Cute Young Brunette Girl Wearing Necklace On The Sandy Shore Posing With A Colorful Scarf

Functioning and adaptations
The intertidal zone is covered part of the day by water and is part of the day exposed to air. High tides bring nutrients and food with it. When the tide retreats, waste products, eggs and larvae are taken. This causes changes for the organisms that live there. They have adapted to this changing environment, as seen on rocky shores.
The burrowing must be rapid and powerful on high-energy sandy beaches. This is because the animals must not be swept away by incoming waves and swash. They also need to be high mobile and must be able to deal with the swash climate. In contrast with rocky shores, desiccation is not an overriding concern, because the animals can retreat into the substratum or below the water table. Intertidal filter-feeders cannot feed while the tide has retreated. Many species of the meiofauna use vertical tidal migrations through the sand column. Other species move up and down the beach with the tides. This is inadequate for the maintenance of appropriate rhythmic behavior so responses to changing environmental factors are essential. There is a difference between directional (such as light, slope of the beach, water currents) and nondirectional (such as disturbance of the sand, changes in temperature, hydrostatic pressure) stimuli. Directional stimuli act as orientational signs, while nondirectional stimuli act as releasing factors. Because of the absence of attached macrophytes, the predominant feeding types are filter-feeding and scavenging. Adaptations to respiration of animals in low-energy sandy beaches are different from those on surf-swept beaches. Some adaptations are an increased ventilation rate or increased efficiency, reduced metabolic rate or other ways of conserving energy. Many sheltered-shore animals are facultative anaerobes. This is an adaptation during ebb tide. Other animals in oxygenated surf-swept beaches are essentially aerobic. The majority of the intertidal animals have tolerance levels of natural variables that exceed those necessary for survival in their particular habitats. Some species descent into the burrow to escape high temperatures. Another solution is evaporative cooling by replacing water through entering the burrow, plunging into the sea or absorption from the substratum. Another problem for intertidal animals is the time of reproduction. There is variation in the number of eggs, the anatomy of the reproductive organs, the morphology of the egg cases, times of breeding, mating behavior and developmental stages. Adaptations for this is to reproduce at frequent times (iteroparous) or to reproduce just once in a year (semelparous). This depends from species to species. Some species follow the lunar cycle to reproduce at the right time. To ovoid predation, several behaviors are developed. The first one is to burrow very deep. Another one is tidal migration, so the animals remain protected from predation. Other responses are escaping movements or an impressive threat display by crabs by holding their chelae open and aloft. According to circumstances, the behavior of the animals can be modified. This is called phenotypic plasticity.