Reproduction and lifecycle

Reproduction

Sexes are differentiated for Neocrinus decorus, meaning there are male and female individuals. 

Eggs are produced in large numbers and are held on the pinnules of female individuals. Sperm released into the water stimulates release of the eggs and they are fertilised immediately after. Therefore, Neocrinus produces many young over a week or so, which are released to fend for themselves.

Lifecycle

Once the eggs are released from the parent and fertilised, the resultant embryo attaches to a solid substrate. This may be the arms of the parent crinoid or another surface.

The embryo then develops over several days into a free-swimming, planktonic larva called a doliolaria. After several days these larvae again become fixed and develop a stem, mouth and 5 podia (arm-like structures). This stage is called the cystidean stage.

After several weeks the crinoid reaches the pentacrinoid stage where it forms true arms, pinnules, a complete theca and stem. Finally, the crinoid breaks free from the attachment disc and becomes a stalked, free-living adult enabling the animal to move about and seek out the best feeding areas. 

The animal continues to grow by adding new plates to the stem and arms so that they can reach further into the water column. After a year the animal is fertile and produces either sperm or eggs.

Cyclicity

Most crinoids breed once per year during the spring when both eggs and sperm are released into the water column.