Source: NIWA – National Institute of Water and Atmospheric Research
What do tuangi eat?
Tuangi are filter (suspension) feeders, which means they obtain all their food by straining it from the water. They mainly feed on phytoplankton (microscopic plants).
Using the inhalant siphon, tuangi inhale water to their gills where food and inedible matter is sorted. The inedible matter is discarded as pseudofaeces or redirected to the exhalant water stream and expelled through the exhalant siphon.
Due to their strong filtering abilities, tuangi can also accumulate bacteria and contaminants (e.g., various metals) in their flesh. Depending on the type of contaminant and the amount accumulated, this may pose a human health risk to those consuming the tuangi. Therefore, it is important to collect tuangi from areas with healthy water sources and to avoid harvesting for up to three days after rain events to minimise these risks.
What affects tuangi growth?
There are several factors which can affect the growth of tuangi including:
Age
The growth rate of tuangi tends to slow as they get older.
Food availability
The more food (like plankton) that is available for tuangi, the higher the growth rate.
Position on the beach
The growth rate increases the further you move seaward. This is because the longer tuangi are submerged under water, the longer food is available, and therefore the faster they can grow.
Seasons
Tuangi growth tends to be most rapid over the spring and summer periods.
Environmental conditions
Including temperature and salinity can affect the growth rate.
Most of the factors which can affect the growth rate of tuangi can be attributed back to the age of tuangi or food availability.
