Marine plants are autotrophs, which use chlorophyll for photosynthesis and produce organic matter in the ocean. Marine plants belong to primary producers, with a wide variety, ranging from lower eukaryote-free algae (Cyanophyta and Prochlorophyta) to eukaryote-containing Rhodophyta, Phaeophyta and Chlorophyta, and even higher seed plants, with a total number exceeding 13.
seaweed
The morphology of marine plants is complex, ranging from a single cell Chlorella with a size of 2 ~ 3 microns to a multicellular giant brown algae with a length of more than 60 meters. There are simple groups, filaments, and trees with complex structures such as vascular bundles and embryos. All the plants in the ocean are called seaweeds, and some seaweeds are so small that they need to be magnified by a microscope for dozens or hundreds of times to see them. They are composed of a single cell or a string of cells, with different colors of branches and leaves, which float in the water. The growth and reproduction speed of unicellular algae is very fast, which can be increased many times a day. Although it is constantly swallowed by all kinds of fish and shrimp, the number is still huge.
Large algae are tens or even hundreds of meters long. Their soft bodies cling to the bottom of the sea and are shaken back and forth by the waves, but they are not easily broken. The economic value of seaweed is very high, such as kelp, laver and seaweed in China's shallow sea, which are all good foods, and some of them can also extract industrial raw materials and medical raw materials such as iodine, bromine and potassium chloride.
Seaweed is the food of marine animals. Some marine animals are herbivores, while others live by eating herbivores. Therefore, most marine animals feed on seaweed.
Seaweed, like plants on land, cannot live without sunlight. Marine green plants absorb nutrients from seawater and synthesize organic matter (sugar, starch, etc.) during their life. ) meet the needs of marine plants through photosynthesis under sunlight. Photosynthesis must have sunlight, but sunlight can only penetrate into the surface of seawater, which makes algae only live in shallow water or the surface of the ocean, and large algae can only live in the seaside and the seabed with a water depth of tens of meters.
Seaweed, like plants on land, cannot live without sunlight.
Marine plants are mainly algae. Seaweed is a simple photosynthetic organism with complex morphological structure, lifestyle and evolution process. They are between photosynthetic bacteria and higher plants-vascular plants, and play an extremely important role in the origin and evolution of organisms. There are not many kinds of marine seed plants, all of which belong to angiosperms, and there are no gymnosperms. Usually divided into mangrove plants and seaweed. They form a coastal biological community with various organisms.
Marine plants also include a kind of symbiotic algae and bacteria-marine lichen. There are not many kinds, which are more common in intertidal zone, especially in supratidal zone; The Atlantic coast is more than the Pacific coast. Marine bacteria and marine fungi traditionally belonging to marine plants have been separated with the separation of bacteria and fungi.
seaweed
Algae are lower autotrophic plants containing chlorophyll and other accessory pigments. Plants can be divided into three types: single cell, single cell population and multicellular. Algae has no real difference between roots, stems and leaves, and the whole plant is a simple thallus. All parts of algae have the function of making organic matter, so algae is also called thallus. Seaweed is the main body of marine plants and a great natural wealth of human beings. At present, there are more than 100 kinds of algae that can be used as food.
Algae grow in the shallow sea area below the low tide line, where the ocean meets the land, where the impact of waves is relatively mild, the seawater is rich in minerals, and there is plenty of sunshine. Therefore, both red algae and brown algae, although different in color, contain chlorophyll, which can be used by sunlight for photosynthesis, and the oxygen released during photosynthesis is indispensable for animals to breathe; Seaweed plays an important role in making the marine world so colorful and lively.
There are different kinds of seaweed because of its shape, color and posture, among which laver, kelp (kelp bud), kelp and red hair are often used in cooking. At present, there are about 2300 species of algae, and the size and shape of algae vary greatly. The smallest algae, such as unicellular unicellular algae, are only 5 ~ 25mm long, and there are kelp as long as 300m, which can circle the house several times. Some are balls, tubes, filaments or membranes. At high tide, seaweed floats with the current of seawater, like clusters of marine forests, and it is also a nursery for fish, shrimp and shellfish. At low tide, seaweed hangs on the rock surface, looking miserable. They are such lovely marine plants.
