This mollusk has two common names: guidac and panopea. The first came from the Niskuali Indians and means "dig deeper." The second name was formed from the Latin system name of the mollusk - Panopea.
Guidak has an extraordinary appearance. The Chinese are comparing it to the trunk of an elephant. In the population of southeast Asia, panopea is associated only with food. The largest number of mollusks is caught off the coast of Canada in the Gulf of Alaska, and it is eaten mainly in China and Japan.
Description and Features
Guidac is the largest of all bivalve digging mollusks. Instances weighing from 0.5 to 1 kg are not uncommon. There are individuals weighing 7 kg. Giant guidac it has a siphon length of up to 2 m. The appendage-siphon starts at the back of the mollusk, so the name tail could be suitable for it.
The large weight of the guidac and the sedentary existence went to the clam only for the benefit. This invertebrate is one of the most long-lived creatures on the planet. Living 140 years is the norm for panopea.
Scientists discovered the long-lived guidaka and found out his age. This mollusk spent, dug in the ground, 168 years. The marine inhabitant was able to achieve such results thanks to a non-hectic lifestyle, a slowed metabolism, and the ability to hide from predators.
Guidak in the photo surprises with its remarkable organ - siphon. This part of the body connects with a tube the mantle cavity of the guidac with the outside world. More precisely, the guidaka in the siphon has two tubes. One works on input: introductory. Another provides the discharge of waste water: outlet.
Through the opening siphon, water enters the body of the mollusk. Washes his gills, reaches the oral lobes. On the blades of the guidac there are sensitive cells that allow edible particles to be recognized in the stream of water. The gills of the mollusk carry out not only gas exchange. They participate in the separation of edible and inedible.
Eatable grains are sent to the mouth, from where they enter the stomach through the esophagus. The guidac has an intestine in which the digestive process ends. Not everything that enters the body of a guidac can be absorbed by his body. Waste and inedible elements together with the waste water current are thrown out through the siphon discharge pipe.
Guidac is a bivalve mollusk. But his body is so large that it does not fit inside the sink. The shell flaps have rounded edges. They are the same in size and fastened together by an elastic ligament. The valves cannot close and fulfill their protective role only partially.
Guidaka shell, like all bivalves, consists of layers: periostracum, prismatic and pearlescent. Periostracum is an outer, especially thin layer of horny organic material of conhiolin. Which is contained in the epithelium, covering not only the shell, but also the muscular mantle and the entire surface of the siphon.
The mantle, consisting of the left and right parts, combines on the front surface, forming a muscular organ, the "stomach" of the guidac. In addition, the mantle merges with the lower, ventral part of the siphon. There is only one hole in the mantle - this is the passage for the clam leg.
The full name of the mollusk is the Pacific guidac. It enters the biological classifier under the name Panopea generosa. It is the most famous representative of the genus Panopea, which includes 10 species. The general range of the genus is fragmentary: from northwest Canada to New Zealand.
- Panopea generosa - pacific guidac. This is the type of mollusk that is implied when the name "guidac" is pronounced.
- Panopea abbreviata - south guidac. It lives in the Atlantic waters adjacent to the shores of Argentina, the so-called Argentine Sea. The mollusk has relatively modest dimensions: length no more than 15 cm, weight less than 1.3 kg.
- Panopea australis is an endemic of Australian coastal waters. The length of an adult mollusk is about 18 cm.
- Panopea bitruncata - atlantic guide. Found in the Gulf of Mexico.
- Panopea globos - guidac cortes. This species was considered endemic to the Gulf of Mexico. Recently, ichthyologists found him off the coast of the Mexican state of Baja California in the Pacific Ocean.
- Panopea glycimeris - found in the Mediterranean Sea, off the Atlantic coast of Portugal.
- Panopea japonica - japanese sea guide. Lives at shallow depths in the Sea of Japan, the southern part of the Sea of Okhotsk.
- Panopea smithae - a mollusk mastered the waters surrounding New Zealand. Maybe, unlike their relatives, to meet at great depths.
- Panopea zelandica - new zealand guidac. It lives in the coastal waters of the New Zealand islands. It can be found off the coast of Stewart Island.
In addition to the living panopea, approximately 12–13 extinct species are included in this genus. The shells and remains of these mollusks often fall into the hands of paleontologists in good condition, so much so that it is possible to accurately determine their species.
Lifestyle & Habitat
Having passed the larval stage, the mollusk settles on the ground and begins to act as an adult. This is called the stage of disunity. By the end of the second year, the guidac reaches adult size and burrows to the same depth, about 90 cm.
Guidac or panopea leads a static lifestyle. He constantly filters the water, extracting oxygen and edible particles necessary for life. With the end of winter, it moves to spawning, which lasts until mid-summer.
It is not known how the guidac feels the approach of a predator. In this case, wanting to hide better, the mollusk from both siphon tubes begins to spew water. Due to reactive power, he hides the siphon and is completely buried in the ground.
The basis of the guidaka diet is phytoplankton, primarily diatom and dinoflagellate species. Diatoms are single-celled organisms. Dinoflagellates or dinophytes are unicellular monads. Both are an essential part of plankton.
