Animals and Plants of the North Sea

Here you can learn about the animals and plants that live in and around the waters of the North Sea. You can read the texts and listen to them. If you want to find out more about an animal or plant, write at least 5 sentences about it. Keep your work together in a folder. (Please don’t simply copy sentences from the text.)

A flounder is a sea fish belonging to the flatfish family. Flounders have a unique body shape. Both eyes are on one side of the head. The other side of the body is white and flat.

Flounders are found in seas around the world, particularly in shallow coastal waters. They feed mainly on small fish and on woodlice, small crustaceans, mussels and worms they find on the seabed. Flounders are known for their ability to change colour to blend in with their surroundings and protect themselves from predators.

Flounders grow to an average length of around 40 cm and weigh about 1 kg. They live near the coast, at depths of up to 100 metres. During the day, they bury themselves in the sand, with only their eyes sticking out. At night, they go in search of food.

A female lays up to two million eggs, from which young larvae hatch after about a week. Most of them are eaten by other marine animals.

Image: pixabay.com

A herring is a small, silvery sea fish belonging to the herring family. Herrings have slender bodies. They can grow up to about 45 cm long and weigh up to one kilogram.

Herring live in large shoals. They feed mainly on plankton, small crustaceans and the larvae of other fish. They often swim through the water with their mouths open, taking in nutrients drifting in the water. Herring are known for their migrations, traveling long distances to mate and spawn.

Herring are preyed upon by cod, tuna, mackerel, seals, and whales. During the day, schools stay mostly in deeper water; at night, they come closer to the surface. Herring can make sounds and hear them too.

The herring became one of the sea’s most important food fish because it is found in large numbers and is easy to catch. Its flesh is rich in protein. Salt keeps it fresh for a long time. It can be fried, smoked, eaten as soused herring or rollmops, and preserved in jars or cans.

Image: pixabay.com

Common sea-lavender is found especially in the salt marshes along the coast. The plant is also called sea lavender. It thrives in salty, sandy soil enriched with silt. It is not related to lilac.

The sea lavender grows to about 20 to 50 cm tall. It flowers in August and September. On the North Sea coast, it sometimes forms whole carpets. It is usually pollinated by insects. Sea lavender spreads through small, nut-like fruits.

The plant has become rare. It has therefore been added to the Red List of endangered plants.

Image: Hamsterkiste

Cockles are also known as Venus shells. They are found all over the world. Their shells have regular ridges. They live in the Wadden Sea in the North Sea, as well as in deeper waters.

Cockles can grow to about 3 to 10 centimetres in length. They can weigh between 10 and 50 grams. Cockles have a foot that they use to burrow 1 to 3 cm into the seabed. By suddenly extending its foot, a cockle can even jump up to 50 cm. Like mussels, cockles filter their food from the water. About 1 litre of water passes through their bodies every hour.

Edible cockles are also used to make ornaments or toys. In the past, lime was made from them.

Image: pixabay.com

Cod live in cold seas, especially the North Atlantic. This fish is also called Atlantic cod. Intensive fishing with trawl nets has made cod rare in some seas.

A cod can grow up to 1.50 m long and weigh up to 100 kg. But only a few reach this size and weight. Cod have a long chin barbel, three dorsal fins, one pelvic fin and two anal fins.

Cod feed on worms, mussels, crabs and small fish. It has been an important food fish since the Middle Ages. It is known for its white, tender flesh and mild flavor. Cod is often used in cooking and is a popular ingredient in dishes such as fish fingers, fish soups and fried fish. Cod can be dried to make stockfish. For this reason, it was an important food store for the winter in the past.

Image: Shannon Keith / U.S. Fish and Wildlife Service – Large group of gray seals on beach (Halichoerus grypus), Public Domain (public domain).

Grey seals are sometimes mistaken for harbour seals. However, they are considerably larger. Males reach a length of 230 cm and weigh 220 kg; females grow to 180 cm long and weigh 150 kg. Harbour seals have rounded heads, whereas grey seals have long heads.

Grey seals have become rare in the North Sea. Breeding stations have been established in the Netherlands and on the Dune of Heligoland to protect the population.

Grey seals can dive to depths of about 140 m and stay underwater for up to 20 minutes. An adult seal eats about 10 kg of fish per day.

Young grey seals are born in February or March, while harbour seals are born in summer. Grey seals can live for around 40 years.

Image: Hans Hillewaert (CC BY-SA 4.0)

The common starfish has five arms. On the underside are suction cups that help it cling on and move around. Starfish live near the shore, at depths of up to about 200 m. They mainly feed on mussels and fish eggs. They can turn their stomach inside out to envelop a mussel and force it to open its shell.

