Overview

Comprehensive Description

Biology/Natural History: This is the second most common Gnathophausia species at bathypelagic depths off southern California, after Neognathophausia ingens (Cowles personal observation). The animal lives below the most severe part of the oxygen minimum layer off southern California, and probably experiences oxygen tensions down to about 10 mm Hg (6.5% of saturation) (Childress, 1975). It is about 80% water by weight. It is negatively buoyant (Childress and Nygaard, 1974) so it must swim constantly throughout its life to maintain its depth in the water. This species seems to have the most primitive foregut of all the mysids examined (De Jong-Moreau and Casanova, 2001). This species may attain sexual maturity at a smaller size in the Pacific than in the Atlantic (Fage, 1941).

Gnathophausia gracilis is sometimes parasitized by an ellobiopsid flagellate protozoan, Amallocystis fascitus, which forms a cluster of white filaments on the ventral side of the anterior abdominal segment. The parasite seems to be associated with the main nerve ganglion in this segment, and is associated with hypertrophy of the ganglion. In N. ingens this parasite also retards sexual maturation such as retarded development of oostegites in females and feminizing changes in males, but these changes may not be as pronounced in G. gracilis.

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Source: Invertebrates of the Salish Sea

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Lophogastrids are bathypelagic, shrimplike crustaceans which differ from true shrimp in that their carapace overhangs but is not actually connected to the posterior thoracic segments. They are not decapods as shrimp are, and, for example, have only one set of maxillipeds instead of 3 and 7 pairs of pereopods instead of 5. The pleopods, with which they swim, are well developed. They have large thoracic gills but no statocysts. As a Peracaridan, female Lophogastrids have long thoracic endopods (called oostegites) which are modified into a basket for carrying eggs and larvae. Gnathophausia gracilis has a large antennal scale which is jointed near the antertior end. The dorsal margin of its carapace is sinuous, the dorsal ridge is interrupted, and it ends posteriorly with a posterodorsally-directed spine (see photo above). The dorsal ridge on the abdominal segments has large dorsally-directed spines. Maximum length up to 14 mm, including rostrum. Females may attain sexual maturity by 5 cm in the Pacific (Fage, 1941), but many larger females than this are found both in the Pacific and the Atlantic which are not mature.
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Source: Invertebrates of the Salish Sea

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Distribution

Geographical Range: Worldwide in tropical and temperate seas. To approximately 40 degrees N in the eastern Pacific, 20 20 degrees S. Especially common in the eastern tropical Pacific.

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Source: Invertebrates of the Salish Sea

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Physical Description

Look Alikes

How to Distinguish from Similar Species: Gnathophausia gracilis can be most readily distinguished from other Gnathophausia species by the large spines projecting dorsally along the dorsal abdominal ridge, along with the sinuous dorsal margin of the carapace with an interrupted ridge. It also has a mid-dorsal spine projecting posterodorsally at an angle at the posterior end of the carapace.
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Source: Invertebrates of the Salish Sea

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Ecology

Habitat

Known from seamounts and knolls
  • Stocks, K. 2009. Seamounts Online: an online information system for seamount biology. Version 2009-1. World Wide Web electronic publication.
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Source: World Register of Marine Species

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Depth range based on 30 specimens in 1 taxon.
Water temperature and chemistry ranges based on 27 samples.

Environmental ranges
  Depth range (m): 275 - 4064
  Temperature range (°C): 1.800 - 11.785
  Nitrate (umol/L): 12.912 - 42.002
  Salinity (PPS): 34.496 - 35.433
  Oxygen (ml/l): 1.874 - 5.438
  Phosphate (umol/l): 1.001 - 2.980
  Silicate (umol/l): 7.674 - 149.828

Graphical representation

Depth range (m): 275 - 4064

Temperature range (°C): 1.800 - 11.785

Nitrate (umol/L): 12.912 - 42.002

Salinity (PPS): 34.496 - 35.433

Oxygen (ml/l): 1.874 - 5.438

Phosphate (umol/l): 1.001 - 2.980

Silicate (umol/l): 7.674 - 149.828
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

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Depth Range: 900-2500 m (off S CA)

Habitat: Bathypelagic

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Source: Invertebrates of the Salish Sea

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Dispersal

Depth range

1000-5225m
  • Muller, H.G. (1993) . World catalogue and bibliography of the recent Mysidacea. 238p
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Source: World Register of Marine Species

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Molecular Biology and Genetics

Molecular Biology

Barcode data: Gnathophausia gracilis

The following is a representative barcode sequence, the centroid of all available sequences for this species.


No available public DNA sequences.

Download FASTA File
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Source: Barcode of Life Data Systems (BOLD)

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Statistics of barcoding coverage: Gnathophausia gracilis

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 2
Specimens with Barcodes: 2
Species With Barcodes: 1
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Source: Barcode of Life Data Systems (BOLD)

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