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Strange-but-true findings about vent environments

Scientists have learned that some processes occur very quickly at vents. For example, giant tube worms can grow as fast as 2 meters a year, and "smokers" or chimneys can rise up to 7 feet or more in less than a year. In a couple of years a barren vent can become a bustling community composed of many unusual animals.

Other processes seem to take place very slowly at vents. An example is decomposition. When an accident caused scientists to leave a bologna sandwich behind, they found it in nearly the same condition when they returned to the site a year later. Similarly, dead tube worms they had observed on one expedition were mostly unchanged when the scientists returned the following year.

How long do vents live?

A vent habitat is a very unpredictable place in which to live. Some vents are active for several decades, others may live longer. Some vents may live only a few years or less.

Why do vents die?

Volcanic activity, earthquakes, and other events can extinguish a vent at any time. A chimney may collapse and block the flow of hydrothermal fluid, precipitates may build up, like cholesterol in an artery, choking the vent, or the supply of heat and fluid to the vent may simply become exhausted.

Beginging of Life

Some Japanese researchers have claimed to prove that life could have arisen in a submarine hydrothermal vent. However, the most complex molecule their ‘simulation’ produced was hexaglycine, in the microscopic yield of 0.001%.  Compared to the complexity of even the simplest living cell, hexaglycine is extremely simple.  High temperatures would degrade any complex molecules over the alleged geological time.

Tube Worms only found along Pacific ridges?

Only a small amount of the Earth's oceanic ridges has been surveyed so far. But with what little we do know it has been found that tube worms are only found in the Pacific while shrimps are found at the bottom of both oceans.

Why? The tube worm larva are unable to feed while traveling to a new vent system during breading. This means that they can only travel short distances while the carnivorous shrimp larva are able to survive much longer.

Pacific ridges are located on fast moving plates which produce vent systems that are closer together, while on the slower moving Atlantic plates, vent systems are spread further apart. This means that tube worm larva are unable to make the longer journey between vents in the Atlantic, but are fine in the Pacific.

If mining is allowed on vent systems within the Pacific, it could remove a number of vent systems, therefore increasing the distance between vents that have been left behind.

Even if the mining companies leave some vent systems untouched, mining could still result in the loss of some species if their offspring are unable to make the move to new vent systems during reproduction.



Life on Hydrothermal Vents

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Most living things on earth depend on sunlight as the ultimate source of energy. Green plants use sunlight to make food by the process of photosynthesis. In the darkness of the ocean depths there is no sunlight for photosynthesis. So how do living things survive in such an environment? The answer is found in bacteria that can use another source of energy to make food.

Water coming out of a vent is rich not only in dissolved minerals but also in chemosynthetic bacteria. These bacteria are capable of utilizing sulfur compounds to produce organic material through the process of chemosynthesis. The bacteria are autotrophs that oxidize hydrogen sulfide in vent water to obtain energy, which is used to produce organic material.

Chemosynthetic bacteria are the primary producers and form the base of vent food webs. All vent animals ultimately depend on the bacteria for food.

When a vent forms, new lava on the ocean floor around the vent becomes covered with a thick mat of bacteria. Soon tiny animals such as amphipods and copepods come to feed on the bacteria. Gradually, larger animals, including grazers, scavengers and predators join in colonizing the vent.

Scientists studying a field of vents since their formation in 1991 have observed a pattern of colonization. The first organisms to populate the vents are bacteria, then other microorganisms, including amphipods and copepods appear.

These are followed by limpets (snails), shrimp, crabs, tube worms, fish, and octopi. Sometime later acorn worms, dandelion-like animals, and other species of shrimp and tube worms add to the expanding community. In their most advanced stages vents are home to mussels, a variety of worms, anemones, and a large population of crabs, as well as many of the earlier colonists.  

Some vent animals, like limpets, clams, and mussels feed directly on bacteria. Other animals, such as octopi, prey on those that eat bacteria. Vent crabs act as both predator and scavenger. Some of the most successful vent animals, tube worms and giant clams, form symbiotic relationships with chemosynthetic bacteria. The bacteria live within the animals' tissues and provide a built-in food supply.

Hydrothermal vent tube worm
Giant Tube Worm
Over 300 new species of animals have been discovered at vents. Many are found nowhere else on earth, and could not exist outside the conditions at vents.