Algae vary greatly in size and shape.
Seaweed has no roots, stems, leaves and other tissues.
Although seaweed is similar to ordinary plants, it actually does not have the basic structure of plants, such as roots, stems, leaves and other tissues. The roots of seaweed only have a fixed function, but have no function of absorbing nutrients. The stem-like structure growing from the fixed part is called petiole, which is supported by the buoyancy of seawater, so according to the ecological habits of algae, algae must have a stable base to attach.
Scientists named algae according to a certain color system in the solar spectrum absorbed by algae. Green algae growing in shallow water will absorb the red spectrum, and the species of green algae include Lithocarpus, Ulva, Sphagnum and so on. Red algae can absorb blue light. Red algae include laver, cauliflower and cockscomb. Brown algae is between red algae and green algae, and the most common ones are kelp and Undaria pinnatifida. Besides being used as food, algae can also produce oxygen. 50% of the oxygen in the atmosphere is released through photosynthesis of algae, which is closely related to the living environment of human beings.
All algae contain chlorophyll in spite of different colors.
Algae, like ordinary higher plants, play the role of primary producers in the ecosystem and are food sources for fish, shrimp and so on. Humans also regard it as an important nutritional ingredient. The jelly of watercress, a holy product for relieving summer heat, takes seaweed extract "watercress" as jelly. All kinds of seaweed that children are keen on are made of seaweed, and the black skin of Japanese sushi is a must for making seaweed. In recent years, many health-care and blood-enriching foods, fertilizers, medicines and even industrial oil are based on seaweed. Will such a big demand run out of raw materials?
Although there are many natural enemies of algae, its vitality is still quite strong, because after the death of algae adults, they can still grow new buds to replace dead individuals, or germinate from spores, so that life can multiply indefinitely. In addition, the artificial culture methods tested in recent years should ensure that there is no danger of shortage of seaweed.
If you know the nutritional value of these seafood, you will cherish these marine benthos more. According to the "Table of Nutritional Components of Common Seafood Foods in Taiwan Province Province", laver is very rich in nutritional components, with a high content of protein, which is higher than chicken, eggs and pork. Iron content is also very high, more than 8 times higher than chicken liver, pig liver and beef liver. The calcium content is more than 7 times higher than that of milk.
The nutritional components of kelp are different from seaweed, which can prevent cancer, which is related to its high selenium content.
Although the whole Undaria pinnatifida is soft, only the tender leaves are picked and dried for sale. Undaria pinnatifida, which is common in the market, has a gray surface and brown leaves, but it is green after cooking. Its function is the same as seaweed and kelp.
Marine seed plants
Marine seed plants are higher plants that can blossom and bear fruit in the ocean. There are not many species, only mangrove plants and seaweed, generally excluding salt marsh plants.
Mangroves are unique woody plants on tropical and subtropical beaches. They often form trees or shrubs of different heights to form mangroves. Shallow sea bays and estuaries with relatively calm wind and waves, deep silt deposition and submerged by tidal water are most suitable for mangrove growth.
mangrove
Mangrove plants grow in special habitats for a long time, and have a series of characteristics in morphological structure: ① There are special roots that resist wind and waves and adapt to soft and anoxic mudflats, such as column roots, slab roots, olive roots, water breathing roots and aerial roots; There is abundant ventilation tissue in the cortex and a thick cork layer around it. ② Fetal eruption. The seedlings germinate in the mother fruit, and the embryo body is elongated into a rod. When they mature and land, they float on the water, and some plunge into the mud beach to settle down. (3) The cuticle of the leaf is thickened, and the stomata are depressed and confined to the lower part of the leaf; There is water storage tissue, and the vein tip expands into water storage tube cells; There are feldspar cells or phloem mechanical cells between palisade tissue cells, and there are few intercellular spaces in leaves. There are tannin-containing cell layers outside the upper and lower cortex, hairy lower epidermis and salt gland system on the upper surface, which can secrete salt to adapt to the physiological drought of saline habitats. (4) Bark is rich in tannin, up to 20% ~ 30%, to enhance the ability of resisting seawater erosion.
