The Archaster Typicus occurs naturally in the Indo-West Pacific region, the Maldives, Hawaii, China, Australia and Singapore.
Dimension and Alimentation
The Archaster Typicus is a starfish with 5 arms that grows up to 15cm in diameter, its preferred natural habitat is a sandy seabed where it spends most of the time wandering the aquarium silting and looking for food, that is based on some organic debris, vegetable matter in decomposition and small invertebrates. It is particularly indicated in aquariums with DSB management method (Deep Sand Bed) where it helps to keep a loose surface by avoiding packaging of the sand due to lack of movement, or in aquariums with Berliner management method, with a few centimeters of sand where the starfish manages to find enough food to live optimally.
The A. typicus has two separated sexual organs with male and female individuals.
It is very difficult to tell the difference between males and females without a special examination of the gonads.
Even conducting the examination of the gonads, several studies have noted a difference in spermatocytes which have a creamy texture and coloring eggs.
The females are larger than males, although they are indistinguishable without further examination.
This species reproduces itself via gonochoric reproduction with external fecundation and asexually by cloning and regeneration.
The starfish reproduces itself pseudocopulation, which means that it shows a behavior similar to copulation, but do not involve sexual union.
During copulation the male is brought into contact with the female through the tip of the arms, using chemical signals to identify the sex of the starfish in contact. After that, the male starfish rise above the female and it adjust itself with alternating arms.
During the release of gametes, the male starfish moves its arms so that Goniopori, both male and female, are synchronized to release their gametes in the water.
The sequence of behavior can be seen in the images below.
The embryos develop into planktonic larvae and then turn into young starfish with stubby pentameric arms.
A. Typicus secretes mucus from the aboral surface glands, where the sand grains adhere when the animal hides in the substrate, forming a veil of coverage.
This stratagem allows an optimal camouflage to protect against predators.
The Starfish Archaster Typicus is not to be included in the IUCN red list, so it’s an animal that does not present risk of extinction.