The sea matters enormously in our lives, writes Dr Forkan Ali, a researcher and former principal. It holds a wealth of plant, animal and economic diversity and, above all, beauty. It gives us the oxygen we breathe, clouds and rain, and lessons in rising up against wrongs. It holds plain accounts of history and heritage, rainbow-like mysteries and strange wonders. That is why rhymesters, poets, novelists and researchers never stop writing about it, research never ends, and film-makers keep making dramas and films about it.

Human curiosity about the sea is endless. For all these reasons the sea draws us with its own character, like a magnet: the sea and people are like the opposite north and south poles that attract one another and bring everyone together.

The sea holds not only fish but seaweeds, oysters and other aquatic creatures. The term covers all aquatic and semi-aquatic plants and animals: freshwater and marine fish, hard-shelled creatures (which are not really fish) such as shrimp, crabs, oysters, snails, turtles and crocodiles, as well as various seaweeds and other plants.

Bangladesh has 260 species of freshwater fish, including estuarine species, and 475 species of marine fish. Notable among them are hilsa, several kinds of pomfret, flying fish, black and white croaker, ribbon fish, butterfly fish, puffer fish, golden snapper and several sharks, including saw, hammerhead and others. The sea also holds colourful and strangely shaped fish seen in aquariums and on television, such as swordtail, gambusia, cowfish, porcupine fish, dogfish, pipefish, gurnard, sea dragon, garfish, sea catfish, angelfish, parrot fish, scorpion fish and seahorse.

There are 36 species of shrimp, 336 of snails and oysters, 3 of lobster, 7 of turtle, 16 of crab, 10 of frog, 24 of snake, 3 of otter, 9 of dolphin, 3 of whale and 168 of algae.

Hilsa, the national fish, is the most abundant catch in our maritime area. Fishermen land about 3 lakh 40 thousand tonnes a year, providing a livelihood for some 25 lakh people. Of all the hilsa caught in the world today, 50-60 per cent comes from our waters in the Bay of Bengal. India catches 15-20 per cent and Myanmar (Burma) 20-25 per cent, with the remaining 5-10 per cent from other countries.

Our waters also hold great potential for bagda and golda shrimp, which contribute significantly to the economy. In 2022 a survey of our maritime area was carried out with two institutions from the United Kingdom and the Netherlands. It found large amounts of gas hydrate, along with 220 species of seaweed, 347 species of marine fish, 498 of oysters, 52 of shrimp, 5 of lobster, 6 of crab and 61 of seagrass.

Most of the plant life of the Pacific Ocean, and of the sea generally, is phytoplankton: single-celled algae numbering more than 1,300 species. There are also 400 species of algae and 29 of grasses, among them giant algae that grow up to 200 metres long. Plants include single-celled algae, diatoms, kelp, Cladophora, Ulva and Zostera. The Arctic Ocean has 200 species of algae along with Fucus, Ahnfeltia and blackjack. The Atlantic has phytoplankton, dark green algae, Phyllospadix, brown algae, Macrocystis, Chondrus and red algae.

The Indian Ocean has green, red and brown algae, known as seaweed, literally sea weeds, a kind of algae. These are photosynthesising, flowerless plants that usually grow on the sea floor and have no roots, branches or leaves. Of the three kinds, green seaweed is usually eaten. Seaweeds are also used in dairy, medicine, textiles, paper and gel products, and in cosmetics, toothpaste and shampoo. In the Bay of Bengal 220 species of seaweed have been identified, which will expand our future prospects. Macrocystis, Fucus, blue-green algae and Posidonia are also found here.

Plants that adorn the coast and the depths include Avicennia, Cymodocea nodosa, Halodule wrightii, Posidonia oceanica, Spartina alterniflora and Zostera marina. On beaches grow Alyssum loiseleurii, Armeria pungens, Asparagus macrorrhizus, Crithmum maritimum, Eryngium maritimum and Pinus halepensis.

In a Forbes report, geoscientist Trevornes said 2 crore tonnes of gold lie hidden at the bottom of the sea. Many have searched for it, but no one has found it, and it remains out of reach. Besides the gold on the sea floor there is "floating gold": a waxy substance released during digestion by the sperm whale, known locally as whale vomit and properly as ambergris. Lumps of about 9-30 kg are sometimes expelled and float on the sea. Many fishermen have become millionaires by finding it, but several countries have declared it state property and buying or selling it is a punishable offence.

A whale is not a fish but an aquatic mammal, like humans. Fish breathe with gills, while whales breathe with lungs, as we do. Besides gold, the sea floor is full of valuable minerals, including vast amounts of oil and gas, and the Bay of Bengal is no exception. Newspapers have reported uranium and thorium, and sand more valuable than gold at 13 sites, containing garnet, sillimanite, zircon, ilmenite, rutile and magnetite. In shallow areas lies clay, in quantities greater than the Himalayas, which is used to make cement. Valuable oil and gas have also been found.

There is fire beneath the sea, too: volcanoes. Water and fire are opposites, like the snake and the mongoose, yet molten lava bursts up through the ocean. According to scientists, there are between 100 and 1,000 active undersea volcanoes in the world, spewing not only lava but a great deal of ash. Three-quarters of the world's volcanic activity takes place on the sea floor.

According to Bangladesh government data, 33 major cyclones struck from the sea between 1960 and 2017. The most devastating were the cyclones of 1970 and 1991, followed by Cyclone Sidr. They caused enormous damage and lakhs of people lost their lives. Other notable cyclones include Aila, the Backergunge cyclone, Nargis, Mahasen, Komen, Roanu, Mora and Mocha. The writer says these arise from environmental degradation, for which humans are most to blame, and that we must become aware of marine pollution and its causes.

Human activity is constantly polluting sea water, damaging marine biodiversity and other economic resources, and harming us in turn. The main causes are plastic waste, industrial waste and waste from ships. Three parts of our planet are water and one part land. The oceans meet the protein needs of about 100 crore people, and by 2030 about 4 crore people worldwide will be connected to the sea in some way. Our recreation, human development and economic well-being depend on this mysterious sea, so for our own sake it must be cared for.

Source: Jagonews24. First published in Bengali on The Agro News.