So far, the number of families, genera and species of mangrove plants in the world is not completely consistent. This is because there are different views on whether some plants growing on the edge of mangrove swamp and on both sides of the river where tides occasionally reach belong to mangrove plants. According to the statistics of American C.J. Dawes in 198 1 year, there are 80 known mangrove plants in the world, belonging to 18 family, 23 genera and 80 species, belonging to dicotyledonous plants and monocotyledonous plants respectively. The largest distribution center is in Southeast Asia, with 65 species, while there are few species on the east and west coasts of America and West Africa, with 1 1, 9 and 9 species respectively.
Mangroves are unique woody plants on tropical and subtropical beaches.
At present, there are 30 species of mangrove plants in China, belonging to 16 family 19 genus, distributed in Guangxi, Guangdong, Taiwan Province and Fujian provinces. There are many species in Hainan Island, including 28 species, belonging to 15 family, which gradually decreases northward. There are only 6 families and 7 species in Fujian, and only 1 species in Fuding, Fujian. To the north of Fujian, the climatic conditions are not suitable for the growth of mangroves. Mangrove plants in China are mainly Bruguiera gymnorrhiza, mangrove, acacia and Kandelia candel. At present, the highest mangrove plants in China are lotus of mangrove and Sonneraceae, reaching as high as 15m. Mangroves at the southernmost tip of Sanya, Hainan Island; The northernmost are Danshui in Taiwan Province Province and Fuding Kandelia candel in Fujian Province; The most widely distributed shrub is paulownia (also called candle fruit).
Seaweed is a monocotyledonous plant, which lives in shallow coastal waters in tropical and temperate waters and often forms sea meadows in shallow coastal subtidal waters. They have important ecological functions, and their biological productivity is the highest in tropical oceans.
In order to adapt to the living environment, seaweed also has some corresponding characteristics in morphological structure: ① There are well-developed rhizomes (horizontal stems), which enable individuals to interweave and grow on the attachment base to consolidate the implants, and then form seaweed grassland. (2) The blades are soft, banded or cylindrical in cross section, so as to keep upright when seawater flows; There are regularly arranged air cavities inside the blades, which are convenient for floating and gas exchange. (3) Flowers are inserted at the base of leaves, and stamens (anthers) and pistils (styles and stigmas) are higher than petals; Pollen is generally in the form of beads, combined into chains, and receives pollen through the flow of seawater.
Seaweed is widely distributed in the world.
Algae belong to swamp order, and 49 species of 12 genus are known, belonging to two families: ① POTAMOGETON POTAMOGETON with slender pollen grains. Include Sargassum, Sargassum, Heterophyllum, Dictyophora, Algae, Conifer, Wedge and Cladosporium. (2) The pollen grains of Myrtaceae are spherical. Including Acorus calamus, Thalia and Haloxylon ammodendron.
Algae with large leaves
Seaweed is widely distributed in the world, including 7 genera in tropical zone and 5 genera in temperate zone. Three-quarters of the species are distributed in the Indian Ocean and the western Pacific Ocean, and some species are distributed in the Caribbean Sea and the Pacific coast of Central America. There are only 1 genera in the Atlantic coast of Europe and 2 genera in the Mediterranean. There are 8 genera of seaweeds along the coast of China, among which 6 genera are warm-water seaweeds, such as Neosinocalamus affinis, Neosinocalamus, Dictyophora dictyopteris and conifers, which are found in the coastal areas of Guangdong and Guangxi. Shrimp-shaped algae and Zoysia japonica belong to warm water, mainly distributed in the coastal areas of Liaoning, Hebei and Shandong, and Zoysia japonica extends southward to the coastal areas of China, Fujian and Hongkong.
Algae have formed vast sea meadows in some coastal waters. Because of the abundance of humus and plankton in this area, it has become an excellent breeding ground for young shrimp and fish, and it is also conducive to the habitat of some seabirds. A large number of algae farms in northern Europe died of fungal diseases, which affected the survival of seabirds, attracted the attention of the scientific community and organized rescue. Hay such as kelp and shrimp-like algae are good thermal insulation materials and sound insulation materials, which can be used in construction industry.
