The Wadden Sea demonstrates high faunal diversity compared to other coastal wetlands, with over 10,000 species found. The availability of food and the low level of disturbance are essential factors supporting survival of migratory species. Global biodiversity is reliant on the Wadden Sea.

In the last decades two new islands have been formed: the Kachelotplate (170 ha) near the Lower Saxon islands of Memmert and Juist, and a new island of about 14 ha at Norderoogsand in Schleswig-Holstein. The islands evolved from growing sandbanks that are no longer flooded during high tides enabling vegetation to grow. But losses have also occurred and sandbanks have disappeared illustrating the highly dynamic nature of natural processes.

Since the end of the last ice age, the Wadden Sea has evolved over the last 8,000 years. Hence, it is a very young ecosystem in geomorphological and evolutionary terms.

The production of biomass in the Wadden Sea is one of the highest in the world compared to other similar coastal areas, most significantly demonstrated by the numbers of fish, shellfish and birds supported by the area. Its ecosystems sustain wildlife populations well beyond its borders.

The Wadden Sea is one of the most important areas for migratory birds in the world. Around 6 million migratory birds can be found in the Wadden Sea at one time, and an average of 10-12 million pass through it in autumn and spring every year.

The amount of biomass found on mussel beds is 2,000 g per m², compared to about 65 g per m² on tidal flats.