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A Gastric-Brooding Asteroid, Smilasterias multipara

机译：胃繁殖小行星，Smilasterias multipara

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摘要

The gastric-brooding asterinid sea star, Smilasterias multipara, broods from late August to early November in the shallow sublittoral zone of southeastern Australia. We observed males and females spawning in the laboratory. They shed gametes through gonopores on the sides of the arms. The eggs were orange, about 1.0 mm in diameter, and heavier than seawater. They were externally fertilized by sperm, and placed into the stomach of the female by the tube feet. Twenty-four hours after fertilization, the first cleavage occurred. Cleavage was equal, total, and radial. Development via a non-feeding lecithotrophic brachiolaria was direct, there being no planktrotrophic bipinnaria or brachiolaria larva. Embryos developed, through wrinkled blastula and gastrula stages, into brachiolariae with arms. All of the surfaces of the brachiolaria were covered by cilia. At metamorphosis, a starfish rudiment appeared on the posterior portion of the larval body, while the anterior portion of the larval body was absorbed. Two months after fertilization, metamorphosis was complete. After metamorphosis, juveniles in the stomach grew six pairs of tube feet in each arm. Juveniles, 3 mm in diameter, emerged from the mouth of the mother in early November. Developmental evidence suggests that this asteroid has evolved mechanisms for the protection of larvae and juveniles from gastric digestion.
机译：八月下旬至十一月初，胃孵化的星状海星Smilasterias multipara孵化于澳大利亚东南部的浅沿海地区。我们观察到雌雄在实验室中产卵。他们通过手臂两侧的线孔将配子脱落。卵是橙色的，直径约1.0毫米，比海水重。它们通过精子从外部受精，并通过管脚放入雌性的胃中。受精后二十四小时，第一次卵裂发生。劈开是相等的，总的和径向的。通过非摄食性营养营养性臂状细支气管的发育是直接的，没有营养营养性双pinnaria或臂状细支气管幼虫。胚通过皱纹的囊胚期和胃胚期发育成带臂的腕状鞭毛虫。腕毛的所有表面均被纤毛覆盖。变态时，幼体的后部出现海星残基，而幼体的前部被吸收。受精后两个月，变态完成。变态后，胃中的少年在每只手臂上长出六对管脚。直径3毫米的幼鱼于11月初从母亲的嘴里出来。发展证据表明，这颗小行星已经进化出保护幼虫和幼虫免受胃消化的机制。

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