Biology of evechinus chloroticus (Echinoidia: Echinometridae) from different localities

Growth bands were demonstrated in the apical plates of Evechinus chloroticus by grinding horizontal sections which were air dried for several days and treated with lactophenol + 0.5% ferrous ions for a few minutes. Only one dark band was formed each year, during summer.

Evechinus grew considerably faster at Kaikoura than at Kaiteriteri, about 2 cm and 1 cm a year respectively, until growth slowed with increasing age. These differences may relate to food availability.

Numbers in year classes varied considerably, and in some Evechinus populations year classes were absent. Most urchins at Kaiteriteri were less than 6 + years old, but urchins up to 10 years old were aged at Kaikoura. More old urchins were found in deeper populations at Kaikoura, where a number may have been up to 15 years old.

Size‐frequency distributions varied markedly among populations. Distributions appear most influenced by recruitment intensity, and higher growth rates and greater longevity were found in populations with predominantly large urchins, as at Kaikoura.