Comparative Oxygen Consumption of Gastropod Holobionts from Deep-Sea Hydrothermal Vents in the Indian Ocean

ABSTRACT Here we describe novel forms of structural integration between endo- and episymbiotic microbes and an unusual new species of snail from hydrothermal vents in the Indian Ocean. The snail houses a dense population of γ-proteobacteria within the cells of its greatly enlarged esophageal gland. This tissue setting differs from that of all other vent mollusks, which harbor sulfur-oxidizing endosymbionts in their gills. The significantly reduced digestive tract, the isotopic signatures of the snail tissues, and the presence of internal bacteria suggest a dependence on chemoautotrophy for nutrition. Most notably, this snail is unique in having a dense coat of mineralized scales covering the sides of its foot, a feature seen in no other living metazoan. The scales are coated with iron sulfides (pyrite and greigite) and heavily colonized by ε- and δ-proteobacteria, likely participating in mineralization of the sclerites. This novel metazoan-microbial collaboration illustrates the great potential of organismal adaptation in chemically and physically challenging deep-sea environments.

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Unique Characteristics of the Exoskeleton of Bythograeid Crab, Austinograea rodriguezensis in the Indian Ocean Hydrothermal Vent (Onnuri Vent Field)

Integrative and Comparative Biology ◽

10.1093/icb/icz150 ◽

2019 ◽

Vol 60 (1) ◽

pp. 24-32

Author(s):

Boongho Cho ◽

Dongsung Kim ◽

Hyeonmi Bae ◽

Taewon Kim

Keyword(s):

Indian Ocean ◽

Deep Sea ◽

Hydrothermal Vent ◽

Hydrothermal Vents ◽

Mechanical Analysis ◽

X Ray ◽

Sea Bed ◽

The Indian Ocean ◽

Constituent Elements ◽

First Time

Abstract The Indian Ocean hydrothermal vent is a region where a new oceanic crust is formed by magma at the interface of the deep-sea bed over 2000 m in depth. Here we examined for the first time the exoskeleton structure and mechanical properties of the bythograeid crab Austinograea Rodriguezensis living in hydrothermal vents. Scanning electron microscope and energy dispersive x-ray were used for structural analysis, and a nanoindentation system was used for mechanical analysis. The exoskeleton was divided into four layers: epicuticle, exocuticle, endocuticle, and membrane. The thickness of each layer was different from that of other crustaceans previously reported. Additionally, the number of constituent elements, composition ratio, and hardness of each layer were unique among previously studied crabs. This observation indicates that those characteristics might have evolved for creatures with a hard exoskeleton living in the deep-sea hydrothermal vent.

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A new species of the genus Smacigastes Ivanenko & Defaye, 2004 (Tegastidae, Harpacticoida, Copepoda) from the Onnuri Vent Field in the Indian Ocean

Zoosystematics and Evolution ◽

10.3897/zse.96.54507 ◽

2020 ◽

Vol 96 (2) ◽

pp. 699-714

Author(s):

Jong Guk Kim ◽

Jimin Lee

Keyword(s):

New Species ◽

Indian Ocean ◽

Hydrothermal Vent ◽

Hydrothermal Vents ◽

First Record ◽

Cold Seeps ◽

Dichotomous Key ◽

The Family ◽

The Indian Ocean ◽

A New Species

The genus Smacigastes Ivanenko & Defaye, 2004 (Harpacticoida, Copepoda) is the most primitive genus in the family Tegastidae Sars, 1904, occurring in deep-sea chemosynthetic environments, such as hydrothermal vents, cold seeps, whale falls and wood falls. Our exploration of the Onnuri Vent Field, the sixth active hydrothermal vent system in the Central Indian Ridge, resulted in the discovery of a new species in the genus Smacigastes. A detailed morphological analysis of S. pumilasp. nov. reveals that it most resembles S. barti Gollner, Ivanenko & Martínez Arbizu, 2008, described from a hydrothermal vent in the East Pacific Ridge; the new species can be distinguished from the existing species by the 8-segmented female antennule, the absence of an abexopodal seta on the antennary basis, the mandibular exopod represented by a single seta and the exopod of the first leg with five setae. This is the first record of Smacigastes in the Indian Ocean. A dichotomous key to species of the genus Smacigastes worldwide is provided.

