Do Now

• Think about what you had for breakfast this morning.

• Where did it come from? • How does that thing(s) grow and

survive?

Hydrothermal Vents

EQ: How do hydrothermal vents work? How does life survive there?

When were they found?

• Hydrothermal Vents were first discovered in 1977 off the Galapagos Islands

• There is a spreading center there between the Cocos Plate and the Nazca Plate

• The submersible ALVIN was used to find the vents.

Where are they found? • Hydrothermal Vents are found

mostly near mid-ocean ridges, although there are new types being discovered at other plate boundaries and hotspots

How do they work? • 1. Cold sea water seeps into the

crust through cracks and fissures • 2. The water is heated up to

400*C from the magma, and reacts with the surrounding rock. Oxygen, magnesium, and potassium are removed. The water becomes acidic, and dissolves metals like copper, zinc, and iron. Sulfur also dissolves to make hydrogen sulfide.

How do they work? • 3. The hot liquid mixture is less

dense, so it rises up. As it does, it begins to cool and some of the metals and minerals get deposited to build up the chimney.

• 4. The rest of the liquid exits the chimney. The dark color seen is from the rest of the metals and minerals falling out of solution, and onto the sea floor surrounding the vent.

How are they classified? • Vents are classified by their water

temperature. • Black smokers are the hottest vents,

with temperatures above 350°C (662°F)

• White smokers are cooler, with temperatures from 30–350°C (86–662°F). The vent fluids mix with sea water below the surface, cooling them down and depositing some darker minerals.

• Warm water vents have temperatures below 30°C (86°F). They are more like a warm spring under the ocean.

What lives there? • The base of the food chain is

bacteria.• There are animals that have the

bacteria live inside them to provide them with food. These include tube worms, clams, and mussels

• There are scavengers, including shrimp, crabs, and anemones that feed on the bacteria and other zooplankton that live at the vent

• Lastly, there are predators including octopi, fish, and squid that feed on other vent creatures.

Wait a minute….no plants?

• These vents are found below 1000m.

• Photosynthesis can only happen until 100m underwater

• The bacteria here use the hydrogen sulfide in the water and turn it into energy to survive.

• Making energy through chemical reactions instead of the sun is called chemosynthesis.

Chemosynthesis

• Bacteria take in hydrogen sulfide along with oxygen and turn it into carbon dioxide and sugars.

• For the bacteria, the hydrogen sulfide is their food. Sugars are their waste product…..but lots of other things view that as food!

• Tube worms, clams, and mussels allow the bacteria to live in their bodies, eating the sugars the bacteria make. They do not make their own food, and are dependent on the bacteria.

Up the food chain

• There are bacteria living along the sea floor around the vent, forming a bacterial mat.

• The shrimp, crabs, and other small microscopic animals (zooplankton) are scavengers, meaning they eat other pieces of organic matter.

• They will eat the bacterial mat, and pick at the clams, tube worms, and mussels.

• Larger predators will have to eat other vent animals, like the shrimp and crabs.

• Spreading out on the sea floor along the bacterial mat, many other invertebrates, like snails, can be found.

Life in the fast lane

• A specific hydrothermal vent may only be active for a few years. The magma chamber near it could shift, there could be a large eruption engulfing the vent, or the vent could become clogged and no longer work.

• Vent organisms need to mature and grow quickly compared to their open sea counterparts.

• They also reproduce frequently, to spread their offspring to different vent sites.

Life in the fast lane

• Worms, shrimp, crabs, clams, and mussels all have mobile larval stages, so they can move to other vents.

• Larger animals like fish and octopi can move from vent to vent on their own.

• The bacteria can drift through currents, and are often found far from a vent site.

The Big Picture

• Life at hydrothermal vents are up to 10,000 times more dense than the open sea surrounding it.

• Other types of sites, like cold seeps, have been discovered as well. In cold seeps, methane and hydrogen sulfide seep out from the ocean floor. Similar types of animals are found there, again using chemosynthesis to survive.

• Scientists are studying the life at these sites, wondering if they influenced how life could have begun on earth, and the importance of being able to survive without photosynthesis.

Closure

• In small groups, use the creature cards to recreate a hydrothermal vent ecosystem.

• Fill in the corresponding chart on the end of your notes.