A lot of people don’t even imagine, but on the sandy beaches several marine species live hidden. They are difficult animals to see because they are very small – some even invisible to the naked eye – and because they live buried and camouflaged. “Most of the animals have a color similar to that of sand. To identify their presence, it’s easier to pay attention to the small holes in the ground and the tracks left», says biologist Álvaro Migotto, from the Center for Marine Biology (Cebimar) at the University of São Paulo (USP). Almost all major groups of marine animals such as crustaceans, molluscs and annelids are present in this ecosystem. The thousands of species that live by the sea can inhabit three different segments of the sand: the upper strip, farther from the water, which is only covered by waves at very high tides; the middle strip, reached by the tide twice a day; and the lower range, almost always submerged.
: macrofauna (animals larger than 1 millimeter), meiofauna (from 0.1 millimeter to 1 millimeter) and microfauna (below 0.1 millimeter). “Despite being invisible to us, meiofauna and microfauna animals are extremely numerous and very important in ecological and zoological terms. They live in the spaces between the grains of sand”, says Migotto. The animals best known by those who frequent the beach, however, belong to the macrofauna and measure from 2 to 20 centimeters. Among them, there are the tatuíra, the clam, the guaruçá crab, the beach biscuit, the gastropods and the corrupt. In addition to these permanent residents, the ecosystem by the sea also receives many visitors, such as seagulls and sandpipers, birds that explore the sand in search of food at low tide. At high tides, fish and crustaceans come out of the seabed to look for food on the submerged beach.
camouflaged fauna
We almost don’t see it, but many animals can be found by the seaAIR THREAT
The beings that live on the beach are constantly in the sights of some seabirds. With their thin and long beaks, sandpipers look for small crustaceans and molluscs that live buried in the sand. Seagulls, in turn, feed on fish or the remains of other organisms.
NIGHT LIFE
Due to its yellowish-white color and the habit of only leaving its burrow at night, the Guaruçá (Ocypode quadrata) is also called the ghost crab. Another of her nicknames is maria-farinha. He digs galleries in the sand, where he spends the day hidden from the sun. To avoid sea water, the galleries are located at the extreme edge of the sand, close to the coastal vegetation.
FAST ON THE ESCAPE
The tatuíra (Hipa sp.) is a very popular crustacean along the Brazilian coast and goes by different names, such as tatuí, flea-of-the-sea and armadillo-de-beach. It measures about 4 centimeters and lives in holes dug in the sand. Fast, the tatuíra burrows quickly when the wave water returns to the sea, leaving it unprotected
APPETIZING MOLLUSC
The clam (Tivella mactroides) is one of the many bivalve molluscs — with a shell formed by two symmetrical pieces — that inhabit the beaches. Unlike the mussel, which sticks to the rocks, the clam prefers to live in the sand of almost muddy beaches and without very strong surf. The little animal is very popular in coastal cuisine.
CORRUPT ANONYMOUS
Living in burrows deep in the sand and rarely seen, the Corruptos are a type of crustacean that is subdivided into more than 90 species. Some of them measure a few millimeters, but there are those that reach about 30 centimeters! The corrupt feed on organic remains and small animals that enter their galleries.
BUSY SHELL
Gastropods form the most numerous group of molluscs. Snails, whelks and sea hares are the best known types of marine gastropods. Most of them have a spiral-shaped shell, inside which the animal’s body is housed. It is with these shells that, when abandoned, people believe they can hear the sound of the sea.
POINTLESS STAR
The sea urchin (Encope emarginata) belongs to the echinoderm phylum, which includes animals such as sea urchins and starfish. It has an internal calcareous skeleton that normally remains intact after the animal’s death and can be found lying on the beach, among empty shells and other remains of animals and plants.
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– How did beach sand form?
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