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Molgula

Genus of tunicates

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Through Atlantic Ocean

Morphology and development

They are translucent with two protruding siphons, oral and atrial consisting of six and four lobes respectively. They are found subtidally, attached to slow-moving submerged objects or organisms. All species of Molgula have a fluid-filled structure called the renal sac. The renal sac contains nitrogenous wastes, solid concretions composed of weddellite and calcite, and an apicomplexan symbiont called Nephromyces. To further expand on the animals structures, they contain a layer of tunic and given the slight variations existing within the species in terms of forms, they have evolved different bodily and structure colorations as well. For instance in the organisms classified as Molgula manhattensis, the majority have adopted shades in between light yellow and green as depicted by the colored images on the right, with a few being a dusty brown color as well. However, when comparing different species, contrast in colors can be observed.

Furthermore, to delve into the development of the genus Molgula has a wide range of variations among in different species. Many of them are hermaphroditic and can self-fertilize such as Molgula pacifica which are brooded. They can be viviparous like Molgula citrina, from which a larva will pop out, or can have an oviparous egg like Molgula oculata. The way they hatch from the egg can vary such as digestion of the egg membrane or breaking out of it. Molgula are unique ascidians as they can have a tailed tadpoles larvae like most ascidians or an anural larvae. The tailless larvae have reduced characteristics like notochord and tail muscle cells. Molgula have holoblastic cleavage which is present In the species M. pacifica.

Molgula pacifica lacks the tadpole stage in its life cycle meaning it has anural development. Most ascidians undergo urodele development meaning that they have a tailed larval stage. The oocytes and fertilized eggs lack a perivitelline space and test cells that differentiate them with those of the urodele species. Embryos are also similar to urodele ascidians in that they have a similar cleavage pattern and also begin gastrulation at the vegetal pole. There is more modification in cell shape and movement during gastrulation. The muscle cells were absent in the posterior region which is the reason for the lack of the larval tail. The M. pacifica don't have acetylcholinesterase activity on the other hand the urodele species show a high level of acetylcholinesterase activity in the tail muscles. The developmental changes such as modifying the gastrulation and muscle development lead to the elimination of tadpole stage.

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Monotypic taxonTaxonomic group with only one subordinate taxonSpecies descriptionFormal description of a discovered speciesParaphylyType of taxonomic groupIUCN Red ListInventory of the global conservation status of biological speciesSubtropicsGeographic and climate zoneCommon nameName generally used for a taxon, group of taxa or organism(s)