Submarine forest
Submarine forest is a rare mangrove tree species in the world. This mangrove growing on the seabed is uneven in height, up to 5 meters. They emerge from the beach at low tide and are swallowed up by the sea at high tide. Only the taller ones show their heads slightly, and all kinds of birds rest in the treetops as the waves shake. Egrets, herons and black-tailed gulls are frequent visitors here. Turtledoves have also built nests in tall trees for many years. There are 6 species of trees in 5 families in the undersea forest. Their roots are particularly developed, intertwined and intertwined, which is of great ornamental value. There are 680 kilometers of coastline along the coast of Zhangzhou, Fujian, and mangrove resources are extremely rich. There are thousands of acres of mangroves at the mouth of Zhangjiang River in Yunxiao County, Zhangzhou City.
mangrove
Mangrove is a forest growing in seawater, and it is a unique forest vegetation growing in intertidal zone of tropical and subtropical coasts and estuaries. Their roots are well developed and twined on the beach. At high tide, they are submerged by the sea, or just show their green crowns, as if holding up a green umbrella on the sea. When the tide recedes, it becomes a lush forest.
mangrove
Mangrove coast is mainly distributed in tropical areas. The east and west coasts of South America, the West Indies and the west coast of Africa are the main areas where mangroves grow in the western hemisphere. In the east, Sumatra Island in Indonesia and the west coast of Malay Peninsula are the central distribution areas. Mangroves grow along the Bay of Bengal-India-Sri Lanka-Arabian Peninsula to the east coast of Africa. Mangroves along the coast of Australia are also widely distributed. Indo-Philippine-Indo-China Peninsula is also distributed in the coastal areas of Guangdong, Hainan, Taiwan Province and Fujian. Due to the influence of Kuroshio warm current, the mangrove coast has been distributed to Jiuzhou, Japan.
Mangroves are mainly distributed in tropical areas.
China's mangrove coast is best developed in Hainan Province, with many kinds and a wide area. There are many kinds of mangrove plants, including shrubs and trees. Because its bark and wood are reddish brown, it is called mangrove and mangrove. Mangrove leaves are not red, but green. The leafy mangroves form a green barrier along the coast. Mangroves grow on beaches. There are almost no other plants here, only mangroves resist the wind and waves, forming a unique mangrove coast.
Mangroves can absorb water and nutrients from swamp saline-alkali soil.
Mangroves have physiological characteristics of high osmotic pressure. Because of high osmotic pressure, mangroves can absorb water and nutrients from swamp saline soil, which is an important condition for mangrove plants to take root and grow in beach saline soil. The roots of mangroves are divided into columnar roots, tabular roots and respiratory roots. A mangrove tree has more than 30 pillars. Just like the most stable tripod structure for supporting objects, these pillars support the trunk from different directions, making mangroves stand up to the wind and waves. This mangrove forest plays an important role in protecting coastal stability. For example, during the devastating storm in Florida in 1960, thousands of mangroves in coastal areas were destroyed, but rarely uprooted.
The respiratory roots of mangrove plants, as the name implies, play a role in respiration. In the swamp environment, the air in the soil is extremely scarce. In order to adapt to this anoxic environment, the respiratory roots of mangrove plants are extremely developed. The respiratory roots are rod-shaped and knee-shaped. Some are slender, with a diameter of only 0.5 cm, while others are stout, with a diameter of 10 ~ 20 cm. The flat roots of mangrove plants are developed from respiratory roots. Plate roots are beneficial to the respiration and support of mangrove plants. The special function of mangrove root system enables it to grow when it is submerged by water at high tide. Mangrove plants adapt to their growing environment with such a complex and rigorous structure. The seeds of mangrove plants germinate on the mother tree after maturity. When the seedlings mature, the seedlings leave the mother tree and fall into the soil due to gravity. This viviparous phenomenon is rare in the plant kingdom. Even more surprising, the seedlings fell into the mud and took root and sprouted in the mud a few hours later. Sometimes the seedlings falling from the mother tree lie flat in the soil, and they can also grow roots and take root in the soil. When the seedlings fall into the water, they drift with the current. Sometimes wandering in the sea for months, or even up to a year, failed to find the soil it needed to grow. But once you meet the right soil, you will immediately take root and grow sturdily. Mangrove leathery leaves can reflect light, and the pores on the leaves are hollow and fluffy, which can reduce evaporation at high temperature, so they have the ecological characteristics of drought tolerance. Salt-discharging glands on its leaves can remove salt from seawater. In addition to embryo germination, mangrove plants also have the ability of asexual reproduction, that is, germination. After they were cut down, new plants soon sprouted on the base stem.
