Marine biology

Marine biology is the study of life in the sea. It looks at all the different plants and animals that live in marine habitats, from coastal areas to the deep open ocean. Scientists who work in marine biology study everything from tiny phytoplankton and zooplankton to very large animals like cetaceans (whales).

The ocean covers most of our planet, about 71% of the Earth's surface, and it is home to a huge variety of life. Many of these sea creatures are still unknown to us, and scientists are discovering new ones all the time. Marine life helps shape our planet in many ways. It plays an important role in the oxygen cycle, helps control the climate, and even creates new land in some places.

Sea creatures also give us food, medicine, and materials we use every day. They help support fun activities like recreation and tourism around the world. As we learn more, we are seeing just how connected all life on Earth is, including the life in the ocean. There is still much to discover, especially in the deep parts of the ocean that have not been explored.

Biological oceanography

Main article: Biological oceanography

Marine biology and biological oceanography both study sea life, but they look at it in different ways. Biological oceanography focuses on tiny sea creatures, like plankton, and how they interact with the water's chemistry, physics, and geology. It also looks at how these tiny creatures affect bigger sea animals and the whole ocean ecosystem.

This field studies how plankton grow, move, and eat, and how they help control carbon in the world. It also looks at how tiny microbes fit into the ocean's food chains and how people affect ocean ecosystems.

Marine habitats

Main article: Marine habitats

Marine habitats can be split into two main types: coastal and open ocean. Coastal habitats are near the shore, from the shoreline to the edge of the continental shelf. Most sea creatures live here, even though this area is only a small part of the ocean. Open ocean habitats are far from shore, in the deep water beyond the continental shelf.

We can also divide marine habitats into pelagic and demersal types. Pelagic habitats are in the water away from the ocean floor, often moved by currents. Demersal habitats are close to or on the ocean floor. Some sea creatures, like corals and seaweed, change their habitats to help other animals live there.

Marine life

Main article: Marine life

Many kinds of animals and plants live in the ocean. Marine biology studies these sea creatures, grouping them by where they live instead of what type they are. This means it looks at all creatures tied to the sea, whether they spend their whole lives there or just part of it.

Microscopic life

Main article: Marine microorganism

Tiny sea creatures are very important. They help create food for many ocean animals and play a big role in keeping our planet healthy by recycling air and water. Some of these tiny plants, called phytoplankton, are very numerous and give off much of the oxygen we breathe. Scientists are still learning more about these small sea dwellers.

Plants and algae

Main article: Marine algae and plants

Algae and plants in the ocean are very common and important. They give shelter and food to many sea animals. Large seaweed forests grow underwater, and plants like seagrasses live in shallow waters close to shore.

Invertebrates

Main article: Marine invertebrates

Many sea creatures do not have backbones. These include jellyfish, sea worms, shellfish like squid and octopus, and animals like starfish and sea squirts. Invertebrates are very diverse and numerous in ocean environments.

Fungi

Main article: Marine fungi

There are thousands of types of fungi that live in the sea. They can be found on algae, animals, wood, and even sea foam. These fungi help break down materials and create many useful chemicals.

Vertebrates

Main article: Marine vertebrates

Fish

Main article: Fish

There are over 33,000 kinds of fish, and most of them live in salty water. Fish include both bony fish and cartilaginous fish like sharks.

Reptiles

Main article: Marine reptile

Sea creatures with backbones that are reptiles include sea turtles, sea snakes, and the marine iguana. Most of these reptiles need to come onto land to lay eggs.

Birds

Main article: Seabird

Birds that live near the ocean, such as albatrosses and penguins, are called seabirds. Though they spend most of their time at sea, some like gulls can also be found far inland.

Mammals

Main article: Marine mammal

Marine mammals include whales, manatees, seals, sea otters, and polar bears. All of these animals breathe air and must come to the surface to do so, even if they can stay underwater for long periods.

Subfields

The marine ecosystem is huge, so there are many areas of study within marine biology. Most of these areas focus on learning about specific groups of sea animals, like phycology, invertebrate zoology, and ichthyology. Other areas look at how living in seawater affects sea creatures, how they adapt to salty water, and how changes in the ocean impact marine life. One area studies how oceans and ocean life connect with big environmental issues, like carbon dioxide levels. Recent work in marine biotechnology looks at useful materials from sea life, such as biomolecules and proteins, that might help in medicine or create new materials like biomimetic materials.

By watching the ocean closely, scientists have found sea creatures that could help create treatments for diseases like cancer. For example, a medicine called Ziconotide, used to help with pain, came from a snail that lives in the ocean.

Related fields

Marine biology is a part of biology. It works closely with oceanography, especially biological oceanography, and can be seen as a part of marine science. It also shares ideas with ecology. Fields like fisheries science and marine conservation grow from marine biology, as do environmental studies. Marine chemistry, physical oceanography, and atmospheric sciences are also closely related to marine biology.

Distribution factors

Marine biologists study where different sea creatures live and move throughout their lives. They use special tools like pop-up satellite archival tags, acoustic tags, and data loggers to track these animals. These tools help scientists understand how things like ocean currents, tides, and other ocean conditions affect sea life.

Many sea animals are born, grow up, and live in different places. For example, scientists still don’t fully know where young sea turtles and some sharks go during their first year of life. New tracking technology is helping researchers learn more about deep-sea creatures. This information is important because it helps protect fish populations by deciding when and where fishing should be limited, which supports healthy oceans for everyone.

History

Main article: History of marine biology

The study of marine biology began a long time ago. Aristotle made many observations of sea life around Lesbos, which helped start many future discoveries. Later, in 1768, Samuel Gottlieb Gmelin wrote the first book about sea plants, using a new way to name living things created by Linnaeus.

The British scientist Edward Forbes is often called the founder of marine biology. In the 1800s, many scientists began exploring the oceans more. Important trips, like the one made by HMS Beagle where Charles Darwin developed his ideas about how animals change over time, helped scientists learn a lot about ocean life. Another big trip was made by HMS Challenger, which showed there were many different kinds of animals in the deep sea.

Creating special labs where scientists could study sea creatures was very important. The oldest lab is Station biologique de Roscoff in France, started in 1859. In the United States, Scripps Institution of Oceanography began in 1903, and Woods Hole Oceanographic Institute started in 1930. New tools like special diving gear and underwater vehicles let scientists explore deeper parts of the ocean.