Some species adapt by reproducing frequently iteroparous or by reproducing just once in a year semelparous. There are also species that follow the lunar cycle to reproduce at the right time. To avoid predation, several behaviors have developed. The first one is deep burrowing. Another one is migration with the tide to escape predation. Crabs impress predators by holding their chelae open and aloft. According to circumstances, animals can modify their behavior.
This is called phenotypic plasticity. Several groups of vertebrates make use of sandy beaches for foraging, nesting and breeding. Turtles nest on the backshore of sandy beaches. Birds use the beach for foraging, nesting and roosting. Seals use several areas of the beach for nesting, molting, breeding and raising pups. Other terrestrial animals such as otters, baboons, raccoons, lions,… may descend onto the beach to forage.
The distribution and abundance of the sediment infauna is mostly controlled by complex interactions between the physicochemical and biological properties of the sediment. Most invertebrate phyla are represented on sandy beaches, either as interstitial forms or as members of the macrofauna [4].
The macrofaunal forms are by far the better known. Some of them are typical of intertidal beaches and the surf zone, while others are more characteristic of sheltered sandbanks, sandy muds or estuaries and are less common on open beaches of pure sand [4].
Macrofauna of sandy beaches are often abundant and, in some cases, attain exceptionally high densities. The main feature is the high degree of mobility displayed by all species. These animals may vary from a few mm to 20 cm in length. The macrofauna community consists of organisms too large to move between the sand grains.
The macrofauna of sandy beaches includes most major invertebrate taxa although it appears that molluscs, crustaceans and polychaetes are the most important. Crustaceans are usually more abundant on tropical sandy beaches or on exposed beaches whereas molluscs are more abundant on less exposed and on temperate beaches. However, there are many exceptions and polychaetes are sometimes more abundant than either of these taxa. Crustaceans generally dominate the sands near the upper tidal beach and molluscs near the lower beach [4].
Physical factors, primarily wave action and sediment grainsize largely determine the distribution and diversity of the invertebrate macrofauna of sandy beaches. Food supply and productivity in the nearshore zone are important for the population abundance. In contrast to the swash-swept beach surface inhabited by most of the macrofauna , the interstitial system is truly three-dimensional and often extends deep into the sand.
Its inhabitants include small metazoans forming the meiofauna , protozoans, bacteria and diatoms [4]. The meiofauna is defined as those metazoan animals passing undamaged though 0. On most beaches the interstitial fauna is rich and diverse, even exceeding in some cases the macrofauna in biomass [4]. The dominant taxa of sandy beach meiofauna are nematodes and harpacticoid copepod, together with other important groups including turbellarians, oligochaetes, gastrotrichs, ostracods and tardigdades.
See Latitudinal biodiversity patterns of meiofauna from sandy littoral beaches for a more detailed description of the latitudinal biodiversity patterns of meiofauna on sandy beaches. Terrestrial insects and vertebrates are frequently overlooked in accounts of sandy beaches. Although harvest limits are low and populations in most sandy beaches are not large enough to support extensive harvesting, clams are harvested both recreationally and commercially for food.
On many Southern California shores, the upper beach is disappearing and along with it at least two of its denizens: Tylos punctatus and Alloniscus perconvexus. These isopods aka roly polies , unlike many critters that live lower on the beach, do not live in the ocean for any part of their life cycle nor can they move long distances as adults.
If their habitat is lost they are unable to move to a new location. Generally, beaches where these roly polies are found are home to a list of species with similar life histories and vulnerable to decline; thus, suggesting these isopods are a good indicator of beaches with high biodiversity and other rare species. There have been local extinctions of these beach-dwelling crustaceans at many beaches in Southern California, especially in Santa Monica Bay and Orange County.
When considering the future impacts of climate change on sandy beaches, the eastern end of the Santa Barbara littoral cell may offer one of the best opportunities for the survival of populations of these increasingly vulnerable beach creatures. Twelve kilometers of mostly undeveloped shoreline provides the rare possibility for shoreline retreat in Southern California.
Learn about the consequences of beach nourishment. Skip to main content. Life on the Go The intertidal zone of the sandy beach and its mobile inhabitants are incredibly dynamic. Sand Dwellers Move All over the Beach. Spadefoots stock up on food for the rest of the year at this time as well, and, following the rains, move back into sandy tunnels and dens to hibernate. Fringe-toed lizards have long, pointed toes covered by scales that look like fringe. These lizards are able to run quickly over sand, and they also burrow deeply into it to create homes where the temperatures can be as much as 50 F cooler than outside.
Their eyelids and jaws have adapted to keep sand out, and they hunt at night for smaller animals and insects that also live in the sand. Ant lions are insects shaped like arrowheads with long pincers at their wider end. What Kind of Wildlife Live in the Deserts? Animals in the Tropical Desert. Sidewinder Snake Facts.
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