U. poseidonis shows two types of movement, swimming and burrowing into the sediment (Watkin, 1939a). Little is known of its life cycle. Generally, breeding behaviour of infaunal amphipods is influenced by location. In deeper waters the spring rise in temperature initiates breeding, while in shallower waters it is induced by tidal phasing (Wolff, 1973; Fish & Fish, 1989). The species of the genus Urothoe may be considered selective deposit feeders. They feed by cleaning sand grains from adhering micro-organisms and detritus (Nicolaisen & Kanneworff, 1969).

In the studied area U. poseidonis is much more common than U. brevicornis. The species is very abundant in the Southern Bight, with highest densities near the coast. U. poseidonis also lives offshore at the shallow Dogger Bank, but is absent from the Oyster Ground. The species is present in the Oosterschelde and several parts of the Wadden Sea. Previously, it has also been found in the Westerschelde (Heip et al., 1986).

In both periods Urothoe poseidonis mainly occurred in the near-coastal zone, with the exception of the eastern coastal zone but with the inclusion of the western Flemish Banks. Whereas the species was only found 15 times and with a maximum density of 50 ind./m2 in the 1976-1986 period, the species had a higher distribution frequency and maximum density (750 ind./m2) in the 1994-2001 period. In the latter period the species was mainly found in the western near-coastal zone.

Balgzand, Basque Coast of Spain, Belgian Exclusive Economic Zone, Bristol Channel, Channel Islands, Dutch Exclusive Economic Zone, English Channel, European waters (ERMS scope), Golfe Normanno-Breton, Grevelingen, Marennes-Oléron bay, Neeltje Jans, Binnenhaven, North Sea, Oléron Island, Oosterschelde, Piet Scheveplaat, Plymouth, Ría de Foz, Ría del Eo, Roscoff, The Wash, United Kingdom Exclusive Economic Zone, Voordelta, Wadden Sea, Westerschelde, Wimereux, Zandkreek

The body of this amphipod is rounded, broad and robust. lts length reaches up to about 6 mm. The eyes are very large in males and contiguous on top of head. The eyes of females are small and oval. The head has a small rostrum. This species is reddish in colour (Lincoln, 1979; Hayward & Ryland, 1990). U. poseidonis differs from the other species of this family described in this atlas, U. brevicornis (q.v.), in having a much bigger carpus of the fifth pereopod.

An amphipod with a relatively rounded, broad and robust body (like Urothoe brevicornis). The eyes are very large in males and contiguous on top of the head. The eyes of females are smaller and oval. The body is reddish in colour. Differs from U. brevicornis in having a much broader fifth pair of legs.

Urothoe poseidonis occurs in fine-grained sediments and reaches a relative occurrence of at least 20% in sediments with a median grain size ranging from 150 to 300 µm. The species avoids muddy sediments (mud content maximum 40%).

U. poseidonis is widely distributed in clean, sandy sediments as commonly found in the Southern Bight and at the Dogger Bank.

Depth range based on 2399 specimens in 1 taxon.
Water temperature and chemistry ranges based on 791 samples.

Environmental ranges
  Depth range (m): 0 - 125
  Temperature range (°C): 7.254 - 10.845
  Nitrate (umol/L): 2.055 - 12.040
  Salinity (PPS): 32.851 - 34.882
  Oxygen (ml/l): 5.996 - 6.605
  Phosphate (umol/l): 0.353 - 0.653
  Silicate (umol/l): 2.091 - 7.673

Graphical representation

Depth range (m): 0 - 125

Temperature range (°C): 7.254 - 10.845

Nitrate (umol/L): 2.055 - 12.040

Salinity (PPS): 32.851 - 34.882

Oxygen (ml/l): 5.996 - 6.605

Phosphate (umol/l): 0.353 - 0.653

Silicate (umol/l): 2.091 - 7.673
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 10
Species With Barcodes: 1