''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 Co ...

names , , and , is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

freshwater mussel Freshwater bivalves are molluscs of the order Bivalvia that inhabit freshwater ecosystems. They are one of the two main groups of freshwater molluscs, along with freshwater snails. The majority of bivalve molluscs are saltwater species that l ...

endemic to New Zealand. ''E. menziesii'' is an

aquatic Aquatic means relating to water; living in or near water or taking place in water; does not include groundwater, as "aquatic" implies an environment where plants and animals live. Aquatic(s) may also refer to: * Aquatic animal, either vertebrate ...

bivalve Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...

mollusc Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Unionidae The Unionidae are a Family (biology), family of freshwater mussels, the largest in the order Unionida, the bivalve molluscs sometimes known as river mussels, or simply as unionids. The range of distribution for this family is world-wide. It is a ...

, 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 a general term describing a process in which nutrients accumulate in a body of water, resulting in an increased growth of organisms that may deplete the oxygen in the water; ie. the process of too many plants growing on the s ...

of rivers, and the introduction of new species of fish leading to actions via the

Treaty of Waitangi The Treaty of Waitangi (), sometimes referred to as ''Te Tiriti'', is a document of central importance to the history of New Zealand, Constitution of New Zealand, its constitution, and its national mythos. It has played a major role in the tr ...

claims process. It is one of three species of native freshwater mussels identified in New Zealand, the others being '' Echyridella aucklandica'' and '' Echyridella onekaka''.

Taxonomy

The species was first described by

John Edward Gray John Edward Gray (12 February 1800 – 7 March 1875) was a British zoologist. He was the elder brother of zoologist George Robert Gray and son of the pharmacologist and botanist Samuel Frederick Gray (1766–1828). The same is used for a z ...

in 1843, who named the species after

Archibald Menzies Archibald Menzies ( ; 15 March 1754 – 15 February 1842) was a Scottish surgeon, botanist and naturalist. He spent many years at sea, serving with the Royal Navy, private merchants, and the Vancouver Expedition. During his naval expeditions, h ...

, the surgeon of HMS ''Discovery''.

Distribution

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

Ecology

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'') and ''

Gobiomorphus cotidianus The common bully (''Gobiomorphus cotidianus''), or toitoi (Māori), is a fish endemic to New Zealand, and is present throughout the country. There are three other bully species that can be confused with common bullies. There are few characteris ...

''."Kākāhi - the mysterious freshwater mussel"
Greater Wellington Regional Council.

Feeding

While ''Echyridella menziesii'' are parasitic as larvae, juveniles feed by grabbing food using their foot. Adult ''Echyridella menziesii'' are filter feeders, feeding on phytoplankton, animal matter and bacteria. A single mussel is able to filter a litre of water every hour.

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.

History

Kākahi has been a traditional food for

since the Archaic period of

Māori history The history of the Māori began with the arrival of Polynesian settlers in New Zealand (''Aotearoa'' in Māori), in a series of ocean migrations in canoes starting from the late 13th or early 14th centuries. Over time, in isolation, the Poly ...

, and can be found in many early middens. The presence of kākahi around the central North Island lakes may have been a major reason for many central North Island

iwi Iwi () are the largest social units in New Zealand Māori society. In Māori, roughly means or , and is often translated as "tribe". The word is both singular and plural in the Māori language, and is typically pluralised as such in English. ...

to settle around the lakes. The mussels were harvested by using a , a tool used to dredge mussel beds. Kākahi shells were traditionally used as cutting implements, and strings of shells were used as a way to scare rats away from

kūmara The sweet potato or sweetpotato (''Ipomoea batatas'') is a dicotyledonous plant in the morning glory family, Convolvulaceae. Its sizeable, starchy, sweet-tasting tuberous roots are used as a root vegetable, which is a staple food in parts of the ...

(sweet potato) plantations.

Conservation status and efforts

In May 2014 the

Department of Conservation Department may refer to: * Departmentalization, division of a larger organization into parts with specific responsibility Government and military *Department (administrative division), a geographical and administrative division within a country, ...

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 s ...

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 acco ...

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. Usually known as Te Papa ( Māori for ' the treasure box'), it opened in 1998 after the merging of the National Museum of New Zealand ...

. {{Taxonbar, from=Q3017763 Unionidae Bivalves of New Zealand Bivalves described in 1843 Taxa named by John Edward Gray Endemic fauna of New Zealand Endemic molluscs of New Zealand