The intertidal pond with sufficient sunlight and gentle water flow is a paradise for phytoplankton. Algae plants such as diatoms and sea cabbages proliferate in large numbers, which constitute the oxygen pump and food base of this miniature biosphere. Shellfish, echinoderms and coelenterates are common intertidal animals. Oysters attached to the reef slightly open their mouths to filter the seawater, while barnacles and anemones stretch out their tentacles and stuff plankton that we can't see with the naked eye into the middle mouth. Whether these animals fixed on the rocks can eat a big meal depends on luck. I once saw a little seahorse that died of high temperature being picked up by an anemone and dragged into its mouth, leaving only its curly tail exposed. For anemones, this is a godsend. There are fewer starfish and sea urchins. According to my observation, it seems that they are only brought to these intertidal ponds by the waves when they are injured.
Small crustaceans, like all kinds of snails, are frequent visitors to intertidal ponds. Transparent shrimps like to hide under the leaves of sea cabbage and feed on algae with slow movements; Crabs, on the other hand, like to search the bottom of the pool one by one, sweeping away tiny debris; The "flower cover" crab has a pair of flippers and can swim quickly; Snails of all kinds are never picky about food, and they eat whatever they have. These energetic marine scavengers never give up any energy, and they are also an important part of this tiny ecological circle.
In contrast, the fish here are much more lazy. In addition to the small fish trapped by the tide, most of the fish resident in the intertidal zone are lazy sea catfish and the like, which are called "Lengbaer" by the locals and "donkey's tail". These young fish several centimeters long are considered as "top predators" in a small intertidal pond. With their flat bodies and perfect protective colors, they are difficult to find when they blend with brown reefs. Once the small fish and shrimp pass by, they will strike like lightning and quickly open their "big mouths" to suck their prey into their mouths.
Uh ... Wrong.
After a few hours, the nutrients in the biosphere are almost exhausted, and the temperature and salinity are close to the endurance limit of animals. But don't worry, the rising sea water will soon turn the intertidal pond back into a part of the sea. At the same time, it will bring new food, more comfortable temperature and salinity, fierce predators and perhaps new residents. The permanent residents of intertidal ponds squeeze into the safe crevices and algae balls, waiting for the next low tide and expecting the next feast.