Color: In situ red-orange, abdomen paler.

This species always lives more or less solitary at the base and on walls of active chimneys, close to aggregates of Rimicaris exoculata, or on mussel beds. The trophic mode is necrophagous, as captures of the shrimps by baited traps indicate. However, the gut contents examined generally contained mainly mineral particles. Ovigerous females collected in August.

The occurrence of this species is confirmed at several locations at Mid-Atlantic Ridge: TAG, Snake Pit, Broken Spur, Logatchev, Rainbow, and Lucky Strike.

Rostrum directed forward or slightly descending, nearly straight or slightly curved dorsally, armed with 14-19 teeth, including 8-12 on rostrum proper and 5-7 moderately large teeth on carapace posterior to level of orbital margin, posteriormost tooth arising from 0.24-0.31 of carapace length; ventral margin armed with 6-9 small teeth. Carapace 0.52-0.65 times as wide as long; postrostral median ridge relatively high, dorsal angle about 150°; pterygostomial tooth relatively strong; branchial region not particularly inflated, slightly convex. Fourth abdominal pleuron with 1-4 (most frequently two or 3) teeth posteriorly. Fifth abdominal pleuron similarly armed with one strong posterolateral tooth and 1-3 additional teeth on posterior margin. Telson narrowed posteriorly, not reaching or reaching posterior margin of uropodal endopod, armed with 6- 8 dorsolateral spines; posterior margin always convex, armed with two pairs of lateral spines and 12-14 plumose setae all longer than mesial pair of lateral spines. Antennular peduncle moderately stout, second segment 1.79-2.05 times longer than wide. Eye with small spiniform tubercle on anterior surface. Antennal scale 1.91-2.04 times longer than wide. Third to fifth pereopods moderately slender; dactyli each with single row of accessory spinules; meri armed with spines on ventrolateral surfaces; ischia also with spines at least in third and fourth pereopods. No epipods on third maxilliped to fourth pereopod. Second to fourth pereopods each with slender, cincinnulate appendix interna.

Carapace length largest male 12.9 mm; largest female 22.3 mm, ovigerous female 13.0 mm. Maximal total length ca. 82 mm.

Holotype for Alvinocaris markensis Williams, 1988
Catalog Number: USNM 234286
Collection: Smithsonian Institution, National Museum of Natural History, Department of Invertebrate Zoology
Sex/Stage: female;
Preparation: Alcohol (Ethanol)
Year Collected: 1986
Locality: Mid-Atlantic Rift Valley, 70 Km S Of Kane Fracture Zone, North Atlantic Ocean
Depth (m): 3437 to 3437
Vessel: Alvin DSR/V

Paratype for Alvinocaris markensis Williams, 1988
Catalog Number: USNM 234287
Collection: Smithsonian Institution, National Museum of Natural History, Department of Invertebrate Zoology
Sex/Stage: female;
Preparation: Alcohol (Ethanol)
Year Collected: 1986
Locality: Mid-Atlantic Rift Valley, 70 Km S Of Kane Fracture Zone, North Atlantic Ocean
Depth (m): 3437 to 3437
Vessel: Alvin DSR/V

Depth range based on 10 specimens in 1 taxon.
Water temperature and chemistry ranges based on 10 samples.

Environmental ranges
  Depth range (m): 1670 - 3650
  Temperature range (°C): 2.523 - 4.255
  Nitrate (umol/L): 17.840 - 22.153
  Salinity (PPS): 34.913 - 35.039
  Oxygen (ml/l): 5.657 - 6.060
  Phosphate (umol/l): 1.148 - 1.496
  Silicate (umol/l): 13.580 - 42.727

Graphical representation

Depth range (m): 1670 - 3650

Temperature range (°C): 2.523 - 4.255

Nitrate (umol/L): 17.840 - 22.153

Salinity (PPS): 34.913 - 35.039

Oxygen (ml/l): 5.657 - 6.060

Phosphate (umol/l): 1.148 - 1.496

Silicate (umol/l): 13.580 - 42.727
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.