What is the relationship between Temperature in urchin survival

Sea urchin embryo requires temperature of 23 degrees to cleave, in lower temperatures the embryo cleavage slows down.

Explanation:

Although the sea urchins live in sea water in cold temperature, they require a temperature of around 23 degrees to cleave for fertilisation if this temperature is reduced the process of cleavage slows down eventually depleting the urchin population.