Posts tagged with marine biology...
Marine Snow-Until about 130 years ago, scholars believed that no life could exist in the deep ocean. The abyss was simply too dark and cold to sustain life. The discovery of many animals living in the abyssal environment stunned the late 19th century scientific community. Major questions immediately emerged: How do deep sea animals obtain food so far from the ocean’s surface where plants, the base of the ecosystem, grow? Soon after World War II, scientists at Hokkaido University built an early submersible, named Kuroshio, to dive in the ocean north of Japan. Wherever they beamed a search light, they saw “snowflakes” dancing from the disturbance caused by the submersible. K. Kato and N. Suzuki named this phenomenon “marine snow.”
Marine snow is a continous shower of organic detritus that falls from the sunlit upper layers into the deep ocean. It consists of dead or dying animals and plants, fecal matter, and inorganic dust, clumped together in loose flocs. In the deep ocean it is consumed by a variety of animals or decomposes. Many marine snow “flakes” are sticky and fibrous like a crumbled spider net, and particles easily adhere to them, forming agregates. An aggregate begins to sink when it attracts fecal pellets, foraminifera tests, airborne dust, and other heavier particles. As it descends, more suspended particles are added, making the aggregate even heavier and thus faster moving.
Marine snow is a significant energy source and a mechanism for transporting carbon into the deep ocean (known as the biological carbon pump), allowing for life in the deep.
SHARKS ARE IMPORTANT, GUYS!
(Photo found here)
The Indian glassy fish (Parambassis ranga), is a species of freshwater fish in the Asiatic glassfish family (Ambassidae) of order Perciformes (see this post). It is native to an area of south Asia from Pakistan to Malaysia. The Indian glassy fish has a striking transparent body revealing its bones and internal organs; the male develops a dark edge to the dorsal fin. The fish grows to a maximum overall length of 80 millimeters (3.1 in). It occurs in standing water, especially in impoundments, and it breeds prolifically during the rainy season. The Indian glassy fish is not important as a food fish for humans, but is very common in the aquarium trade. Formerly classified as Chanda ranga, the species is also known as the Indian glassfish, Indian glass perch, and Siamese glassfish. Indian glassy fish sold to hobbyists have often been “painted”, which involves injecting colored dye into the fish’s transparent tissue to make them more attractive to hobbyists. These colored fish are often called “disco fish”(see this post).
(Photo found here)
The blue whale (Balaenoptera musculus) is a marine mammal belonging to the suborder of baleen whales (called Mysticeti, see this post). Blue whales are the largest animals ever known to have lived on Earth. These magnificent marine mammals rule the oceans at up to 100 feet (30 meters) long and upwards of 200 tons (181 metric tons). Their tongues alone can weigh as much as an elephant. Their hearts, as much as an automobile.
Blue whales reach these mind-boggling dimensions on a diet composed nearly exclusively of tiny shrimplike animals called krill (see this post). During certain times of the year, a single adult blue whale consumes about 4 tons (3.6 metric tons) of krill a day. Blue whales are baleen whales, which means they have fringed plates. Blue whales look true blue underwater, but on the surface their coloring is more a mottled blue-gray. Their underbellies take on a yellowish hue from the millions of microorganisms that take up residence in their skin.
Blue whales live in all the world’s oceans occasionally swimming in small groups but usually alone or in pairs. They often spend summers feeding in polar waters and undertake lengthy migrations towards the Equator as winter arrives. Blue whales are among the loudest animals on the planet. They emit a series of pulses, groans, and moans, and it’s thought that, in good conditions, blue whales can hear each other up to 1,000 miles (1,600 kilometers) away. Scientists think they use these vocalizations not only to communicate, but, along with their excellent hearing, to sonar-navigate the lightless ocean depths.
Blue whale calves enter the world already ranking among the planet’s largest creatures. After about a year inside its mother’s womb, a baby blue whale emerges weighing up to 3 tons (2.7 metric tons) and stretching to 25 feet (8 meters). It gorges on nothing but mother’s milk and gains about 200 pounds (91 kilograms) every day for its first year. Blue whales are among Earth’s longest-lived animals. Scientists have discovered that by counting the layers of a deceased whale’s waxlike earplugs, they can get a close estimate of the animal’s age. The oldest blue whale found using this method was determined to be around 110 years old. Average lifespan is estimated at around 80 to 90 years.
Between 10,000 and 25,000 blue whales are believed to still swim the world’s oceans. Aggressive hunting in the 1900s by whalers seeking whale oil drove them to the brink of extinction. Blue whales have few predators but are known to fall victim to attacks by sharks and killer whales, and many are injured or die each year from impacts with large ships. Blue whales are currently classified as endangered on the World Conservation Union (IUCN) Red List.
(Source of photo here)
Deeper than even the light of the Sun can reach there is a cauldron bubbling up a life giving essence. Hydrothermal vents are among the most unique structures on the ocean floor, providing for life in a world devoid of it. A hydrothermal vent is a fissure in a planet’s surface from which geothermally heated water issues. Hydrothermal vents are commonly found near volcanically active places, areas where tectonic plates are moving apart, ocean basins, and hotspots. Hydrothermal vents exist because the earth is both geologically active and has large amounts of water on its surface and within its crust. Common land types include hot springs, fumaroles and geysers.
Under the sea, hydrothermal vents may form features called black smokers. Relative to the majority of the deep sea, the areas around submarine hydrothermal vents are biologically more productive, often hosting complex communities fueled by the chemicals dissolved in the vent fluids. Chemosynthetic archaea form the base of the food chain, supporting diverse organisms, including giant tube worms, clams, limpets and shrimp. The discovery of hydrothermal vents shook the world of science because they proved that Earth could sustain life all by itself by producing energy from chemicals in a process called chemosynthesis rather than through the process of photosynthesis, which requires the sun. Active hydrothermal vents are believed to exist on Jupiter’s moon Europa, and ancient hydrothermal vents have been speculated to exist on Mars.
The accepted origin of hydrothermal vents is from sub-surface water being super heated, coinciding with their predominance around volcanically active regions, by magma causing fissures in the ocean floor. Expelled from these fissures is a collection of various minerals, with the most prominant being sulfide. Because of their location at incredibly deep depths, with the average depth of hydrothermal vents existing at 7,000 feet, the surrounding water is incredibly cold while the expelled solution from the vent is absurdly hot, reaching temperatures close to 850 degrees Fahrenheit. This results in a precipation effect that allows the vents to slowly build into massive columns.
(Photo found here)
The leopard seal (Hydrurga leptonyx) is named for its black-spotted coat. This seal is sometimes called the sea leopard, and the resemblance is more than skin deep. Like their feline namesakes, leopard seals are fierce predators. They are the most formidable hunters of all the seals and the only ones that feed on warm-blooded prey, such as other seals. Leopard seals use their powerful jaws and long teeth to kill smaller seals, fish, and squid. These effective predators live in frigid Antarctic and sub-Antarctic waters, where they also eat penguins. They often wait underwater near an ice shelf and snare the birds just as they enter the water after jumping off the ice. They may also come up beneath seabirds resting on the water surface and snatch them in their jaws. Shellfish are a far less dramatic prey but still an important part of the leopard seal’s diet. They have long bodies (10 to 11.5 feet/3 to 3.5 meters) and elongated heads. Like most other seals, leopard seals are insulated from frigid waters by a thick layer of fat known as blubber. There has been one documented human fatality by a leopard seal.