Mediterranean feather star, Antedon mediterranea
The Mediterranean feather star is a filter feeder that obtains food by straining suspended matter and food particles from water. The star has a stalk that has up to forty tendrils, (threadlike organs) which help the star cling to hard surfaces. The “body” of the star is called a calyx and is shaped like a small cup. This calyx is surrounded by feathery pinnules bearing arms. These arms are quite unique in the fact that they can regenerate if one should get broken off; these arms extend to about 4 inches long and will roll up if danger is detected.
As predicted by the name, this feather star is found primarily in the Mediterranean Sea but has been sighted in the Aegean Seas and the South Coast of Spain. The star favors strong currents and survives best at depths of 260 feet. The strong currents help bring food sources with reach of the arms. The star is nocturnal and lives on rocky or sandy sea floors that have an abundance of algae; the star has been known to live among sea grasses as well. This particular animal grows in clusters clinging to soft corals known as sea whips as well as the sea grasses and sea floors.
The Mediterranean feather star likes to snack on plankton and other food matter that is in the passing sea. Once the star has trapped the food it wraps it in mucus and passes it to the arms by the tubed feet. Once the arms receive the wrap they continue the food on to the central mouth that is located on the upper part of the calyx.
The star looks like it is swimming when it moves around using the tendrils that are located on the stalk. This is done by the arms moving alternately up and down or by “throwing” itself off of propped arms’ tips.
There are female and male Mediterranean feather stars. The gonads (sex glands) are found in the pinnules on the lower part of the arms. Reproduction happens once a year usually during the spring. The process starts with the production of testosterone in the male and estradiol in the female. The fertilized embryos are then attached to the pinnules. From here, the embryos will hatch into barrel shaped larvae. The larvae are free-swimming; movement is made by synchronizing the movement of their groups of finger-like arms.
The new larvae will then produce serotonin and settle down to the sea floor and anchor themselves with stalks — this is where the metamorphosis process begins.
Image Caption: Mediterranean feather star (Antedon mediterranea). Credit: Parent Gery / Wikipedia