Most people who have been on the seashore most likely paid attention to small snow-white volcanic formations. They, as a rule, densely cover coastal stones and underwater fragments of various structures. These formations are shells of various types of crustaceans.
Kinds
Today we’ll talk about the barnacle’s crayfish, and they’re also called sea acorns. Subclass Crustacean. Barnacles are representatives of the following crustacean species:
- Thoracica - these include sea ducks and sea acorns.
- Acrothoracica are small boring forms that live in mollusk shells.
- Apoda - zooparasites of individual representatives of the order Thoracica.
- Root-headed (Rhizocephala) - biophytes of decapods.
Habitat
Barnacles, which number about 1200 species, are found all over the world and live in the seas. The greatest number of different types can be found in salty coastal waters. Crayfish sizes start from a height of 3 mm (in varieties of Chthalamus) and reach a diameter of 70–100 mm and a height of 120–150 mm (in the genus Balanus nubilus).
Certain species of large barnacle crayfish settle only on rocks immersed in water. For example, crayfish living on the Pacific coast of the United States of America can reach a mass of 1.5 kg.
Barnacles: lifestyle
These individuals are the only ones of all their congeners who lead a "settled life". One of the main functions of the mustache is the ability to produce a sticky special substance that helps them stick to almost any surface. It hardens quickly in a humid environment and is firmly held at extreme temperature and pressure. Sea acorns reliably braid piles, stones and other hard surfaces.
Barnacles are attached to frozen objects that are submerged in water, for example, to the bottoms of ships located in the port. They can be seen on mollusk shells, crab shells and whale skin.
Prolonged exposure to air, low temperature or fresh water is fatal to the barnacle, but their conical shells cling to the last until they are worn out. At low tide, the crayfish hide in a multi-plate carapace, which consists of calcium carbonate.
Breeding
The larva of the barnacle cancer is part of plankton, the original link in the food chain. Barnacles are very prolific marine animals. Studies on the northwestern coast of England have revealed that crayfish that inhabit the coastline produce a trillion larvae per year.
Tropical crayfish begin to breed at three weeks of age and produce about 10 thousand larvae three times a year - and so throughout their existence (over 4–5 years).
Born crustaceans emerge from the shells of their parents and almost immediately become food for planktonivorous animals. Those who managed to survive in a couple of weeks find themselves a new place of residence. 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 adult cancer occurs.
Within 5-10 days, the young cancer completely locks itself in a cone, consisting of six calcareous petals overlapping each other.
Non-parasitic barnacles
Non-parasitic barnacle cancers 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 crustaceans is divided into the head, chest and belly.
Antennulas (antennae) are located on the head, which serve in most cases for touch. Antennae in lower crustaceans are also organs of movement.
On the chest there are six pairs of bifurcated paws, with the help of which the cancer collects water in the mantle cavity with food particles - microorganisms. Shaking its legs, the cancer attracts plankton, absorbs oxygen from the water.
These animals lack gills, and a single eye is able to distinguish only darkness from light. Most of the barnacle cancers are hermaphrodites.
The parasitic barnacle has a saccular body, there is no shell, intestines and limbs.
Sea ducks
On the Spanish, Italian and Greek coasts, a different type of barnacle crayfish is found - 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, larvae of sea ducks and sea acorns lead the same way of existence. When the precipitation period begins, they also stick in one place, but have slightly more freedom when propagating and feeding.
Cleaning ships from marine acorns
Since ancient times, barnacle crayfish (the photo of which is presented below) have been the problem of millions of ship owners.
Their removal from the bottoms of ships is a long and complex process, during which millions of dollars are spent.
In warm waters, the slowdown caused by six-month fouling causes the owner to spend 40% more fuel to maintain the normal speed.
Any reduction in speed leads to additional costs, such as:
- cleaning the bottom of the vessel;
- purchase of additional fuel.
Military vessels become the most vulnerable to enemies in the event of attachment of barnacle crayfish to the hull. They turn a warship into an object, which, due to distortion of the echo signal, becomes easily audible by hydroacoustic devices.
According to experts, in the United States alone, millions of dollars are spent annually to clean up fouling on the bottoms of civilian and military courts.
Ship bottom protection
As soon as people began to study the oceans and seas, they tried to find a tool that prevents the attachment of barnacle crayfish to ships. The Phoenicians tried to use the resin. The Greeks tried wax and tar, but no means helped until they began to use copper to coat wooden cases.
However, for modern large vessels, copper is a very expensive substance, for this reason paints, which include copper oxide, are currently used.
After leaching a chemical from the paint, it forms a toxic film that protects the vessel from the larvae of marine animals.
One of the latter is a barnacle cancer, the larva (photo above) attaches to a specific place in the vessel, subsequently forming a shell. On average, paint protects the bottom of the vessel for three years.
Mystery of the goo
Despite the fact that barnacles irritate bathers and upset shipowners, they have attracted the interest of scientists for centuries. Charles Darwin spent more than eight years of his life researching them.
Scientists believe that if you know the composition of the emitted adhesive substance, it will be possible to synthesize a similar adhesive product that could be successfully used in dentistry, orthopedics, surgery, traumatology, as well as in industry.
However, the sticky substance is in no hurry to reveal its secrets. In the solid state, it cannot be dissolved either with strong acids or with organic solvents. It is not affected by bacteria and can withstand temperatures above 200 ° C.
Interesting Facts
According to paleontologists, barnacle cancers first appeared 400 million years ago. Starting from the Jurassic period, their main sign was tenacity. Their remains dating back to that period show the barnacles still attached to the planes on which they settled 150 million years ago.
For a long time, the barnacles belonged to mollusks, and only thanks to the discovery of a free-floating larva did they manage to determine their relationship with other crustaceans.
