Going deep
Saturday, June 8, is the 15th World Oceans Day.
Mapping the seafloor
The oceans cover over 70% of the Earth’s surface. The marine ecosystem is the largest and most abundant in the world. But most of the ocean is permanently dark and incredibly difficult to observe. As of 2022, the National Oceanic and Atmospheric Administration had mapped slightly more than 23% of the seafloor in great detail, and even less has been explored with underwater cameras or submersibles. Mapping the seafloor is the first step in exploring the unknown depths of our global ocean.
What is sonar?
Sonar stands for sound navigation and ranging. There are two main types of sonar: active sonar and passive sonar. Active sonar systems emit a pulse of sound into the water, which then bounces off the seafloor, creating an echo. Seafloor depth is calculable using the time difference between creating a sound and receiving its echo.
NOAA Ocean Exploration is an organization dedicated to exploring the deep ocean and filling the gaps in our understanding of the world’s deep waters.
Scientists and governments around the world recognize the importance of making a high-resolution global map of the seafloor. An international collaboration called the Nippon Foundation-GEBCO Seabed 2030 Project aims to produce a high-resolution global map of the seafloor by 2030. It has been calculated that it would take one ship nearly 1,000 years to map the entire ocean at all water depths.
Why is it important?
NOAA scientists say a global seafloor map will benefit us all. We will be able to accurately view the entirety of the Earth’s surface for the first time. Having this data layer will improve global prediction models related to weather and climate, tsunami impact zones and sea-level rise. Countries will be able to prioritize conservation efforts to improve fish stocks and coral reefs. Seeing the seafloor with such clarity will reveal more information than we can imagine.
Oceans quiz
Which ocean has been found to be the saltiest ocean in the world?
- Indian Ocean
- Atlantic Ocean
- Pacific Ocean
- All are salty
Answer: B. Of the five ocean basins, the Atlantic Ocean is the saltiest.
How many islands are in the Pacific Ocean?
- 200
- 1,000
- 2,500
- 25,000
Answer: D. The islands entirely within the Pacific Ocean can be divided into three main groups known as Micronesia, Melanesia and Polynesia.
What special ability do dolphins and toothed whales use to locate food and see underwater?
- Echolocation
- Lateral line
- Electrorecption
- Sonar
Answer: A. Dolphins and toothed whales use echolocation to locate food and see their environment. Some toothed whales sighted in northeast U.S. waters include pilot whales, common dolphins, bottlenose dolphins, Atlantic white sided dolphins, harbor porpoise and sperm whales.
Which of these whale species is one of the world’s most endangered throughout its range? It is estimated to have a population size of about 450 individuals.
- Humpback whales
- Sei whales
- North Atlantic right whales
- Minke whales
Answer: C. The population has been declining since 2010. They feed at or near the surface, which makes them very vulnerable to ship strikes, one of the leading causes of their mortality.
Which of these whales weighs the most?
- Fin whales
- Cuvier’s beaked whales
- Minke whales
- Blue whales
Answer: D. Blue whales weigh up to 330,000 pounds. Fin whales weigh 80,000 to 160,000 pounds, Minke whales weighs up to 20,000 pounds and Cuvier’s beaked whale weigh 4,000 to 6,800 pounds. The blue whale is the largest animal on Earth. They are endangered. One way to protect them and other whales is to report whale sightings using a Whale Alert App.
What is the loudest animal on Earth?
- African elephant
- Sperm whale
- Bottlenose dolphin
- Northern elephant sea
Answer: B. Sperm whales are regarded as the loudest animals on the planet, capable of making sounds up to 230 decibels, louder than jet engines, which are about 150 decibels.
Four or more correct = Jacques Cousteau, three or less correct = Gilligan
Ocean zones
Most ocean life lives above a depth of 660 feet. Nuclear submarines hover around 850 feet below the surface. Whales aren’t usually seen below about 8,200 feet. The Titanic can be found at 12,467 feet.
The deepest part of the ocean is called the Challenger Deep and is located beneath the western Pacific Ocean in the southern end of the Mariana Trench, which runs several hundred miles southwest of the U.S. territorial island of Guam. Challenger Deep is approximately 7 miles deep. It is named after the HMS Challenger, whose crew first sounded the depths of the trench in 1875.
According to National Geographic, if you were to put Mount Everest at the bottom of the Mariana Trench, its peak would still sit around 7,000 feet below sea level.
Even at the very bottom, life exists. In 2005, tiny single-celled organisms called foraminifera, a type of plankton, were discovered in the Challenger Deep.
Sources: NOAA, International Fund for Animal Welfare, Unworldoceansday.org