Starfish reproduce by laying eggs, which the females release in large numbers in summer.

Image: Atlantic mackerel (Scomber scombrus), photo: Titus Tscharntke, public domain

Mackerel live near the coasts of the Mediterranean, the North Atlantic and the North Sea. In summer, they are also found in the Baltic Sea. There are many different species, including Atlantic mackerel, Spanish mackerel and king mackerel.

Mackerel grow to about 30 to 50 cm long and can live for up to 17 years. They feed on plankton, fish eggs and fish larvae. But they also hunt young herring, cod and sprats.

Mackerel have no swim bladder, which helps other fish maintain buoyancy. They therefore have to keep moving so they don’t sink. They are highly agile and very fast. Mackerel gather in large schools.

They are popular food fish. They are grilled, smoked, preserved in oil or sold in cans.

Image: Darcone (CC BY-SA 2.0)

They are also known as pile mussels. Their shells grow to between five and ten cm long and are usually blackish brown. The mussels attach themselves to rocks and pilings along the coast. They can tightly close the two halves of their shells with a special muscle. When in danger, they do so suddenly. The mussels can remain in this state for several weeks.

In spring and summer, female blue mussels lay five to ten million eggs. After fertilization, larvae hatch, but almost all of them are eaten by other sea creatures. After about four weeks, the young mussels settle in a fixed spot.

There, adult mussels can easily be collected by fishermen. Blue mussels are considered a delicacy. In some areas, they are therefore cultivated on wooden stakes.

Image: Hamsterkiste

The North Sea shrimp is also known as a brown shrimp, beach shrimp or simply as a shrimp. Female shrimp can grow to about nine cm long, while males are a little smaller. Shrimp have two antennae, two stalked eyes, ten pairs of legs and a tail fan.

Older shrimp prefer deeper water, while young shrimp mostly live in the Wadden Sea. They usually bury themselves just below the surface of the sand. As darkness falls, shrimp go hunting for all kinds of small animals.

They are caught by shrimp trawlers using nets. The prawns are cooked in seawater while still on board. This turns their bodies pink to reddish-brown.

The shells must be removed before the prawns can be eaten. Only one kilogram of meat remains from three kilograms of prawns.

Image: Hamsterkiste

The European glasswort is also called sea asparagus. It is also known as Salicornia.

This plant grows mainly in damp, salty habitats. It can reach further out into the sea than any other plant. Common glasswort cannot survive without salt. It can also withstand flooding. It can grow up to 45 cm tall and has branching green stems. Common glasswort flowers in August and September.

Glasswort is rich in minerals and vitamins. In some regions, it is used as a delicacy in cooking.

Image: Lycaon (CC BY-SA 4.0)

Like the flounder, the plaice is a flatfish. Its eyes are on the right side of its body. Plaice grow to 40 to 70 cm long. They can live for 45 years and weigh up to 7 kg. Plaice can adapt their body colour to match the seabed.

It can also burrow just beneath the surface of the sand when danger threatens. Plaice live near the coast at depths of up to 200 metres. They usually hunt at night. They feed on bristle worms, small crustaceans, mussels, snails and lugworms.

Female plaice lay 50,000 to 500,000 eggs, from which young larvae hatch after two to three weeks.

Plaice is a popular food fish. It is usually caught before it is fully grown. The plaice caught in spring, in particular, is highly prized for its tender flesh.

Image: Hamsterkiste

Marram grass is especially common on the islands in the North Sea. It is deliberately planted in the dunes, where it also grows in sandy soil that is low in nutrients. Its roots form a dense network, protecting the dunes from being blown away. Marram grass is a hardy, upright-growing grass that can reach a height of about 1.20 m. Its dark green leaves are usually rolled up. Marram grass flowers in June and July. Its flowers form dense spikes about 10 cm long.

On the dunes of the North Sea islands, you must stay on the marked paths. Otherwise, small grooves form, and the wind blows the sand away. This exposes the roots of marram grass, causing the plants to die.

Image: M. Buschmann – A young lugworm in his tube. Picture taken at Nationalpark Schleswig-Holsteinisches Wattenmeer, Germany, July 2006, via Wikimedia (Version from August 3, 2006, 08:59)

Lugworms are common in tidal mudflats. They are reddish-brown and grow to about 20 to 40 cm long. The front half of the body is thicker than the back half. They feed on nutrients they find in the sand.

To do this, they take in the damp sand and filter out food in their bodies. They also burrow tunnels about 20 to 30 cm deep into the ground. A single lugworm processes about 25 kg of sand each year.

The worm excretes the undigested remains. Since the worms live very close together, at low tide the floor of the Wadden Sea is covered with little piles.