented to enable safer swimming (for example without waves or without sharks) in seawater at certain states of the tide.

Tidepooling is an educational and recreational activity in which people visit tidepools formed during low tide to view the rock formations and living organisms they contain. Unlike scuba diving or other underwater ways of viewing undersea life, tidepooling is a low-risk activity that does not require expensive equipment or extensive logistics.

The intertidal fringe: area around the high-tide mark.
The intertidal or littoral zone: area between the high and low-tide marks. Can be further divided into high, mid, and low intertidal zones, which are explained below in more depth. Although tide pool organisms must avoid getting washed away into the ocean, drying up in the sun, or being eaten, they depend on the tide pool's constant changes for food.

Fauna

The sea anemone Anthopleura elegantissima reproduces clones of itself through a process of longitudinal fission, in which the animal splits into two parts along its length. The sea anemone Anthopleura sola often engages in territorial fights. The white tentacles (acrorhagi), which contain stinging cells, are for fighting. The sea anemones sting each other repeatedly until one of them moves.

Some species of sea stars can regenerate lost arms. Most species must retain an intact central part of the body to be able to regenerate, but a few can regrow from a single ray. The regeneration of these stars is possible because the vital organs are in the arms.

Sea urchins move around tide pools with tube-like feet. Different species of urchin have different colors, and many are seen in tide pools. With their spines that protect them from predators, they allow the urchins to feed almost undisturbed in tide pools. The spines of some species, such as Toxopneustes pileolus, are toxic, capable of delivering an extremely painful sting when touched. Algae and other microorganisms are the food sources that attract the urchins to the tide pools.

The presence of the California mussel increases the supply of inorganic nitrogen and phosphorus in coastal marine tide pools which allows the ecosystem the nutrients to be more productive. The shell of a California mussel is primarily composed of aragonite and calcite which are both polymorphs of calcium carbonate. Climate change and ocean acidification has led to a decrease in these amounts important compounds in California Mussel shells over many years.

thumb|Hermit crabs in a tide pool

Many species of hermit crab are commonly found in tide pool environments. The long-wristed hermit crab (Pagurus longicarpus) has been found to become stranded in tide pools and are forced to inhabit gastropod shells in response to the rapidly changing temperature of the pools. Hermit crabs of different or the same species compete for the snail shells that are available.

Many fish species can live in tidepools. Tidepool fishes are those inhabiting the intertidal zone during part or the entirety of their life cycle, including residents displaying morphological, physiological and behavioral adaptations to withstand the fluctuating environment and non-residents that use the intertidal as juvenile habitat, feeding or refuge ground, or as transient space between nearshore areas. Tidepool fishes can be classified as residents and non-residents (sometimes called transients or visitors). Residents are those that spend the whole lifetime in the tidepools. Non-resident species are commonly divided into two groups: secondary residents (also known as partial residents or opportunists) and transients (which can be further classified as tidal and seasonal transients). Secondary residents are species that spend only a portion of their life history in tidepools, typically during their juvenile stage, before moving on to adult subtidal habitats. This is a behavior known as homing. These fish crawl on the floor of tide pools using a back and forth movement of their tail fin and a rotating motion of their pectoral fins.

Multiple species of Amphipods (Amphipoda) can be found in coastal tide pools. These small crustaceans provide an important food source for predator species as well as limiting the growth of algae attached to vegetation.

Flora

Sea palms (Postelsia) look similar to miniature palm trees. They live in the middle to upper intertidal zones in areas with greater wave action. High wave action may increase nutrient availability and moves the blades of the thallus, allowing more sunlight to reach the organism so that it can photosynthesize. In addition, the constant wave action removes competitors, such as the mussel species Mytilus californianus.

Recent studies have shown that Postelsia grows in greater numbers when such competition exists; a control group with no competition produced fewer offspring than an experimental group with mussels; from this it is thought that the mussels provide protection for the developing gametophytes. Alternatively, the mussels may prevent the growth of competing algae such as Corallina or Halosaccion, allowing Postelsia to grow freely after wave action has eliminated the mussels.

Coralline algae "Corallinales" are predominant features of mid and low intertidal tide pools. Calcium carbonate (CaCO<sub>3</sub>) takes the form of calcite in their cell walls providing them with a hard outer shell. This shell protects from herbivores and desiccation due to lack of water and evaporation. Many forms of the Coralline algae bring herbivores, such as mollusks "Notoacmea", to the tide pools during high tides, increasing the biomass of the area. Once low tides comes, these herbivores are exposed to carnivores in the areas, fueling the food web.

File:Anthopleura sola is consuming Velella velella.jpg|A starburst anemone (Anthopleura sola) consuming a by-the-wind-sailor (Velella velella), a blue hydrozoan

File:Postelsia palmaeformis 2.jpg|alt=Photo of speckled rocks, and various irregularly-shaped animals|Postelsia palmaeformis at low tide in a tide pool

File:Starfishmussel.jpg|alt=Photo of five-legged approximately radially-symmetric animal lying on rock with shelled animal in its mouth, which is in the center of its body|Sea star, Pisaster ochraceus consuming a mussel in tide pools

File:Close-up of clone war of sea anemones.jpg|Sea anemones, Anthopleura sola engaged in a battle for territory

thumb|Tide pool with several species including Coralline Algae, Corallinales (purple color).

File:Tide pool in fog at extreme low tide, Kachemak Bay.jpg|Temporary tide pool at an extreme low tide, Kachemak Bay, Alaska

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Coastal predators

Tide pools are often surrounded by coastal predators who feed on tide pool flora and fauna. These predators play an important role in the tide pool food web and create competition for resources.

References

External links

Tidal swimming pools in Britain

Fauna

Flora

Coastal predators

See also

References

External links