remiconnesson/oceanservice-noaa-facts huggingface dataset:
# What is bioluminescence?

## Bioluminescence is the production and emission of light by a living organism.

![http://oceanexplorer.noaa.gov/facts/bioluminescence.html  Image courtesy of Islands in the Sea 2002, NOAA/OER.](/facts/biolum.jpg "Many deep-sea organisms are able to emit 'living light' through a chemical reaction, bringing light to the otherwise total darkness of the deep ocean. Image courtesy of Islands in the Sea 2002, NOAA/OER.")

Bioluminescent creatures are found throughout marine habitats, from the ocean surface to the deep seafloor.

The light emitted by a bioluminescent organism is produced by energy released from chemical reactions occurring inside (or ejected by) the organism.

If you’ve ever seen a firefly, you have encountered a bioluminescent organism. In the ocean, bioluminescence is not as rare as you might think. In fact, most types of animals, from bacteria to sharks, include some bioluminescent members.

While the functions of bioluminescence are not known for all animals, typically bioluminescence is used to warn or evade predators), to lure or detect prey, and for communication between members of the same species.

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While some animals in the ocean emit light, some organisms absorb light, transform it, and eject it as a different color. This phenomenon, called [bioflourescence](http://www.nsf.gov/discoveries/disc_summ.jsp?cntn_id=130105), may be used in communication and mating.

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**Last updated:** 06/16/24  
**Author:** NOAA  
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- While some animals in the ocean emit light, some organisms absorb light, transform it, and eject it as a different color. This phenomenon, called [bioflourescence](http://www.nsf.gov/discoveries/disc_summ.jsp?cntn_id=130105), may be used in communication and mating.
# Why does the ocean get colder at depth?

## Cold, salty water sinks to the bottom of the ocean.

![global ocean conveyor belt](/facts/coldocean.jpg "global ocean conveyor belt")

The [great ocean conveyor](/facts/conveyor.html) moves water around the globe. Cold, salty water is dense and sinks to the bottom of the ocean while warm water is less dense and remains on the surface.

Cold water has a higher density than warm water. Water gets colder with depth because cold, salty ocean water sinks to the bottom of the ocean basins below the less dense warmer water near the surface. The sinking and transport of cold, salty water at depth combined with the wind-driven flow of warm water at the surface creates a complex pattern of ocean circulation called the 'global conveyor belt.'

In contrast, the Earth gets hotter and hotter at depth primarily because the energy of radioactive decay is [leaking outwards from the core of the planet](http://pubs.usgs.gov/gip/dynamic/unanswered.html). While this geothermal energy is transferred to ocean water along the seafloor, the effect is so small that it's immeasurable by direct means.

Why? The actual amount of heat generated per square meter of Earth is quite small, especially compared to the amount of heat necessary to warm the ocean. Geothermal energy emanating from the Earth averages only about one tenth of a watt per square meter. At that rate of heat flow (without taking ocean currents into account), it would take well over a year just to heat the bottom meter of the ocean by one degree Centigrade.

However, the ocean is not standing still. Complex deep ocean currents driven by density variations in temperature and salinity are constantly replacing the bottom layer of ocean water with colder water.

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Winds drive currents that are at or near the ocean's surface. Near coastal areas winds tend to drive currents on a localized scale and can result in phenomena like coastal [upwelling](/facts/upwelling.html).

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**Last updated:** 06/16/24  
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- Winds drive currents that are at or near the ocean's surface. Near coastal areas winds tend to drive currents on a localized scale and can result in phenomena like coastal [upwelling](https://oceanservice.noaa.gov/facts/upwelling.html).
# What is an eddy?

![sattelite view of ocean eddies](/facts/eddy.jpg)

_Can you spot the eddies? This [NASA](https://www.nasa.gov/image-feature/taking-to-the-air-and-sea-to-study-ocean-eddies) image, eddies and small currents are responsible for the swirling pattern of these phytoplankton blooms (shown in green and light blue) in the South Atlantic Ocean on Jan. 5, 2021._

The ocean is a huge body of water that is constantly in motion. General patterns of ocean flow are called [currents](/facts/current.html). Sometimes theses currents can pinch off sections and create circular currents of water called an eddy.

You may have seen an eddy if you've ever gone canoeing and you see a small whirlpool of water while you paddle through the water. The swirling motion of eddies in the ocean cause nutrients that are normally found in colder, deeper waters to come to the surface.

Significant eddies are assigned names similar to hurricanes. In the U.S., an oceanographic company called Horizon Marine assigns names to each eddy as they occur. The names follow chronologically along with the alphabet and are decided upon by staff at Horizon Marine. The staff try to think of creative ways to assign names.