Guidak itself has been food for the local population since pre-Columbian times. Which consisted of Indians belonging to the tribes: the Chinook, the daughter-in-law and others. Over the past 30-40 years, interest in guidac has grown from zero to the scale of a serious business.
Until recently, guidacs were obtained only by catching mollusks that reached maturity under natural conditions. This is not an easy process involving divers. Guidaki are mined by hand individually. What makes clam fishing expensive.
The main connoisseurs of dishes prepared from shellfish are undoubtedly Japanese. They tried guidaka. They gave him the name of the world. Following the Japanese taste guidaka appreciated by the Chinese. The demand for mollusks began to grow rapidly.
His fishing has become profitable. As happens in such cases, the process of cost optimization has begun. Artificial breeding is the main way to reduce fishing costs. A clam farm looks pretty simple.
On the shore, in the tide zone, an uncountable number of pipes are buried. A guidaka larva is planted in each. Tidal waters supply the mollusks with food, and a plastic pipe indicates its location and prevents the mollusk from being washed off into the sea by breaking waves.
It remains to wait. Guidac does not ripen quickly. But after 2-3 years, you can get a crop of large mollusks. Success in catching and rearing guidaks inspired New Zealanders. Off the coast of New Zealand, there is a related species - Panopea zelandica. Gradually, he began to compete with the Pacific guidac or panopea.
Reproduction and longevity
For the reproduction of offspring, gametes (reproductive cells) of both sexes are required. Their contact is necessary for the formation of zygotes - embryos. But guidac - clam stationary. Does not leave its location. The rapprochement of heterosexual individuals is impossible.
The question is solved simply. With the onset of the breeding season, guidac, regardless of its gender, releases reproductive cells into the water column. Over a hundred-year life, a female panopea, aka guidac, sprays about a billion female germ cells. How much a male produces is not amenable to calculation.
At the end of winter, with the heating of water, the guidacs begin a breeding season. Its peak falls on May-June and ends in July. First, males release their germ cells into the water. Females react to their appearance. They produce about 5 million eggs. Females spend about 10 such generations in one season.
The first thing that should happen to an egg in an aquatic environment is fertilization or a meeting with a sperm. The probability of this is not great, but fertilization does happen.
After 6-12 hours, from the zygote, the union of the female and male reproductive, reproductive cells, a trochophore appears - the original floating guidaka larva. After 24-96 hours, the trochophore develops into a veliger or a sailboat. Sailing larvae drift along with other zooplankton.
After 2-10 days, the larva passes into a new state called the pediveliger, which can be translated like a larva with a foot. That is, at this stage, the leg develops in the mollusk embryo.
This organ is not as impressive as a siphon. In an adult mollusk, it is almost not noticeable. For the shape of the legs of the guidaks, they are referred to as pelecipods. This name - Pelecypoda - can be translated as topopod. It is the leg, making contractile movements, that ensures guidac self-locking.
Then metamorphosis occurs - the larva settles to the bottom and degenerates into a young mollusk. His first event in a new quality is digging into the ground. Only after this, the chances of survival of the guidac are significantly increased.
Guidaki breeding method was not chosen the most reliable. The colossal amount of gametes produced does little to correct the matter. Further life stages in larval embryos also do not look optimistic. But the process of reproduction is still going on. Its speed is calculated in a simple way.
A section of the seabed stands out. Divers count how many guides live in this area. The resulting number increases by 20% - about as many mollusks are skipped during the calculation. Commercial firms are given permission to collect 2% of the number of guides who inhabit this area.
The number of mollusks in a controlled area is periodically calculated. In such a laborious, but simple way, it turned out that for the appearance of an equivalent individual in the place it was caught, it took 39 years. In addition, for scientists, guidaki are a kind of long-term recorders. The condition of their body and shells answers many biochemical questions.
Guidaki live more than 100 years. They hide well from predators: they manage to reach sea otters, and some starfishes. Do not experience nutritional problems. But they chose an extremely inefficient method of reproduction. Nature seeks to maintain a balance in everything.
Shellfish catchers from the United States and Canada trade this outlandish product worldwide. The Japanese consume guidaka with special desire, the Chinese are not far behind them. Europeans, Australians, seeking to eat more seafood, joined the mollusk dishes.
Before the Chinese New Year, exporters requested $ 15 per pound, i.e. 454 grams. In a calmer time, export price guidaka twice as low. In Russia, specialized fish online stores offer this clam for about 2700 rubles. per kg, advertising it as an exquisite marine delicacy.
No gourmet food is prepared as simply as a dish from this clam. Often guidaka eat raw. That is, they cut a meaty siphon and eat it. This is what Koreans often do, though seasoning it with chili sauce. The Japanese flavored a raw piece of guidaka with soy sauce and wasabi. It turns out sashimi.
American aborigines originally prepared guidaka in much the same way as meat. The clam siphon is cleaned, cut into pieces. Fragments of the mollusk are beaten and fried in oil pre-salted, and pepper before being cooked. The dish is served with fried onions.
Clam dishes have a spicy taste and crispy texture. Guidak lovers are sure that they pay not only for a useful and nutritious product, but also for some pharmacological properties, especially valuable for men. The reason for this belief lies in the form of a clam.