Lush red, brown and green algae
On the fertile coast of the ocean, after low tide, some plants with large leaves are often covered on the rocks on the shore, and they are connected together like huge carpets; After the high tide, these plants scattered again, suspended in the sea, swaying with the waves, much like dense green curtains in the fields. These plants are algae, which are multicellular algae that live on the bottom of the sea, as opposed to unicellular algae that drift with the current, so they are also called sedentary algae.
brown alga
There are many kinds of sessile algae, which are often colorful in dense places. Some are like Jiangnan, where the spring breeze blows green, showing a green color; Some are like frost leaves dyed in autumn, and the red ones are like flowers in February; Some are like glass begonia, which is brown. This green one is called green algae, which is green because its cells contain chlorophyll a and chlorophyll b; Red is red algae, and the cells contain chlorophyll a and chlorophyll d; Brown is called brown algae, and its cells contain chlorophyll a and chlorophyll c, which are the mixture of these two kinds of chlorophyll.
Brown algae is the largest and most complex sedentary algae. Kelp floating like colorful silk, Sargassum in ponytail, and giant algae 50 meters long are all brown algae. According to records, when Columbus was sailing in the Atlantic Ocean, he suddenly saw a calm area ahead, thinking that he had reached the mainland and was ecstatic. He took a closer look, and it turned out to be a piece of seaweed. The crew fought nervously for several days and nights before they got out of this algae sea. This is Sargassum, and Na Pianhai was named the sargasso sea from now on.
Pick up a kelp and you will see a root-like part at the bottom. This root-like part is called a fixer. It acts like an anchor of a ship, which can firmly fix the algae on the rocks at the bottom of the sea. Kelp also has a trunk like a plant stem with broad leaves on both sides. The trunk part can support the leaves and make them float upwards, which is beneficial to receive sunlight, but its strength is not enough to lift the leaves out of the water. The leaves of kelp are wide, which is beneficial for it to receive more sunlight.
Large brown algae
On the surface, sessile algae, like plants on land, have roots, stems and leaves, but in fact they are fundamentally different. Terrestrial plants, rooted in the soil, absorb water and nutrients and transport nutrients to all branches and leaves through their stems; However, algae have not yet formed this special pipeline to transport water and nutrients. It can be said that its whole body is a "mouth", and it absorbs nutrients from the water by the whole leaf. The leaves of trees, flowers and plants all have anti-surfaces, but the colors and functions of the two surfaces are different, while the leaves of algae have no anti-surfaces, and the whole algae body, including stems and fixators, can carry out photosynthesis. Some large brown algae often have a lot of air sacs on both sides of their leaves or stems in order to make their leaves spread upwards to receive sunlight better. Airbags are filled with nitrogen, oxygen and carbon dioxide. They also reduce the proportion of leaves like balloons and float in the blue ocean forever.
There are two stages in the life history of brown algae, which is usually called generational alternation. The leaves we usually see are called sporophytes, because there are countless sacs called sporangia on them, which are filled with germ cells called spores. During the reproductive period, the sporangium breaks, and a large number of swimming spores with flagella activity rush out and swim to the bottom of the sea, slowly growing into small gametophytes. This gametophyte has a female and a male, and the male gametophyte produces motile sperm, which swims to the immobile egg produced by the female gametophyte, and the two combine to form a zygote, which will gradually develop into a new seaweed.