For example, an eddy that formed in the Gulf of America (formerly Gulf of Mexico) in June 2010 is named Eddy _Franklin_ after Ben Franklin, as he was known to have done research on the [Gulf Stream](/facts/gulfstreamspeed.html).
# What are the three main types of coral reefs?

## The three main types of coral reefs are fringing, barrier, and atoll.

![coral reef](/facts/most-coral.jpg "Colorful reef fish - Pennantfish, Pyramid and Milletseed butterflyfish")

Schools of colorful pennantfish, pyramid, and milletseed butterflyfish live on an atoll reef in the Northwestern Hawaiian Islands.

The most common type of reef is the fringing reef. This type of reef grows seaward directly from the shore. They form borders along the shoreline and surrounding islands.

When a fringing reef continues to grow upward from a volcanic island that has sunk entirely below sea level, an atoll is formed. Atolls are usually circular or oval in shape, with an open lagoon in the center.

Barrier reefs are similar to fringing reefs in that they also border a shoreline; however, instead of growing directly out from the shore, they are separated from land by an expanse of water. This creates a lagoon of open, often deep water between the reef and the shore.

Coral reefs are important because they bring in billions of dollars to our economy through tourism, protect coastal homes from storms, support promising medical treatments, and provide a home for millions of aquatic species.

NOAA’s Coral Reef Conservation Program works to protect coral reefs through research, education, and preservation programs. Many reefs, such as the Virgin Islands Coral Reef National Monument, are housed in NOAA’s system of [marine protected areas](http://marineprotectedareas.noaa.gov/).
# Where is the largest protected area in the National Marine Sanctuary system?

## The largest marine sanctuary is located in the middle of the Pacific Ocean

![Papahanaumokuakea Marine National Monument](/facts/nms-largest.jpg " Papahānaumokuākea Marine National Monument")

Papahānaumokuākea Marine National Monument— larger than all of America’s national parks **combined**!

The Papahānaumokuākea Marine National Monument is not only the largest conservation area in the U.S., it's one of the largest marine conservation areas in the world. It's larger than all of America’s national parks combined! This vast region preserves many of Hawaii’s Northwestern Islands and is made up of hundreds of square miles of reefs, atolls, shallow waters, and deep seas.

The monument contains a wide variety of critically important habitats that harbor over 7,000 marine species, several of which are only found in this region. It is also home to many rare and endangered species such as the green sea turtle and the Hawaiian monk seal.

The Papahānaumokuākea Marine National Monument is one of a growing number of marine protected areas that form NOAA’s National Marine Sanctuary system. The goal of this system is to conserve, protect, and enhance the biodiversity, ecological integrity, and cultural legacy of these areas.
# What is the difference between a hurricane and a typhoon?

## The only difference between a hurricane and a typhoon is the location where the storm occurs.

![A close-up satellite image of Hurricane Isabel taken on Sept. 15, 2003. ](/facts/cyclone1.jpg "A close-up satellite image of Hurricane Isabel taken on Sept. 15, 2003. ")

A close-up satellite image of Hurricane Isabel taken on Sept. 15, 2003. The National Ocean Service helps coastal communities prepare for and recover from major coastal storms such as hurricanes.

Hurricanes and typhoons are the same weather phenomenon: [tropical cyclones](https://www.nhc.noaa.gov/climo/).  A tropical cyclone is a generic term used by meteorologists to describe a rotating, organized system of clouds and thunderstorms that originates over tropical or subtropical waters and has closed, low-level circulation. 

The weakest tropical cyclones are called _tropical depressions_. If a depression intensifies such that its maximum sustained winds reach 39 miles per hour, the tropical cyclone becomes a _tropical storm._  Once a tropical cyclone reaches maximum sustained winds of 74 miles per hour or higher, it is then classified as a hurricane, typhoon, or tropical cyclone, depending upon where the storm originates in the world.  In the North Atlantic, central North Pacific, and eastern North Pacific, the term _hurricane_ is used. The same type of disturbance in the Northwest Pacific is called a _typhoon_. Meanwhile, in the South Pacific and Indian Ocean, the generic term _tropical cyclone_ is used, regardless of the strength of the wind associated with the weather system.

The ingredients for tropical cyclones include a pre-existing weather disturbance, warm tropical oceans, moisture, and relatively light winds. If the right conditions persist long enough, they can combine to produce the violent winds, large waves, torrential rains, and floods we associate with this phenomenon.  At times, when a weather system does not meet all of these conditions, but is forecast to bring tropical storm or hurricane force winds to land in the next day or two, it is called a _potential tropical cyclone_ in the Atlantic basin and the central and eastern North Pacific basins.

In the Atlantic, hurricane season officially runs from June 1 to November 30. Ninety-seven percent of tropical cyclone activity occurs during this time period. However, there is nothing magical about these dates. Hurricanes can and do occur outside of this six month period.

