Marine Life

Wherever you are in the UK, you're never more than 70 miles from the sea. The sea and shoreline are rich and fascinating wildlife habitats, home to creatures of all sizes from the larger marine creatures such as whales, dolphins and seals, countless sea birds and fish, right through to the simplest single celled animals and plants. A separate fact sheet on whales, dolphins and porpoises (cetaceans) is available from The Wildlife Trusts - see further reading section.

Animals and plants which live within the water and are carried by its currents are known as plankton. Plankton plays a vital role in the marine lifecycle. Plant plankton (phytoplankton) is eaten by microscopic animal plankton (zooplankton), and by other animals, which in turn feed predators higher up the marine food chain. Plankton also supplies food direct to very large creatures such as basking sharks and some whales.

Plants Nearly all plants found in the sea around Britain are non-flowering. They range from microscopic species to huge seaweeds (the kelps) which can grow up to five metres long and form underwater 'forests'.

Seaweeds are probably the most familiar form of marine plant life. Many marine animals feed on them and they provide important habitats for others. The only flowering plants in our coastal waters are sea grasses which can grow into extensive shallow sea grass beds.


Animals without backbones (known as invertebrates) are by far the most diverse forms of animal life in the sea, and they include creatures such as sponges, anemones and mussels.

Fish, whales, and other marine animal life which can move independently of the current, are called nekton. There are almost 200 different types of fish around the British Isles. The biggest is the basking shark which is the second largest shark in the world.

Get to know more

If you live in an area with a coastline, joining your local wildlife trust is a good introduction to finding out about marine life. Some trusts have special marine nature reserves where you can see rare plants and animals. For an interesting sample of seashore wildlife, start with rockpools - the marine environment in miniature.


The best time to go rockpooling is at low water on spring tides. These tides are when the water goes out the furthest and occur every two weeks, with neap tides between - when the sea goes out the least. Low water happens twice a day, and you can find out times usually by looking at tide tables and asking locally.

Sheltered shorelines contain a different mix of 'inhabitants' to exposed beaches, and the local wildlife trust will be an excellent source of information on the animals and plants you can

expect to see. A cross-section of likely finds will probably include anemones, prawns, sea squirts, hermit crabs, brittle starfish and fish such as blennies. A net, bucket and margarine tubs for a closer look at your finds will be useful. For your safety and to avoid causing damage you should always follow the seashore code.

The seashore code

  1. Always return rockpool creatures to the place where you found them.
  2. If you move rocks, put them back the same way up in their original place.
  3. It takes years for seaweed to grow, so don't remove it from its anchorage.
  4. Always make sure a shell is empty if you want to take it away.
  5. Don't go rockpooling in windy or rough weather, watch the tide, wear suitable shoes, and tell someone where you're going.

Threats to marine life

Modern fishing methods have caused irrevocable changes to marine life. Some populations of large species, such as tuna in the North Sea, may never recover. Widespread and often illegal use of monofilament gill nets has led to the decline of certain fish such as bass, and the pressures of overfishing have serious consequences for noncommercial wildlife. Capture of species which are not the main target of fishery is a major problem.

Coastal development means that lagoons, salt marshes and small inlets have been infilled and reclaimed, with loss of shellfish beds and fish breeding grounds. The development of coastlines and estuaries for tourism leads to disturbance especially of wading birds.

Many of our everyday packaging products are hazardous to marine life, and a stroll along any beach unfortunately usually includes spotting litter as well as wildlife. Most plastic does not rot, and dead fish and marine animals have been found with plastic bags tangled inside their stomachs.

The plastic loops which hold drinks cans together can trap diving birds and fish, so cut loops before you throw them away or find out where you can recycle them. For more information see The Wildlife Trusts' fact sheet on recycling. Discarded nets and lines from fishing boats can maim or kill all kinds of marine life, and clearing the shoreline of these can be a great help in protecting marine creatures. If you find anything unfamiliar and which you think might be dangerous, do not touch it, but report to the police, or coastguard.

The most worrying pollutants are those which we cannot see and which can enter the food chain with unpredictable effects. For more information see The Wildlife Trusts' fact sheet on pollution.

Further reading

Useful guides to help you identify marine life include:
Spotters Guide to the Seashore (Usborne) and
The Seashore and Shallow Seas of Britain and Europe , AC Campbell (Collins Guide).

Fact sheets from The Wildlife Trusts:
'Looking at Whales and Dolphins',
'Looking at Litter and Recycling',
Looking at River Pollution.

See address below.

If you don't know where to contact your local wildlife trust, then ask The Wildlife Trusts, The Green, Witham Park, Waterside South, Lincoln LN5 7JR Tel: 01522 544400

Did you know...

The shells of barnacles are made up of plates which open up in the water to allow the animal inside to feed.

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