What does a marine biologist do? (With specialisations)

By Indeed Editorial Team

Updated 6 October 2022

Published 6 May 2022

The Indeed Editorial Team comprises a diverse and talented team of writers, researchers and subject matter experts equipped with Indeed's data and insights to deliver useful tips to help guide your career journey.

Marine biology is a field within life sciences that focuses on organisms living in water. A marine biologist specialises in this science and could focus on research, conservation or even teaching. If you're interested in becoming a marine biologist, you could benefit from knowing the answer to 'What does a marine biologist do?'. In this article, we explain what marine biology is, what a marine biologist does, the tools they use and answer some frequently asked questions.

Related: How to Become a Biologist

What is marine biology?

Within the field of biology, there are many sub-fields that specialise in studying certain types of living organisms. Marine biology is the sub-field primarily concerned with organisms that live in salt water, such as oceans, wetlands and estuaries. This includes both plant and animal life in addition to marine fungi. A marine biologist could therefore study something as small as microscopic plankton to something as large as a blue whale. This also includes the study of marine habitats, their health, and the factors that can affect these environments like pollution and invasive species.

The field of marine biology includes expertise from a wide range of sciences, including biology, chemistry, astronomy, geology, meteorology, zoology, oceanography and ecology. It also affects various industries such as fisheries, tourism, pharmaceuticals and even cosmetics, as marine-sourced materials can bring many benefits. Marine biologists often specialise in a certain sub-field like ichthyology or marine mammalogy.

Related: 11 marine biology jobs (with salaries and primary duties)

What does a marine biologist do?

Knowing the answer to 'What does a marine biologist do?' can help you to determine if this is the right career choice for you. Your responsibilities are going to differ based on your specialism, so understanding these and their respective roles can help you to choose the right path. Here are some common specialisms within marine biology along with a summary describing the work:


An aquarist is a marine biologist who specialises in caring for creatures in aquariums. They help to maintain an appropriate living environment for these animals, feed them and observe their behaviour. Some aquarists might also oversee breeding programmes to preserve certain species. They keep the tanks clean and maintain appropriate temperatures for their inhabitants, sometimes physically entering them to carry out the work. For this reason, many aquarists are also certified divers, which may also be a prerequisite for the job.

In some cases, they capture sick or injured animals and take them to a vet. Moreover, they also participate in setting up exhibits for the public which can include the collection of new specimens. They can also give presentations and raise awareness of certain issues for aquarium visitors.

Related: How to become a zookeeper

Marine mammalogist

A marine mammalogist specialises in studying marine mammals. Moreover, they can also specialise in certain types of marine mammals, such as whales and dolphins, seals and sea lions, manatees and other species like otters. The work involves research and investigation to understand these marine mammals, their life cycles, behaviours and any threats they face. Like many marine biologists, marine mammalogists often have diving certifications so they can conduct research in the natural environment. For instance, they might attach electronic tags to whales or sharks to track their movements and study their migration patterns.

Others might interact frequently with creatures like whales to understand their behaviour. This type of work often involves diving, using scuba gear, video and audio equipment, boats and sonar devices. Alternatively, a marine mammalogist could concentrate on academic research, data analysis and teaching.

Marine biotechnologist

A marine biotechnologist is someone who specialises in the extraction of useful materials from marine plants and animals. This can include aquaculture work, which is the underwater equivalent of agriculture and involves growing marine organisms for food, medicines and fuel. This can involve overlap with other sciences like chemistry, bioinformatics and microbiology. The work could involve a mix of underwater gathering and growing activities, together with analytical and research work in laboratories. As with other specialisms, diving certifications are essential.

Related: How to become a biotechnologist: a step-by-step guide


Ichthyology is the branch of marine biology that specialises in the study of fish species. An ichthyologist is therefore an expert on fish, their life cycles and behaviours. They might work in the natural habitat to collect samples, take measurements and study behaviours which typically necessitates diving certifications. Additionally, they might take these results to a laboratory for further analysis. Alternatively, an ichthyologist might work in a place like a museum to help educate the public, perform research and raise awareness of conservation issues.

Given the abundance of marine life, ichthyologists might occasionally encounter new species. In this case, they may even have the privilege of giving names to these new species. Some ichthyologists teach at universities, where they can carry out research and publish academic papers. In this case, a doctoral degree is typically necessary.

Related: 9 interesting jobs on the ocean (with duties and salaries)

What tools do marine biologists use?

A marine biologist's work can lead them to travel all over the world. They might work physically within the world's marine habitats, near them or within institutions like universities, laboratories, museums and aquariums. Due to the diversity of the work, marine biologists use many tools; some of them are given below:

  • Scuba gear: Although not all marine biologists require a diving certification, the nature of the work means it is often a necessity. Scuba gear enables access to underwater locations to retrieve samples, make observations and take measurements.

  • Sonar: This technology is used for detecting large objects underwater and can help you to measure the depth of the ocean. Marine biologists use sonar technology to observe habitats and find large marine creatures like whales.

  • Hydrophones: A hydrophone is the aquatic version of a microphone and can detect acoustic signals underwater. Marine biologists use them to monitor marine mammals, waves and other underwater activities.

  • Fishing equipment: Marine biologists might use nets and other fishing equipment to catch marine specimens for study. Often, they keep these specimens alive and release them back into the water at a later date.

  • Satellites: The data from satellites can help marine biologists measure the temperature and currents of the world's oceans. They can also use imagery to map coral reefs, coastlines and track tagged marine creatures.

  • Computers: Marine biologists frequently use computers to process and analyse data, display information from sensors and electronic tags, make presentations and store information.

  • Robots: Aquatic robots can be useful for entering marine habitats. They can have cameras and sensors attached thereby allowing marine biologists to remotely explore otherwise inaccessible marine environments.

Frequently asked questions

Below are some frequently asked questions and answers about marine biologists and what they do:

How much do marine biologists earn on average?

The average salary for a marine biologist can vary significantly based on their specialism, location and employer. The national average salary of a marine biologist is £40,060 per year. In contrast, the national average salary of a biotechnologist is £31,740 per year. For an aquarist, the national average salary is £19,633 per year.

Related: How much does a marine engineer make?

Where do marine biologists work?

There are several different employers of marine biologists both in the public and private sectors. Within the public sector, governmental agencies manage fisheries and the environment which may employ marine biologists for investigative and research work. In these institutions, marine biologists might also work on developing regulations for protecting marine environments and conservation areas. In the private sector, there are commercial fisheries, pharmaceutical companies, cosmetics companies, offshore gas exploration companies and NGOs which may also employ marine biologists. There's also academic work available for research bodies, universities and advisory bodies in this profession.

In geographical terms, a marine biologist could work anywhere in the world where there are oceans. They sometimes travel to conduct field research in specific environments, from tropical seas to the arctic. Many of the institutes and universities where marine biologists are based are near coastlines where the work is carried out. A marine biologist might spend time on a ship, underwater, along the coastlines, within laboratories or even in a submarine.

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