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Marine Habitat Classification

Description of biotope or habitat type

To understand more about what this page is describing, see How to use the classification. See also How to cite.

   Psycropotes longicauda and Oneirophanta mutabilis assemblage on Atlantic mid abyssal mud

Physical habitat description

Salinity Full (30-35 ppt)
Wave exposure
Tidal streams
Substratum Mud - pelagic ooze
Zone Atlantic mid abyssal
Depth Band Biotope depth range 3100 - 4100 m (based on zone); assemblage recorded from 3650 - 5000 m
Other Features

Download comparative physical and biological data. The comparative tables enable a rapid comparison of the species composition and principal physical characteristics between a given set of biotopes.

Distribution of habitat M.AtMA.Mu.HolCom.PsyLon <i>Psycropotes longicauda</i> and <I>Oneirophanta mutabilis</I> assemblage on Atlantic mid abyssal mud

  • Records used to define the biotope (core records)
  • Other records assigned to this biotope, marked as 'certain'
  • Other records assigned to this biotope, marked as 'uncertain'
  • Predicted extent of the level 3 (for sublittoral rock & deep sea) or 4 (for sublittoral sediment) habitat

Point data based on records in the UK Marine Recorder Snapshot. Predicted habitat extent is from UKSeaMap.


This biotope consists of assemblages dominated by holothurians Psycropotes longicauda and Oneirophanta mutabilis on mud. Lavaleye et al. (2002) describe this assemblage from their two deepest stations at 3650 and 4500 m at the base of the Pendragon Escarpment, presumably on pelagic ooze. Billett et al. (2001) describe holothurians as dominating the megafaunal biomass at approximately 5000 m on the Porcupine Abyssal Plain and cite Psychropotes longicauda and Oneirophanta mutabilis, together with Molpadiodemas villosus as contributing substantially to the total holothurian biomass. This assemblage was described based on literature only.


No situation data available.

Temporal variation

No temporal variation data available.

Characterising species

Taxon % of core records where taxon was recorded
Psychropotes longicauda
Oneirophanta mutabiliss
Molpadiodemas villosus

Similar biotopes or habitat types

Occurs shallower in the upper abyssal. Dominant holuthurians are Benthothuria funebris and Oneirophanta.

Classification history of this biotope or habitat type

Classification version Code
2015 (15.03) M.AtMA.Mu.HolCom.PsyLon

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