| Olavius algarvensis | |
|---|---|
 | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Annelida |
| Clade: | Pleistoannelida |
| Clade: | Sedentaria |
| Class: | Clitellata |
| Order: | Tubificida |
| Family: | Naididae |
| Genus: | Olavius |
| Species: | O. algarvensis |
| Binomial name | |
| Olavius algarvensis | |
Olavius algarvensis is a species of gutless oligochaete worm in the family Tubificidae which depends on symbiotic bacteria for its nutrition.
Olavius algarvensis lives in coastal sediments in the Mediterranean. It was first described from the Algarve Coast of Portugal, [2] but has also been found elsewhere, e.g. off the Italian island Elba, where it co-occurs with another species, O. ilvae. [3] [4] It was the first species of Olavius described from the East Atlantic coast; previously the genus was only known from the Caribbean. [2]
Olavius algarvensis is 12–25 mm long, about 0.25 mm wide, and has between 100 and 150 segments. Like all other species in the genus Olavius, this species has no digestive tract. Instead, the body cavity contains the ventral nerve cord (inside a muscular sheath) and two blood vessels which are surrounded by a "fluffy" layer of chloragocytic cells. They are distinguished from other species of Olavius by having round, flap-like external male papillae that cover the two ventral invaginations of the body wall which contain the male pores (in segment XI), and having small atria that are perpendicular rather than parallel to the body axis. [2] The symbiotic bacteria are located between the cuticle and epidermis, and also in vacuoles within epidermal cells, which often show signs of lysis. The bacteria are absent from the anterior part of the worm and the pygidium, but are found from segment VII or VIII onwards. [3] While cholesterol partially comprises the sterols in their cell membranes, sitosterol, generally a plant sterol, predominates. [5]
Oligochaete worms without any mouth, gut, or nephridial excretory system were first discovered in the 1970s-1980s near Bermuda. [6] They were later found to contain symbiotic chemosynthetic bacteria which serve as their primary food source. O. algarvensis is the species where this symbiosis has been studied in the most detail.
There are five different species of bacterial symbionts in O. algarvensis, which are located under the cuticle of the worm: two sulfide-oxidizing Gammaproteobacteria, two sulfate-reducing Deltaproteobacteria, and one spirochaete. The sulfide-oxidizers gain energy from oxidation of hydrogen sulfide, and fix carbon dioxide via the Calvin cycle. The sulfate-reducers are anaerobes that can reduce sulfate into sulfide, which is consumed by the sulfide-oxidizers. The metabolism of the spirochaete is unknown. [7] Other species of Olavius are also known to have similar symbioses with both sulfide-oxidizing and sulfate-reducing bacteria in the same worm. [4] [8]
The primary sulfur-oxidizing symbiont, known as "Gamma1", is closely related to the primary symbionts of other species of gutless oligochaetes in the Phallodrilinae, and also to the symbionts of nematodes in the subfamily Stilbonematinae. [9]
In addition to hydrogen sulfide, the symbiotic bacteria also allow the worm to use hydrogen and carbon monoxide as energy sources, and to metabolise organic compounds like malate and acetate. These abilities were first discovered by sequencing the genomes and proteomes of the bacteria. [10] [11]
The symbiotic bacteria which live with O. algarvensis have other unique properties. One of the Deltaproteobacteria symbionts, called "Delta-1", is able to produce numerous seleno- and pyrroproteins, which contain the amino acids selenocysteine and pyrrolysine that are sometimes called the 21st and 22nd proteinogenic amino acids. This bacterium has the largest known proteome that has seleno- and pyrroproteins. [12] The symbionts also express the most transposases of any known bacteria. [13]
A trophosome is a highly vascularised organ found in some animals that houses symbiotic bacteria that provide food for their host. Trophosomes are contained by the coelom of tube worms and in the body of symbiotic flatworms of the genus Paracatenula.
Inanidrilus is a genus of marine annelid worms, first described by Christer Erséus in 1979. They are gutless and live in the interstitial of tropical and subtropical seas.
Paracatenula is a genus of millimeter sized free-living marine gutless catenulid flatworms.
Heronidrilus gravidus is a species of oligochaete worm, first found in Belize, on the Caribbean side of Central America.
Inanidrilus reginae is a species of clitellate oligochaete worm in the family Naididae. It was first found in Belize, on the Caribbean side of Central America. It lives in subtidal sand with seagrass.
Olavius finitimus is a species of oligochaete worm, first found in Belize, on the Caribbean side of Central America.
Olavius vacuus is a species of oligochaete worm, first found in Belize, on the Caribbean side of Central America.
Olavius pravus is a species of clitellate oligochaete worm, first found in Belize, on the Caribbean side of Central America.
Bathydrilus egenus is a species of clitellate oligochaete worm, first found in Belize, on the Caribbean side of Central America.
Thalassodrilides bruneti is a species of oligochaete worm, first found in Belize, on the Caribbean side of Central America.
Limnodriloides anxius is a species of clitellate oligochaete worm, first found in Belize, on the Caribbean side of Central America.
Smithsonidrilus appositus is a species of oligochaete worm, first found in Belize, on the Caribbean side of Central America.
Kentrophoros is a genus of ciliates in the class Karyorelictea. Ciliates in this genus lack a distinct oral apparatus and depend primarily on symbiotic bacteria for their nutrition.
Stilbonematinae is a subfamily of the nematode worm family Desmodoridae that is notable for its symbiosis with sulfur-oxidizing bacteria.
Astomonema is a genus of nematode worms in the family Siphonolaimidae. They lack a mouth or conventional digestive tract, but contain symbiotic sulfur-oxidizing bacteria that serve as their primary food source. They live in the marine interstitial habitat.
Nicole Dubilier is a marine microbiologist and director of the Symbiosis Department at the Max Planck Institute for Marine Microbiology since 2013 and a Professor of Microbial Symbioses at the University of Bremen. She is a pioneer in ecological and evolutionary symbiotic relationships between sea animals and their microbial partners inhabiting environments that harbour low nutrient concentrations. She was responsible for the discovery of a new form of symbiosis between two kinds of bacteria and the marine oligochaete Olavius algarvensis.
All animals on Earth form associations with microorganisms, including protists, bacteria, archaea, fungi, and viruses. In the ocean, animal–microbial relationships were historically explored in single host–symbiont systems. However, new explorations into the diversity of marine microorganisms associating with diverse marine animal hosts is moving the field into studies that address interactions between the animal host and a more multi-member microbiome. The potential for microbiomes to influence the health, physiology, behavior, and ecology of marine animals could alter current understandings of how marine animals adapt to change, and especially the growing climate-related and anthropogenic-induced changes already impacting the ocean environment.
Olavius is a genus of oligochaete worms, first described by Christer Erséus in 1984.
Phallodrilinae is a subfamily of clitellate oligochaete worms.
Ainudrilus is a genus of clitellate oligochaete worms.