Dipleurula


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dipleurula

[dī′plu̇r·ə·lə]
(invertebrate zoology)
A hypothetical bilaterally symmetrical larva postulated to be an ancestral form of echinoderms and chordates.
Any bilaterally symmetrical, ciliated echinoderm larva.

Dipleurula

 

a bilaterally symmetrical pelagic larva of the phylum Echinodermata. Development of the dipleurula results in the formation of the echinopluteus larva of sea urchins, of the ophiopluteus of brittle stars, of the bipinnaria and brachiolaria of starfishes, of the auricularia and doliolaria of sea cucumbers, and of the barrel-shaped larva of sea lilies. In structural design the dipleurula is similar to the tornaria of the phylum Enteropneusta and to the larvae of the phylums Pogonophora and Chaetognatha, which attests the phylogenetic kinship of these groups.

References in periodicals archive ?
1997; Nielsen, 2001) could indicate that the common ancestor was enteropneust-like, perhaps with a dipleurula larva.
The structure and function of the ciliary bands of trochophora and dipleurula larvae are completely different, and it seems impossible to derive one from the other.
It has almost universally been concluded that the various types of feeding echinoderm larvae--echinoplu-teus, ophiopluteus, bipinnaria, and auricularia--and the en-teropneust tornaria are all evolved from a planktotrophic dipleurula larva, which was the larva of the common am-bulacrarian ancestor (Byrne et al.
Larvae of deuterostomes and lophotrochozoans are often represented as archetypes, the dipleurula and trochophora, respectively, which have features that are hypothetically ancestral for the larval forms of these two groups.
For some time, interest in the echinoderm and hemichordate larval nervous system and the apical organ has focused on the proposed evolutionary link between the dipleurula larva and the chordate nervous system (21), a hypothesis that now has little support (see discussion in 22).