Kina, Evechinus chloroticus

Kina (Evechinus chloroticus) is a sea urchin that is native to New Zealand. This echinoderm belongs to the family Echinometridae and it has the potential to reach a maximum diameter of 16 to 17 centimeters.

It is scattered throughout New Zealand and in some northern and southern offshore islands. It can be found in shallow waters around 12 to 14 meters deep, although there are also intertidal populations located in the north of both the North and South Islands.

It shows a preference for areas with moderate wave action. In the northern portion of New Zealand, it is found mostly on rocky seafloor areas but also in areas of sandy seafloor. In the South Island, it is also found in abundant densities throughout the fiords.

Some individuals smaller than 1 centimeter in diameter are found attached under both intertidal and subtidal rocks, whereas individuals between 1 and 4 centimeters are found in intertidal and subtidal areas under rocks or within small depressions in rocks. After the sea urchins reach 4 centimeters, they migrate to open areas.

This species is mainly herbivorous, feeding on large brown algae, encrusting substrate and red algae. If kina populations become out of control, kelp forest can be entirely eaten away, leaving the rocks bare, known also as Kina Barrens.

This species has an annual breeding cycle. It becomes sexually mature between 3.5 and 7.5 centimeters in diameter, depending on the population. Gonads are ripe from October and the individuals can spawn from November to February.

Swimming larvae achieve full development in the water column between 4 to 6 weeks. Some other studies regarding larval development report development in the laboratory can take between 22 and 30 days. The larvae of this species are known to settle on substrates that are covered with coralline algal species, such as Corallina officinalis as well as artificial surfaces. Loads of high sedimentation in the water column, such as those that are associated with residential construction, shows a negative effect on settling sea urchins.

Image Caption: New Zealand sea urchin (or kina in the Māori language), Evechinus chloroticus. Credit: Zureks/Wikipedia (CC BY-SA 3.0)