There are more than 1500 species of brown algae, most of which live in the ocean, and only 1% species live in fresh water; There are more than 4 100 species of red algae, 95% of which live in the ocean, such as laver and red algae. Perhaps because of the rush to develop on land, only 15% of 6,000 ~ 7,000 kinds of green algae are still attached to the sea surface, such as Enteromorpha, reef membrane, Ulva, etc., and the rest have gone to fresh water. No wonder it became the ancestor of terrestrial plants. There are 463 species of red algae, 0/65 species of brown algae and 207 species of green algae in China, accounting for18 of the world. Red algae don't need high light intensity, so they can survive in the water depth of 250 meters, and brown algae disappear below 50 meters, so red algae often appear in the shadow of large brown algae. Red algae are most widely distributed in tropical waters. Because it can secrete calcium carbonate, it plays an important role in the formation of coral reefs.
Giant algae
Many seaweeds are delicious food and have been eaten in China for thousands of years. As we all know, eating kelp regularly will not cause coarse neck disease (goiter) because it is rich in iodine (its iodine content is100000 times higher than that of seawater). In addition to iodine, seaweed also contains many other nutrients, which is an important edible industrial raw material and has a wide range of uses. Therefore, large-scale artificial seaweed culture has been carried out in coastal areas of China, and the level of kelp culture in China is among the best in the world at present.
Seaweed also contains a lot of potassium. During World War II, Germany imposed a potash embargo on the United States, forcing American scientists to extract potassium chloride from giant algae to produce fertilizer and gunpowder. During the war, California alone harvested1500,000 tons of giant algae from the ocean. At present, people also extract phycobiliprotein from seaweed to make medicines, adhesives, stabilizers, emulsifiers, cosmetics, tooth fillings, soaps and so on.
These macroalgae are not only the producers of marine organic matter and the basis of food chain, but also important marine resources.
sargasso sea
The sargasso sea, also known as Sagaso Sea (meaning Portuguese grape fruit), is a sea with no coast in the Atlantic Ocean, roughly between 20 ~ 35 degrees north latitude and 35 ~ 70 degrees west longitude, with an area of about 5 million ~ 6 million square kilometers. The sargasso sea is surrounded by Bermuda and has nothing to do with the mainland, so although it is called "sea", it is actually not a sea in a strict sense, but can only be said to be a special water area in the Atlantic Ocean.
sargasso sea
The sargasso sea is a "sea in the ocean", and its west is separated from the North American continent by a vast sea area. The other three sides are vast oceans. Therefore, it is the only sea in the world without a coast, so there is no clear coastal demarcation line.
Sargassum, a large number of floating plants in the sargasso sea, belongs to Sargassum of Phaeophyta, which is the largest algae and the only one that can grow autonomously in open water. This plant does not grow in coastal rocks and nearby areas, but floats in the ocean in the form of large rafts, directly absorbs nutrients in seawater and spreads by splitting into pieces and continuing to grow independently. According to the investigation, there are 8 species of Sargassum in this sea area, of which 2 species are absolutely dominant. Sargassum is the main species, and dozens of aquatic organisms with seaweed as the host form a unique Sargassum biological community. The salinity and temperature of seawater in the sargasso sea are relatively high, because it is far from the mainland and mostly located in the subtropical high pressure area, with less rain and strong evaporation; The high water temperature is due to the influence of warm current. The famous bay flows eastward through northern the sargasso sea, while the warm current from the northern equator flows westward through southern the sargasso sea. The movement of the above ocean currents makes the sargasso sea water slowly rotate clockwise.
Blue sea and blue sky-the clearest sea
The most obvious feature of the sargasso sea is its high transparency, which is recognized as the clearest sea in the world. The sargasso sea is far away from rivers and estuaries, and there are few plankton. The sea water is blue and the transparency is as deep as 66.5 meters, and some sea areas can reach 72 meters. Generally speaking, the seawater transparency in tropical waters is 50m, and that in the sargasso sea is 66m. No ocean in the world has such high transparency. The so-called seawater transparency refers to using a white circular plate with a diameter of 30 cm to vertically sink into the water out of direct sunlight until it is out of sight.
Sargassum, a floating plant in the sargasso sea.
