Amazing secrets in the ocean

Dolphins with penetrating vision, brain-eating or catfish-eating ink, with up to 100,000 spikes are interesting memorabilia of the ocean world discovered by scientists.

Giant squid (Mesonychoteuthis hamiltoni) was previously considered a marine creature that only appeared in legend. In 2007, a 10-meter long and 450-kilogram squid was caught by fishermen in the Ross Sea near Antarctica. After being taken to research in New Zealand, scientists found the giant squid with digestive system running through the brain center. The brain of a giant squid is shaped like a ring. When swallowing, the throat pushes food through the brain, then the brain directly absorbs nutrients before food is transferred to the stomach.

Piranha is a carnivorous fish with sharp teeth and swimming behavior into a hundred-large herd, almost no rivals in the Amazon River, South America. To be able to coexist peacefully with this ferocious fish, arapaima fish must be able to give themselves a protective layer like a sturdy armor in front of the teeth of aggressive fish. Arapaima fish skin consists of two layers, a hard outer shell made of hard minerals and a soft inner layer, with an elastic collagen structure. When attacked, the multi-step inner structure bends and glides around each other, avoiding the fierce fights of piranhas.

SAR11 is a bacterium that is present throughout the oceans of the earth. The enemy of SAR11 is the pelagiphage virus, which normally lives in any place where SAR11 bacteria appear and massively kills these bacterial cells. Before the attack of pelagiphage virus, SAR11 bacteria continuously evolved to maintain the race. Without giving up, the pelagiphage subfamily always evolved to chase new generations of SAR11. The constant battle between these two fairly common bacteria is only observed through a microscope.

Catfish has about 100,000 taste buds all over the body. The larger the fish, the more prickly the spines are, the largest fish may have more than 175,000 taste buds. Catfish use taste buds as a tool of prey by the pond bottom habitats filled with mud and soil, making their vision limited. With taste buds distributed throughout the body, catfish can sense prey from many meters away. Depending on where the taste signal is on the body is the strongest, they will rotate in that direction to head towards the prey. According to the researchers, this fish can detect prey even without eyes.

Dolphins use ultrasonic waves in almost every activity such as underwater orientation, hunting, and communicating with other dolphins. Ultrasonic waves of dolphins are created by pushing air through a network of cells located near their two air vents. Below the dolphin jaw is a fat bag that receives the reflected waves back and sends signals to the brain, producing images of the ocean in front of them.

Sound waves of dolphins with a frequency of 40-130kHz are able to pass through soft objects like the skin of other fish and reflect it when meeting hard bone and cartilage. Observing the behavior of dolphins, the researchers found that dolphins can identify when a shark has been fed, a female dolphin is pregnant and can even find bait hidden in the sand at one meter deep.

Swellshark sharks are small, no more than a meter long, living on the sea floor, eating only shrimp, crabs and squid, not chasing other fish like most sharks.

Swellshark sharks are also often attacked by enemies. However, in order to escape from the enemy, they often camouflage by using skin color mixed with the color of the seabed, or suck water into the pockets around the abdomen and bulge to twice the normal size, after it bends and closes its tail, clinging to the surrounding rocks, making it harder for larger fish to attack.

The Pompeii worm (Alvinella pompejana) is the hottest worm on the planet and is also a very difficult worm to study. Pompeii can be up to 13cm long and usually live in black chimneys where there are heat vents in the sea floor. The worm thrives in places with extreme temperatures and pressures and will die when taken ashore. Scientists discovered a class of bacteria that live around the worm's body as a barrier, which absorbs some of the heat from seawater, so that the worm can withstand the high temperature marine environment. In return, the Pompeii worm feeds on bacteria with their viscous substance.

Anguilla eels are often found in lakes, rivers and streams in Northern Europe and England. However, eels are not always underwater, they can go ashore and crawl on the ground for a short time. Eels go ashore to find food like insects, earthworms and to migrate. This fish lives about 20 years in a fixed lake, but in the early stages of life and at the end of its life, it takes place about 6,500km away, in the Sargasso Sea, off the north coast of the Atlantic. To move from the lakes in Europe to the sea, eels swim along rivers and streams. When meeting places where water is blocked by a dam, they go ashore and cross fields or forests, until they reach the next water flow.

The Sargasso Sea , to the north of the Atlantic Ocean, is the most unique sea in the world with an almost completely self-sufficient ecosystem. At night, the Sargasso Sea is the site of the migration of 5,000 marine species, including a variety of marine life from the deep ocean floor to search for food, then return to the ocean floor before dawn .