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Polychaetes

Polychaetes are segmented marine worms. They are one of the most abundant and species rich groups of organisms found in marine sediments. Polychaetes are commonly known as bristle worms due to their hair like appendages known as ‘chaete’ or ‘setae’. They are a highly diverse group of organisms in both their appearance and their ways of life. This diversity relates to their evolutionary history, of which there are long fossils records dating back to the mid Cambrian (>500 million years ago). Some species form tube like structures or burrows in which they live, whilst other species are free living. Some filter feed from the water column, others scavenge or actively hunt prey within the sediment.

As polychaete densities can reach several thousand per square metre they are an important food source for organisms such as fish and wading birds. There are more than 14,000 polychaete species worldwide of which at least 776 species are found in New Zealand (246 are endemic). Certain species are known to respond to changes in fine terrestrial sediment (mud), pollution and organic enrichment in a predictable way, making them good indicators of estuarine health. A large number of different polychaete species have been recorded in Waikato estuaries. The most common polychaete species we monitor are shown below.

Descriptions of species commonly found in Waikato estuaries