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Asterina stellifera has a defined annual and synchronous reproductive cycle. This cycle is affected by seawater temperature and day-length, they increase chances of fertilization by controlling gametogenesis (a process in which one cell splits to form four more cells).
Asexual reproduction in starfish takes place by fission or through autotomy of arms. In fission, the central disc breaks into two pieces and each portion then regenerates the missing parts. In autotomy, an arm is shed with part of the central disc attached, which continues to live independently as a "comet", eventually growing a new set of arms.
Starfish or sea stars are star-shaped echinoderms belonging to the class Asteroidea (/ ˌ æ s t ə ˈ r ɔɪ d i ə /). Common usage frequently finds these names being also applied to ophiuroids, which are correctly referred to as brittle stars or basket stars. Starfish are also known as asteroids due to being in the class
The starfish engages in external fertilization in which the female releases the eggs and the male releases the sperm. Fertilization occurs in the water column. Its breeding season is the summer. During this time, male and female starfish can be found extremely close or even on top of one another.
The starfish is found on hard bottoms and under stones and seaweed where it mainly feeds on other echinoderms and on bivalve molluscs. [3] In most of its range, it undergoes sexual reproduction in the winter, while in the summer, it proliferates by asexual reproduction . [ 4 ]
Underside of a sunflower sea star. Sunflower sea stars can reach an arm span of 1 m (3.3 ft). They are the heaviest known sea star, weighing about 5 kg. [4] They are the second-biggest sea star in the world, second only to the little known deep water Midgardia xandaros, whose arm span is 134 cm (53 in) and whose body is 2.6 cm (roughly 1 inch) wide. [7]
Fertilization is the fusion of gametes to produce a new organism. In animals, the process involves a sperm fusing with an ovum, which eventually leads to the development of an embryo. Depending on the animal species, the process can occur within the body of the female in internal fertilization, or outside in the case of external fertilization.
An echinoderm (/ ɪ ˈ k aɪ n ə ˌ d ɜːr m, ˈ ɛ k ə-/) [2] is any animal of the phylum Echinodermata (/ ɪ ˌ k aɪ n oʊ ˈ d ɜːr m ə t ə /), which includes starfish, brittle stars, sea urchins, sand dollars and sea cucumbers, as well as the sessile sea lilies or "stone lilies". [3]