(27-10-08) In the heart of the seas in Indonesia, in Lembeh Strait, near the island of Sulawesi, we find a tropical paradise dedicated to the world of diving, where scientists and underwater cameras look for the most striking, unfamiliar and extravagant species.

   Coral reefs that surround the north of Lembeh Strait have a special attraction, and it is not by the state of conservation, but by the diversity of species that live in their environment. These pristine reefs are populated by all kinds of hard and soft corals, anemones and sponges of all shapes and sizes.

   It is not a lush landscape, as in other Indonesian reefs, but from the hundreds of species that live here some stand out because of their special biodiversity and above all for their social behaviour.

   We are talking about anemones, invertebrate and carnivore coelenterata, which are very simple biologically and depend on their immediate environment for their basic needs. In fact, the size of an anemone does not depend on its age, since they can be one hundred years old, but it depends on the amount of available light and nutrients in its environment, key elements for its growth.

    Anemones have poisonous tentacles like jellyfish, and they use them as deadly weapons to hunt any prey passing nearby by injecting paralyzing venom. There are some exceptions, and here it is one of the most striking examples of symbiosis between species: they are potential enemies but wise Nature associates them ... It is the story of the anemone and one of its tenants: the clown fish.

very exclusive associations

    There are about a thousand species of sea anemones, and only a dozen of them practice partnership with clown fishes, to which the anemone gives shelter in exchange for its own protection from other predators. This small group of anemones is very selective and they only allow a certain kind of clown fish of the thirty that are in the world to be their tenant.

    Either in the rocky walls or on the muddy bottom in Lembeh, the diversity of species of anemones that grows in any corner or uncovered attracts attention. We find a host aurora, defended by tiny clown fishes with yellow tail, which made fishes bigger than them stay far away from them.

    It is strange to see an adult clown fish together with young fishes patrolling between the tentacles, but we always find groups of bangai cardinal fish eating the food that the anemone expels. The brave bangais, with their impulses, control perfectly the art of dodging the tentacles of the anemone. Even, it seems that no small friction hurts them and they dare again and again to pass between the tentacles.

    Cardinal fishes relentless patrol next to the anemone, waiting for the current to bring them food. Meanwhile, the clown fishes swim from one side to another, patrolling tirelessly.

    Some species of clown fish create family unities inside the same anemone. Their eggs are deposited near the base and lie there, protected all the time by the stinging tentacles of the anemone, until fertilization. Some of the predators are the cardinals fishes: they catch the eggs that are detached and carried away by the current.

BANGAI CARDINAL FISHES: THE MOST OPPORTUNISTIC

    Bangai cardinal fishes are rhomboid-shaped. They have two extended dorsal fins and the caudal, pectoral and anal fins well developed and they are slightly flat if we saw them sideways. The male has the 2nd dorsal more elongated and the shape of the jaw is more rounded and larger in the male than in female, because the male incubate the eggs inside until birth.

    We only know one specie that lays its eggs near the stem of the anemones. When the eggs hatch, the male takes care of the young fishes in its mouth for several days, as a protective measure.

    Another incentive in the depths of Lembeh is to see the movement of anemones. They move both to defend themselves and when they catch.  They cover themselves with their mantle closed upon them, until they start to digest. Only the smallest clown fishes can be inside it during this process, whereas larger ones patrol from the outside.

    When the anemone opens its mantle, it is time for the opportunists to collect the wastes from the food the anemone has eaten. The clown fishes and the cardinal fishes fight, and also butterfly fishes, fish castanet and goby fish. It is a great spectacle...

A LESSON IN LIVING AND WORKING IN TEAMS

    A few species of anemones and clown fish teach us a lesson in living, teamwork and adaptability. In Lembeh Strait, the variety of hosts and tenants is huge and impressive; it is like jumping from one world to another in an environment that attracts because of the colour of its bottom and its species.

    But where these strange beings are more spectacular is in these walls in Lembeh Strait. Here we find new partnerships, with very special guests that in the end bring little or nothing...

    There we saw porcelain crabs that were hidden among the tentacles of anemones without any apparent exchange between them. It seemed that only the crabs profited from it: they feed on the waste of this huge blanket of tentacles and they seemed to be immune to its poison. One crab ate there until it was too close to the anemone and it was captured and eaten by the host.

    We said goodbye to this dive between anemones in Lembeh thinking that only the action of man can seriously disturb the balance of this delicate habitat of thousands of species. The observation of the marine life has to be absolutely respectful with the environment. If we get too close or we touch or just scare these tenants away, they can leave the host, whose colour has been adjusted, and get lost, homeless and prey of the first predator that they meet.