6/18/2023 0 Comments Asterias blastoporeLike the auricularia larva it has a single ciliated band, but it possesses long arms with ciliated bands at the margin.ģ. 21.39H, I) can be regarded as a modification of the auricularia larva of Holothuroid.Ģ. In Holothuria floridana, there is no larval form and the embryo develops directly into a young Holothuroid. saxicola, Psolus phantapus, both of the larval stages may be absent. In Cucumaria planci, the auricularia stage is absent and the embryo transforms directly into the doliolaria stage. This type of larva is also found in crinoids and a few Ophiuroids which possesses ciliated band but no arms.Ħ. In some species of Holothuroids (Order Dendrochirotida e.g., Cucumaria, Thyone etc.), a non-feeding barrel- shaped vitellaria larva is seen.ĥ. 21.39F) is present in Holothuroidea and is characterised in having a single longitudinal ciliated band.Ĥ. The externally bilaterally symmetrical larva (Fig. In Astropecten the brachiolaria stage is absent and the bipinnaria larva metamorphoses directly into adults. The bipinnaria stage is followed by the brachiolaria stage in all Asteroids but direct evidence is only furnished in two cases, e.g., Asterias glacialis and A. These arms are devoid of calcareous rods and have prolongations from the coelomic cavity. These arms are called the brachiolar arms and are beset with warts to help in temporary adhesion.ģ. There are three additional arms which are not ciliated in their courses except in Bipinnaria papillata. It possesses the following special features.Ģ. 21.39E) is present in Asteroidea and is regarded as a modified form of bipinnaria larva. After a short period of free-swimming existence it transforms into a lecithotrophic brachiolaria larva. The bipinnaria is a feeding larva and leads a free-swimming life.
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