[Learn more](http://www.nhc.noaa.gov/climo/)

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The [main parts of a tropical cyclone](https://www.weather.gov/jetstream/tc_structure) are the rainbands, the eye, and the eyewall. Air spirals in toward the center in a counter-clockwise pattern in the northern hemisphere (clockwise in the southern hemisphere), and out the top in the opposite direction. In the very center of the storm, air sinks, forming an "eye" that is mostly cloud-free.

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**Last updated:** 06/16/24  
**Author:** NOAA  
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# What is the significance of the NOAA logo?

![NOAA logo](noaa-emblem-rgb-2022.png)

_The above design was chosen as NOAA's emblem in 1971. It remains the official emblem of the agency to this day._

In 1970, NOAA was officially recognized and all of its components were united under a common name and mission. One year later, NOAA's first administrator, Dr. Robert White, gave NOAA employees the choice of three designs to be the official emblem for the new agency.

The chosen design was made the official NOAA emblem later that year and remains the official emblem of the agency to this day.

About the winning design, Dr. White remarked that: "A white, gull-like form links the atmosphere to the sea or Earth. The Earth and atmosphere and the interrelationships between the two are, of course, major concerns of NOAA. The line defining the top of the gull's wings also resemble the trough of a foaming ocean wave against the blue sky. A creature of sea, land, and air, the gull adds an ecological touch to the Earth-sky motif."
# What is bathymetry?

## Bathymetry is the study of the **"beds" or "floors" of water bodies**, including the ocean, rivers, streams, and lakes.

![Bathymetry map of East Flower Garden Bank. ](efgboblique.jpg "Bathymetry map of East Flower Garden Bank. ")

Bathymetry map of East Flower Garden Bank.

The term "bathymetry" originally referred to the ocean's depth relative to sea level, although it has come to mean “submarine topography,” or the depths and shapes of underwater terrain.

In the same way that topographic maps represent the three-dimensional features (or relief) of overland terrain, bathymetric maps illustrate the land that lies underwater. Variations in sea-floor relief may be depicted by color and contour lines called depth contours or isobaths.

Bathymetry is the foundation of the science of [hydrography](hydrography.html), which measures the physical features of a water body.  Hydrography includes not only bathymetry, but also the shape and features of the shoreline; the characteristics of tides, currents, and waves; and the physical and chemical properties of the water itself.
# What lives in a kelp forest

## Kelp forests provide habitat for a variety of invertebrates, fish, marine mammals, and birds

![A kelp forest](/facts/kelplives.jpg "Many species of fish and marine mammals inhabit kelp forests for protection and food.")

Many species of fish and marine mammals inhabit kelp forests for protection and food.

In [kelp forests](/facts/kelp.html), the most commonly found invertebrates are bristle worms, scud, prawn, snails, and brittle stars. These animals feed on the holdfasts that keep kelp anchored to the bottom of the ocean and algae that are abundant in kelp forests. Sea urchins will often completely remove kelp plants by eating through their holdfasts. Other invertebrates found in kelp forests are sea stars, anemones, crabs, and jellyfish.

A wide range of fish can be found in kelp forests, many of which are important to commercial fishermen. For example, many types of rockfish such as black rockfish, blue rockfish, olive rockfish, and kelp rockfish are found in kelp forests and are important to fishermen.

A wide range of marine mammals inhabit kelp forests for protection and food. Sea lions and seals feed on the fish that live in kelp forests. Grey whales have also been observed in kelp forests, most likely using the forest as a safe haven from the predatory killer whale. The grey whale will eat the abundant invertebrates and crustaceans in kelp forests. One of the most important mammals in a kelp forest is the sea otter, who takes refuge from sharks and storms in these forests. The sea otter eats the red sea urchin that can destroy a kelp forest if left to multiply freely.

Kelp forests are a natural buffet for birds such as crows, warblers, starlings, and black phoebes which feed on flies, maggots, and small crustaceans that are abundant in kelp forests. Gulls, terns, egrets, great blue herons, and cormorants dine on the many fish and invertebrates living in the kelp. Kelp forests also provide birds with a refuge from storms.

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- The [Elkhorn Slough National Estuarine Research Reserve](https://coast.noaa.gov/nerrs/reserves/elkhorn-slough.html) in California is home to a population of more than 100 sea otters. See for yourself! Visit Elkhorn Slough's real-time [Otter Cam](https://www.elkhornslough.org/ottercam/).

- **Last updated:** 06/16/24  
**Author:** NOAA  
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# Are all algal blooms harmful?

## No, not all algal blooms are harmful.

 [](/facts/predicting-habs.mp4) 

VIDEO: Learn how scientists predict the spread of harmful algal blooms in this video from [Ocean Today](http://oceantoday.noaa.gov/).

