Jakobidae
| Jakoba | |
|---|---|
| Scientific classification | |
| Domain: | Eukaryota |
| (unranked): | Excavata |
| Class: | Jakobea |
| Order: | Jakobida |
| Family: | Jakobidae |
| Genus: | Jakoba |
| Species | |
Jakoba is a genus in the taxon Excavata and currently has only a single described species, Jakoba libera. (Previously described Jakoba incarcerata has been renamed Andalucia incarcerata, and Jakoba bahamensis /Jakoba bahamiensis is not formally described.)
Jakoba are small bacterivorous zooflagellates (jakobids) found in marine and hypersaline environments. They are free swimming trophic cells with two flagella and range between five and ten micrometers in length. Cells rotate along their longitudinal axis to allow for swimming in straight lines unless deformation and “squirming” occurs due to compression in debris. During feeding, bacteria are removed from the water column by a current created by the posterior flagellum. This current causes the bacteria to collect in the groove on the right ventral side of the cell – aiding in ingestion and the creation of food vacuoles.
Cellular components for Jakoba are not particularly unique. They contain a single nucleus found close to the flagellar bases, a single Golgi body, and the organelles are flattened.
Jakoba , however, are of particular interest evolutionarily due to their unique bacterial-like genomes. It has been found that their genomes contain considerably more functional genes than those of other eukaryotic groups and it appears they have retained the ancestral eubacterial RNA polymerase, which has been replaced by viral type polymerase in all other mitochondriate eukaryotes. Overall, jakobid genomes are primitively complex in that they resemble their proteobacterial ancestors more than any other .
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