Hydrothermal tube worms

Tube Worms
Vestimentiferan Tube Worms are one of the most abundant and best-understood of the animals that live in deep-sea hydrothermal vent communities. Baby tube worms are called larvae, and they can swim. Adults, on the other hand, are sessile which means that they stay in one place and are attached to the ground beneath them. Adult tube worms have no mouth, gut, or anus, and thus they do not eat, digest, and eliminate waste the way that we do. Instead the tube worms rely on bacteria living within them (symbionts) to provide them with their nutrition. The distinctive bright red plume or tip of the tube worm is the only part of the worm's anatomy that is exposed to the environment, and it can be fully withdrawn into the protective tube when the animal is disturbed. Tube worms use this plume to take up sulfide and oxygen from vent waters. The sulfide and oxygen are transported, along with other nutrients, by the blood of the tube worm to the bacteria living within the worm's tissue. These bacteria combine these nutrients and chemicals into food for themselves and their host tube worm.

Two species of tube worm inhabit hydrothermal vents. The smaller of the two, Tevnia jerichonana, which grow at a rate of 30 centimeters per year, are among the first animals to colonize and dominate the ventecosystem. Riftia pachyptila, which grow much faster (85 centimeters per year) and reach over 2 meters in length, eventually replace Tevnia as the dominant species.

Hydrothermal vent clams

Vescomyid Clams are deep-sea hydrothermal vent cousins to the clams that we're all familiar with. Although these chalky white clams retain some ability to filter-feed, like the tube worms these clams rely on their bacterial symbionts that live within their gills for the major source of their nutrition. The symbionts receive nutrients and oxygen, which flow into the clam through the uppermost end of the shell, and sulfide, which is incorporated through the bright red foot that can be extended several times the body length of the clam down into the sulfide-rich vent water below their shells.

Hydrothermal vent mussels

Bathymodiolid Mussels are deep-sea hydrothermal vent cousins to the mussels that we're all familiar with. Although better filter feeders than the deep-sea clams, like the tube worms these mussels also rely on bacterial symbionts that live in the cells which cover the surfaces of their gill filaments for some of their nutrition. Unlike the clams and the tube worms, these mussels harbor more than one type of bacterial symbiont. The combination of an enhanced ability to filter-feed and the presence of multiple types of bacterial symbionts enables these mussels to survive farther from the direct sources of vent water relative to the clams and the tube worms.

Hydrothermal vent shrimps

There are 15 species of shrimp that live around vent sites throughout the world. Roughly half live in the Atlantic and half live in the Pacific. In the Pacific Ocean, each vent site supports only one species of shrimp. They typically live around clumps of tube worms and mussels. 

In the Atlantic Ocean, shrimp often gather in huge swarms along the sides of active black smokers. These swarms may contain as many as 30 thousand animals per square meter. The shrimp eat microbes that grow on the chimney and may even eat the microbes that grow on their bodies. Some also eat mussels. Crabs, anemones, and zoarcid fish eat shrimp.

Hydrothemal vent crab

There are several species of crabs that live around hydrothermal vents. One type is the Galatheid crab, or squat lobster. These white crabs live throughout the ocean, but their numbers increase around hydrothermal vents where food is plentiful. These crabs are scavengers. They hang out in mussel beds where they eat bacteria and dead animals. 

Brachyuran crabs live around vent sites in the Pacific Ocean. These round white crabs are fierce predators. They eat bacteria, shrimp, mussels, clams, tubeworms, and even each other.

Hydrothermal vent dandelion Dandelions
These fuzzy-looking balls are made up of a colony of numerous individual animals that hold onto each other. The animals in these colonies are related to the Portuguese-Man-O- War and other jellyfish. They use long whisker-like tentacles to anchor themselves on rocks and to move around. 

The dandelions are scavengers. They are some of the last animals to colonize vent sites. If there are a lot of dandelions around a vent site, it usually means that the vents are no longer active and most of the other organisms in the area are dying.

Hydrothermal vent zoarcid fish

Zoarcid Fish

These two-foot long white fish are top predators around vents. They eat everything from tubeworms to shrimp. Despite their huge appetites, these fish are slow and lethargic. They spend a lot of time floating around clumps of tube worms and mussels.

Hydrothermal vent octopi

There are several species of octopi that only live around hydrothermal vents. Some species have only been seen a few times. They are typically one meter long, and their heads are about the size of an orange. 

Octopi are top predators. They live among or even under clumps of mussels. They eat crabs, clams, and mussels.

Hydrothermal vent pompeii worm

Pompeii Worm

The pompeii worm is a fuzzy gray animal with scarlet gills on its head. The gray "fur" on pompeii worms are actually bacteria. Pompeii worms are theworld's most heat tolerant animal, living among hydrothermal vents, and can withstand up to 176 degrees Fahrenheit. Pompeii worms makes a sort of papery colony attached to the chimneys of hydrothermal vents. Vent chimneys are very porous, so heat can easily escape from the sides into the papery colonies of pompeii worms. The back part of the worm's body sits in water as high as 176 degrees Fahrenheit while its head, which rests outside the colonies, is in water about 72 degrees Fahrenheit.


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