The transparency of some sea areas in the sargasso sea is 72 meters. Whenever it is sunny, the photographic film can still be sensitive when it is placed at a depth above 1000 meters. This is beyond the reach of all other sea areas. Sargassum is a very peculiar sea area, and its geographical position (23 ~ 35 degrees north latitude and 40 ~ 75 degrees west longitude) is the center of Atlantic subtropical high. The clockwise ocean circulation along the edge of the high center forms its "coast", with the Gulf Warm Current in the west and north latitude, the Canary Cold Current in the east and the North Equatorial Warm Current in the south, enclosing an average area of 6.45 million square kilometers in the middle.
fish
There are many unique fishes living in the sargasso sea, such as flying fish, swordfish, marlin and Sargassum. Most of them take seaweed as the host, and they are good at camouflage and discoloration, and dress up as seaweed. The strangest thing is Sargassum fish. It is the same color as Sargassum, and its eyes can change color. When it meets an "enemy", it can swallow a lot of sea water and expand its body, making the "enemy" afraid to touch it easily.
Hainan aviation fog
1492, Columbus crossed the Atlantic Ocean. When passing through this sea area, the fleet found a large piece of vibrant green in the front view. They were surprised to think that the land was close at hand, but when the fleet approached, they found that "green" was originally Sargassum densely growing in the water. 1On the morning of August 3, 492, a fleet led by Columbus was surrounded by Sargasso. They sailed in the sargasso sea for three whole weeks before they were out of danger.
The sargasso sea is called "the graveyard of the sea".
From ancient times to the present, almost none of the ships that have strayed into this "green ocean" can return to Zhao intact. In the era of navigation, I don't know how many ships were entangled in Sargasso because they strayed into this strange sea area, and the people on board didn't survive because of the exhaustion of fresh water and food, so people called this sea area "the graveyard of the sea".
The sargasso sea has high salt content, warm seawater and abundant plankton.
In the eyes of navigators, the sargasso sea is a desert on the sea and the grave of ships. In this empty and dead sea area, almost no edible fish can be caught. Turtles and occasional whales seem to be the only life, except those unicellular algae. In popular stories, the sargasso sea is described as a huge trap. Passing ships will be caught by magical algae and trapped in the algae, leaving only the bones of sailors and the wreckage of the ship. As the most famous mysterious zone in this sea area, Bermuda Triangle has pushed the horror and magic of these legends to the extreme.
With the joint efforts of oceanographers and meteorologists, the reasons for the "strange tranquility" in the sargasso sea and the inexplicable grounding of ships have been found out. It turns out that this oval sea area of 3 million square kilometers is in the center surrounded by four major ocean currents. Under the interaction of the Gulf Stream in the west, the North Atlantic Warm Current in the north, the canary cold current in the east and the North Equatorial Warm Current in the south, the sargasso sea flows slowly in the clockwise direction, which is also the reason for the unusual "calm" here. It is for this reason that ancient ships relying on the help of wind and ocean currents stumbled in this sea area. Therefore, the problems of high salinity, warm seawater and abundant plankton in the sargasso sea have been solved. Although it has been proved that the algae in the the sargasso sea are not magical algae that block ships from advancing and devour sailors, the mysterious aura hanging over its head has not disappeared.
A sea without a coast
Most of the oceans in the world are the marginal parts of the ocean, adjacent to the mainland or other land. However, the sargasso sea in the middle of the North Atlantic is an "ocean in the ocean", and its west is separated from the North American continent by a vast sea area. The other three sides are vast oceans. Therefore, it is the only sea in the world without a coast, so there is no clear coastal demarcation line.
The sea surface of the sargasso sea is covered with green rootless seaweed-Sargassum, which seems to be a grassland scenery. Driven by the sea breeze and ocean currents, the floating Sargassum stretches far away like a huge olive carpet. Besides, it is also a windless area all year round. Before the invention of the steam engine, ships had to be in sail before the wind. At that time, if a ship rushed into this sea area, it would be trapped alive because there was no sailing power. So since ancient times, the sargasso sea has been regarded as a terrible "magic sea".
Spectacular sea grassland
After sailing in the Atlantic for many days, the Columbus expedition suddenly saw a large "grassland" in front of it on1September 6, 492. The land he was looking for was just around the corner, and Columbus happily ordered the fleet to speed up sailing. However, approaching "