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Pararhodobacter marinus sp. nov., isolated from deep-sea water of the Indian Ocean

INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY ◽

10.1099/ijsem.0.003219 ◽

2019 ◽

Vol 69 (4) ◽

pp. 932-936 ◽

Cited By ~ 10

Author(s):

Qiliang Lai ◽

Xiupian Liu ◽

Jun Yuan ◽

Shuchen Xie ◽

Zongze Shao

Keyword(s):

Indian Ocean ◽

Deep Sea ◽

Type Species ◽

Sea Water ◽

Rrna Gene ◽

Chromosomal Dna ◽

Content Type ◽

Deep Sea Water ◽

Link Type ◽

The Indian Ocean

A taxonomic study was carried out on strain CIC4N-9T, which was isolated from deep-sea water of the Indian Ocean. The bacterium was Gram-stain-negative, catalase- and oxidase-positive, rod-shaped and non-motile. Growth was observed at salinities of 0–9% and at temperatures of 4–41 °C. The isolate was able to degrade gelatin but not aesculin. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain CIC4N-9T belonged to the genus Pararhodobacter , with the highest sequence similarity to the only recognized species, Pararhodobacter aggregans D1-19T (96.9 %). The average nucleotide identity and estimated DNA–DNA hybridization values between strain CIC4N-9T and P. aggregans D1-19T were 80.4 and 23.0 %, respectively. The principal fatty acids were summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c), C16 : 0, C18 : 1ω7c 11-methyl, C18 : 0 and C17 : 0. The G+C content of the chromosomal DNA was 66.8 mol%. The sole respiratory quinone was determined to be Q-10. Phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, two unknown phospholipids, four unknown aminolipids and one unknown polar lipid were present. The combined genotypic and phenotypic data show that strain CIC4N-9T represents a novel species within the genus Pararhodobacter , for which the name Pararhodobacter marinus sp. nov. is proposed. The type strain is CIC4N-9T (=MCCC 1A01225T=KCTC 52336T).

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Deep-Sea Challenge: The John Murray/Mabahiss Expedition to the Indian Ocean, 1933-34. A. L. Rice

Isis ◽

10.1086/356179 ◽

1992 ◽

Vol 83 (2) ◽

pp. 356-357

Author(s):

Harold L. Burstyn

Keyword(s):

Indian Ocean ◽

Deep Sea ◽

The Indian Ocean

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New genera, species and occurrence records of Goniasteridae (Asteroidea; Echinodermata) from the Indian Ocean

Zootaxa ◽

10.11646/zootaxa.4539.1.1 ◽

2018 ◽

Vol 4539 (1) ◽

pp. 1 ◽

Cited By ~ 2

Author(s):

CHRISTOPHER L. MAH

Keyword(s):

Indian Ocean ◽

Deep Sea ◽

Western Indian Ocean ◽

Gut Contents ◽

New Genera ◽

Late 20Th Century ◽

The North ◽

Marine Habitats ◽

The Indian Ocean ◽

Occurrence Records

Modern goniasterids are the most numerous of living asteroids in terms of described genera and species and they have important ecological roles from shallow to deep-water marine habitats. Recent MNHN expeditions and historical collections in the USNM have resulted in the discovery of 18 new species, three new genera and multiple new occurrence records from the western Indian Ocean region including Madagascar, Glorioso and Mayotte islands, Walters Shoal, South Africa, and Somalia. This report provides the first significant contribution to knowledge of deep-sea Asteroidea from the Indian Ocean since the late 20th Century. Several deep-sea species, previously known from the North Pacific are now reported from the western Indian Ocean. Gut contents from Stellaster and Ogmaster indicate deposit feeding. Feeding modes of this and other deep-sea species are discussed. Comments are made on fossil members of included taxa. A checklist of Indian Ocean Goniasteridae is also included.

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Micro-forms of hay-silica glass and of volcanic glass

Mineralogical Magazine and Journal of the Mineralogical Society ◽

10.1180/minmag.1968.283.036.14 ◽

1968 ◽

Vol 36 (283) ◽

pp. 1012-1023 ◽

Cited By ~ 12

Author(s):

George Baker

Keyword(s):

Indian Ocean ◽

Deep Sea ◽

Silica Glass ◽

Volcanic Glass ◽

Volcanic Eruptions ◽

North West ◽

South West ◽

Deep Sea Sediments ◽

The Indian Ocean ◽

Lava Fountains

SummaryIn view of recently reported microtektites in deep-sea sediments north-west, south-west, and south of Australia, attention is drawn to the occurrence of minute forms of hay-silica glass among the products of incineration of opal-bearing vegetation in haystacks, and to the minute forms of volcanic glass ejected in lava fountains. These terrestrial micro-forms of glass have properties within the range of those for the fossil glassy bodies named ‘microtektites’. It is possible that the fusion of opal contained in silica-accumulator plants during fierce, prehistoric forest, bush, and grass fires in Australia generated micro-forms of glass that became readily airborne and drifted away in up-currents. Carried by the south-east Trades, they would ultimately descend over the Wharton Basin in the Indian Ocean. Strong to violent northerlies and north-easterlies (Brickfielder Winds) would carry them over the ocean south and south-west of Australia. Thus they could contribute to the deposits of bodies of glass regarded as microtektites in deep-sea sediments. Many microbodies of glass in the Wharton Basin could have had their origin in the Javanese volcanic eruptions.

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