Invertebrates

Invertebrates are multi-cellular animals without a backbone. Included are a wide range of types such as arthropods (crustaceans etc.), sponges, jellyfish, sea anemones, unsegmented worms (e.g. nematodes), ribbon worms, segmented worms, molluscs and some small marine groups such as filter-feeding bryozoans.

They are the most diverse species groups and are critical to the functioning of ecosystems, often being the most visible component of marine habitats.
Several marine species are harvested commercially, including shellfish and the Dublin Bay prawn.

Marine invertebrate species are generally well represented around the diverse coastline, particularly in areas such as Strangford Lough and Rathlin Island. Several marine species new to science have been described from Northern Ireland, although none are likely to be endemic.

Invertebrate species often have complex life cycles, with different stages in their life cycle occurring in different habitats. They can be more sensitive to habitat changes than other groups. Declines in some species are poorly understood but many species have undoubtedly been affected by changes in marine habitats from activities like bottom-trawling.