Most people who have been to the seaside have probably noticed small white volcanic formations. As a rule, they densely cover coastal stones and underwater fragments of various structures. These formations are the shells of various types of crustaceans.
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Today we will talk about barnacles, and they are also called sea acorns. Subclass Crustaceans. Barnacles are representatives of the following types of crustaceans:
- Thoracica - These include sea ducks and sea acorns.
- Acrothoracica are small, boring forms that live in mollusk shells.
- Apoda - zooparasites of individual members of the order Thoracica.
- Rootheads (Rhizocephala) - biophytes of decapods.
Habitat
The barnacles, of which there are about 1200 species, are found all over the world and live in the seas. The largest number of different types can be found in s alty coastal waters. The sizes of crayfish start from a height of 3 mm (in Chthalamus varieties) and reach a diameter of 70–100 mm and a height of 120–150 mm (in the genus Balanusnubilus).
Certain types of large barnacles settle only on rocks submerged in water. For example, crayfish living on the Pacific coast of the United States of America can reach a mass of 1.5 kg.
Crayfish: lifestyle
These individuals are the only ones of all their relatives who lead a "sedentary life". One of the main functions of barnacles is the ability to produce a sticky special substance that helps them stick to almost any surface. It cures quickly in a humid environment and holds up well to extreme temperatures and pressures. Sea acorns securely wrap around piles, rocks, and other hard surfaces.
Barnacles are attached to frozen objects that are submerged in water, such as the bottoms of ships in the port. They can be seen on mollusc shells, crab shells and whale skin.
Prolonged exposure to air, low temperatures or fresh water are detrimental to barnacles, but their cone-shaped shells continue to cling to the last, until they are worn off. At low tide, crayfish hide in a multi-lamellar shell, which consists of calcium carbonate.
Reproduction
The barnacle larva is part of the plankton, the initial link in the food chain. Barnacles are very prolific marine animals. A study off the northwest coast of England found that coastal crayfish produce a trillion larvae a year.
Tropical crayfish begin to breed at three weeks of age and produce about 10 thousand larvae three times a year - and so on throughout their existence (for 4-5 years).
The born crustaceans emerge from the shells of their parents and almost immediately become the food of planktivorous animals. Those who managed to survive find a new place to live in a couple of weeks. Settling on the ground, they begin to secrete a sticky substance. After a few hours, it hardens, and the final transformation of the larva into an adult cancer occurs.
Within 5-10 days, the young crayfish completely locks itself into a cone consisting of six calcareous petals overlapping each other.
Non-parasitic barnacles
Non-parasitic barnacles are divided into two main types - sea ducks and sea acorns. Their body is shrouded in a mantle, which releases calcareous plates into shells. The body of a crustacean is divided into head, thorax and belly.
Antennules (antennae) are located on the head, which in most cases serve for touch. The antennae of lower crustaceans are also organs of locomotion.
There are six pairs of two-branched legs on the chest, with the help of which the crayfish collects water with food particles - microorganisms into the mantle cavity. Shaking its legs, the crayfish attracts plankton, absorbs oxygen from the water.
These animals have no gills, and a single eye can only distinguish darkness from light. Most barnacles are hermaphrodites.
Uparasitic barnacles sac-like body, missing shell, intestines and limbs.
Sea ducks
On the Spanish, Italian and Greek coasts there is a different kind of barnacles - these are sea ducks. They cause less inconvenience than their other variety - sea acorns. Ducks are attached to floating objects, such as pieces of rotten wood. At the initial stage of development, the larvae of sea ducks and sea acorns lead the same mode of existence. When the settling period comes, they also stick in one place, but have a little more freedom in breeding and feeding.
Cleaning ships from sea acorns
Since ancient times, barnacles (pictured below) have been a problem for millions of boat owners.
Removing them from the bottoms of ships is a long and complicated process that costs millions of dollars.
In warm waters, the slowdown caused by six months of fouling forces the owner to use 40% more fuel to maintain normal speed.
Any reduction in speed results in additional costs, such as:
- cleaning the bottom of the vessel;
- buying extra fuel.
Warships become most vulnerable to enemies when barnacles are attached to the hull. They turn a warship into an object, which, due to the distortion of the echo signal, becomes easily heard by sonar instruments.
According to experts' calculations, only inThe United States of America spends millions of dollars each year to clean up fouling on the bottoms of civilian and military ships.
Bottom protection
As soon as people began to study the oceans and seas, they tried to find a remedy that prevents barnacles from attaching to ships. The Phoenicians tried to use resin. The Greeks tried wax and tar, but nothing helped until they began to use copper to coat wooden hulls.
However, for modern large ships, copper is a very expensive substance, for this reason paints that include copper oxide are currently used.
After the chemical is leached out of the paint, it forms a toxic film that protects the ship from marine animal larvae.
One of the latest is barnacle crayfish, the larva (photo above) attaches to a specific place on the vessel, subsequently forming a shell. On average, the paint protects the bottom of the vessel for three years.
The secret of the goo
Despite the fact that barnacles unnerve bathers and upset shipowners, they have attracted the interest of scientists for centuries. Charles Darwin spent over eight years of his life researching them.
Scientists believe that if the composition of the secreted adhesive substance is known, it will be possible to synthesize a similar adhesive product that could be successfully used in dentistry, orthopedics, surgery, traumatology, and also in industry.
However, the adhesive is notin a hurry to reveal their secrets. In the solid state, it cannot be dissolved either by strong acids or by organic solvents. It is resistant to bacteria and can withstand temperatures above 200°C.
Interesting facts
According to paleontologists, barnacles first appeared 400 million years ago. Since the Jurassic period, tenacity has been their main feature. Their remains from that period show the barnacles still attached to the planes they settled on 150 million years ago.
For a long time, barnacles were mollusks, and only thanks to the discovery of a free-swimming larva, it was possible to determine their relationship with other crustaceans.
Eating barnacles
Steamed crayfish tastes like crab and lobster at the same time. It is served with a special sauce made from seafood. This dish is appreciated by gourmets all over the world. Barnacles can be eaten raw or fried or boiled.
Here are such complex and peculiar marine inhabitants - barnacles.
