Basket star

Basket star is type of brittle star, which is assigned to the taxonomic suborder Euryalina in the class Ophiuroidea. Basket star is a marine invertebrate animal with a pentaradial symmetry, which lives in deep sea. They are best known for having many-branched slender, interlaced arms. When they are being captured or bothered, Basket star fold over its arms narrowly about the body, presenting the basket shape.

Anatomy
Usually, Basket stars are white, brown or yellow. Basket star is an endoskeleton which is form by calcareous spicules. They also possess a calcium carbonate skeleton. Basket star has five- sided central body (five segments radial symmetry) that length about 8cm (3 in) in diameter. The outline of the body is akin with Asteroidea for ophiuroids have 5 arms which is connected with a central disk. They also have very long and thin tentacles which look like vines. Lengths of these tentacles is about 20 inches (51 centimeters) Most basket stars have 5 long, slender, flexible whip- like arms (some have 6, 7) length up to 38 cm (15 in), which is supported by a vertebral ossicles which is an internal skeleton of calcium carbonate plates. They form dense tangles continuously in the outer part of the arms. Basket star has a skeleton looks like a string of small bones and the bottom which is covered with sucking tube feet, and the vessels of the water vascular system end in tube feet. The water vascular system normally has one madreporite. Basket star’s legs are coiled up into like a knotted ball during the day and stretched out at night like a basket-like shape. There are slits that are openings for pouches at the base of each arm.  Basket star has five jaws in their mouth. There is a short throat, and a huge, blind abdomen cavity which takes up much of the dorsal half of the disk behind the jaws. They neither have an anus nor an intestine. 

Reproduction
Basket star can reproduce both sexually and asexually and they both requires energy to get done. In asexual reproduction, there is a process of a voluntary splitting of the central disc which called fission, and every part regenerating the lacking portion of the disc and arms, forming the entire basket stars.

In sexual reproduction, matured male enlarges white gonads that are accumulated in the bursal slits and matured female enlarges brown gonads. The bursal slits are to be found at the foundation of the arms, on the oral surface and that it is unique.

In asexual fission, male produce other males and female generate females by breaking into several pieces.

Temperature has a repercussion on producing time, and it is known that fission and sexual reproduction happens more often in the warmer months. 

Ecology


Basket star lives in all oceans in the world. from the poles to the tropics. but specifically dwells in muddy or sandy sea bottoms’ rocky areas that have high currents.They are usually seen at nights. Basket star are the most mobile Echinoderms. Brittle star uses their flexible arms, pushing and pulling, acting their spins as traction and moves rapidly. Their predators are usually fish and other invertebrates such as crabs. However, basket star is known for not having many guts except their arms.

Basket star eats microscopic organism such as zooplankton or chaetognaths. When the basket star sees them, they let their arms expands through the water, then their branchlets will stretch out. That will make them more or less vertical to the water current. Basket star will then use microscophic hooks on the arms to seize their food. The captured prey will be wrapped and curl by Branchlets in the vicinity forming a localized knot. Later, the prey will be put out of action because mucus extruded from glands. Then, the basket star transfers the captured prey to the mouth using their knot-laden arms to roll in towards the underside of the disk. When the prey goes into the mouth, all the trapped prey will be removed with a structure inside the mouth which looks like a comb. As the arm is deployed, the prey is then ingested.

Basket star interacts with other organism for the most parts with sponges, soft coral, and Gersemia. Basket star and the host organism benefit each other in such relationships. For instance; sponge is poisonous so other organism dare to touch them, so the basket star hide underneath the sponge, or in ostia, which is a openings in sponges. For the basket star, they gets safety and moreover they can bet food by sweeping over the surface of the sponge removing the large deris clogging the sponge. On the other hand, sponge gets benefits for they get cleaned. Basket star has no direct significance to humans except for purposes of scientific research.

Other
To eat something, Basket stars should let their branchlets to spread out like a fan for control perpendicular to the water current; so they extend their arms. With that, macroscopic organisms are caught on the arms. Then, they roll their arms toward the underside of the disk and eat them. At mouth, the arms remove all the trapped prey with a comb like structure. Then, it is ingested as the arm redeployed.