''Echyridella menziesii'', the New Zealand freshwater mussel, also known by its

Māori Māori or Maori can refer to: Relating to the Māori people * Māori people of New Zealand, or members of that group * Māori language, the language of the Māori people of New Zealand * Māori culture * Cook Islanders, the Māori people of the C ...

names kākahi, kāeo, and torewai, is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of freshwater mussel endemic to New Zealand. ''E. menziesii'' is an aquatic

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...

mollusc Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...

in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Unionidae, the river mussels. They were an important food source for the

, but like many freshwater mussels worldwide, are now endangered by pollution and

eutrophication Eutrophication is the process by which an entire body of water, or parts of it, becomes progressively enriched with minerals and nutrients, particularly nitrogen and phosphorus. It has also been defined as "nutrient-induced increase in phytopla ...

of rivers, and the introduction of new species of fish leading to actions via the Treaty of Waitangi claims process.

Distribution

Formerly common in lakes, rivers and streams in New Zealand.

Life cycle

Its reproductive cycle is typical of other freshwater mussels, requiring a host fish on which its larvae (glochidia) parasitise and metamorphose into juvenile mussels – most commonly the kōaro (''Galaxias brevipinnis'')."Kākāhi - the mysterious freshwater mussel"
Greater Wellington Regional Council.

Threats

The destruction or modification of the habitat of the New Zealand freshwater mussel is likely to be a factor in the decline of its population. This modification or destruction of freshwater habitat is also likely to be a factor in the decline in numbers of the mussel's host fish, the kōaro.

Conservation status and efforts

In May 2014 the

Department of Conservation An environmental ministry is a national or subnational government agency politically responsible for the environment and/or natural resources. Various other names are commonly used to identify such agencies, such as Ministry of the Environment ...

classified the New Zealand freshwater mussel under the

New Zealand Threat Classification System The New Zealand Threat Classification System is used by the Department of Conservation to assess conservation priorities of species in New Zealand. The system was developed because the IUCN Red List, a similar conservation status system, had some ...

as "At risk" and "declining".

References

External links

Lectotype specimen
collected by

William Colenso William Colenso (17 November 1811 – 10 February 1899) FRS was a Cornish Christian missionary to New Zealand, and also a printer, botanist, explorer and politician. He attended the signing of the Treaty of Waitangi and later wrote an accou ...

and held at

Museum of New Zealand Te Papa Tongarewa The Museum of New Zealand Te Papa Tongarewa is New Zealand's national museum and is located in Wellington. ''Te Papa Tongarewa'' translates literally to "container of treasures" or in full "container of treasured things and people that spring fr ...