Difference between adult echinodiata and larvea

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Over the course of evolution, the acquisition of novel structures has ultimately led to wide variation in morphology among extant multicellular organisms. Thus, the origins of genetic systems for new morphological structures are a subject of great interest in evolutionary biology. The larval skeleton is a novel structure acquired in some echinoderm lineages via the activation of the adult skeletogenic machinery. Previously, VEGF signaling was suggested to have played an important role in the acquisition of the larval skeleton.
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Echinoderms: Adults and Larvae

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Phylogenomic Analyses of Echinodermata Support the Sister Groups of Asterozoa and Echinozoa

The adults are recognizable by their usually five-point radial symmetry , and include such well-known animals as starfish , sea urchins , sand dollars , and sea cucumbers , as well as the sea lilies or "stone lilies". The phylum contains about living species , [4] making it the second-largest grouping of deuterostomes a superphylum , after the chordates which include the vertebrates , such as birds , fishes , mammals , and reptiles. Echinoderms are also the largest phylum that has no freshwater or terrestrial land-based representatives. Aside from the hard-to-classify Arkarua a Precambrian animal with echinoderm-like pentamerous radial symmetry , the first definitive members of the phylum appeared near the start of the Cambrian.
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Describe the differences in symmetry between larval echinoderms and adult echinoderms?

The present study on Eucidaris thouarsi corroborates earlier findings that cidaroids have a characteristic larval form that is different from that of euechinoids and gives the first detailed description of juvenile rudiment formation and metamorphosis in a cidaroid. Larvae of E. Consequently, metamorphosis of cidaroid larvae is simple when compared to that of euechinoids.
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Neuropeptides are an ancient class of neuronal signaling molecules that regulate a variety of physiological and behavioral processes in animals. The life cycle of many animals includes a larval stage s that precedes metamorphic transition to a reproductively active adult stage but, with the exception of Drosophila melanogaster and other insects, research on neuropeptide signaling has hitherto largely focused on adult animals. Accordingly, here we report the first multi-gene investigation of larval neuropeptide precursor expression in a species belonging to the phylum Echinodermata—the starfish Asterias rubens. Expression of only three of the precursors S1, S2, NGFFYamide was observed in bipinnaria larvae but by the brachiolaria stage expression of all eight precursors was detected. An evolutionarily conserved feature of larval nervous systems is the apical organ and in starfish larvae this comprises the bilaterally symmetrical lateral ganglia, but only the S1 and S2 precursors were found to be expressed in these ganglia.
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