There are thousands of species of algae; most are beneficial and only a few of these produce toxins or have other harmful effects. Harmful algal blooms are blooms of species of algae that can have negative impacts on humans, marine and freshwater environments, and coastal economies. These blooms occur when phytoplankton, which are tiny microscopic plants, grow quickly in large quantities while producing toxic or harmful effects on people, fish, shellfish, marine mammals, and birds.

A bloom does not have to produce toxins in order to be harmful to the environment. It can also be harmful by causing anoxic conditions where oxygen is depleted from the water. Blooms can block light to organisms lower in the water column, or even clog or harm fish gills.

Not all algal blooms are harmful, some can actually be beneficial. Phytoplankton are found at the base of the marine food chain therefore all other life in the ocean relies on phytoplankton. Blooms can also be a good indicator of environmental change not only in the water, but also on land.
# What is the world's smallest ocean?

## The Arctic Ocean is the smallest of the world's five ocean basins.

![a polar bear](/facts/arctic.jpg "a polar bear")

A polar bear walks on the frozen surface of the Arctic Ocean. The freezing environment provides a home for a diverse range of creatures.

With an area of about 6.1 million square miles, the Arctic Ocean is about 1.5 times as big as the United States. It is bordered by Greenland, Canada, Norway, Alaska, and Russia. The average depth of the Arctic Ocean is 3,953 feet and it is 18,264 feet at its deepest point.

The Arctic Ocean is almost completely covered with ice for the majority of the year and its average temperature seldom rises above freezing. However, this ocean is anything but barren.

Tunnels within sea ice called brine channels house bacteria and algae that feed flatworms and other tunnel-dwelling creatures. Melting ice also forms ponds on top of the ice that develop into biological communities.

When the ice melts, organisms and nutrients are released into the water. This promotes algae growth below the ice. These algae provide food for small organisms called zooplankton, which are a food source for fish, squid, seals, and whales. Some of these larger creatures, in turn, are preyed upon by polar bears that live on the ice.

When the creatures below the ice die, they sink to the bottom of the ocean and provide nutrients for sponges, sea anemones, and other bottom dwelling creatures. When these communities grow, they provide food once again for larger creatures such as seals, fish, and whales.
# What are phytoplankton?

## Phytoplankton are microscopic marine algae.

![Phytoplankton](/facts/phytoplankton.jpg "Phytoplankton")

Phytoplankton is the base of several aquatic food webs. In a balanced ecosystem, they provide food for a wide range of sea creatures.

Phytoplankton, also known as microalgae, are similar to terrestrial plants in that they contain chlorophyll and require sunlight in order to live and grow. Most phytoplankton are buoyant and float in the upper part of the ocean, where sunlight penetrates the water. Phytoplankton also require inorganic nutrients such as nitrates, phosphates, and sulfur which they convert into proteins, fats, and carbohydrates.

The two main classes of phytoplankton are dinoflagellates and diatoms. Dinoflagellates use a whip-like tail, or flagella, to move through the water and their bodies are covered with complex shells. Diatoms also have shells, but they are made of a different substance and their structure is rigid and made of interlocking parts. Diatoms do not rely on flagella to move through the water and instead rely on ocean currents to travel through the water.

In a balanced ecosystem, phytoplankton provide food for a wide range of sea creatures including shrimp, snails, and jellyfish. When too many nutrients are available, phytoplankton may grow out of control and form harmful algal blooms (HABs). These blooms can produce extremely toxic compounds that have harmful effects on fish, shellfish, mammals, birds, and even people.

The [National Centers for Coastal Ocean Science](http://coastalscience.noaa.gov/) conduct extensive research on harmful algal blooms. Scientists use a range of technologies to predict where and when HABs are likely to form and how they will affect the areas where they occur. Scientists use this information to inform coastal authorities on how to best respond in order to minimize negative impacts.
# What is the largest ocean basin on Earth?

## The Pacific Ocean is the largest and deepest of the world ocean basins.

![the Pacific Ocean](/facts/pacific.jpg "the Pacific Ocean")

The 'Ring of Fire' is defined by a nearly continuous series of oceanic trenches, island arcs, and volcanic mountain ranges and/or boundaries of several plates. It encircles the periphery of the Pacific Ocean Basin. (image courtesy of COMET® program)

Covering approximately 63 million square miles and containing more than half of the free water on Earth, the Pacific is by far the largest of the world’s ocean basins. All of the world’s continents could fit into the Pacific basin.

The Pacific is the oldest of the existing ocean basins. Its oldest rocks have been dated at about 200 million years. The Pacific basin is referred to as the “Ring of Fire” due to intense earthquake and volcanic activity occurring near areas of tectonic plate subduction (where one tectonic plate is forced under another).

The Atlantic basin is the second largest basin, followed by the Indian Ocean basin, the Southern Ocean, and finally the Arctic Ocean basin.