Biological zone includes several priority 'traits' or descriptors, i.e. pelagic, benthic and 'deep sea'. There is also cross over with 'environmental position' especially due to 'water column and pelagic'. Mark Costello has demonstrated that many of the terms (e.g infralittoral, circallitoral, abyssopelagic, mesoeplagic etc) have variable definitions and are used inconsistently. He argues therefore, that the depth value is more informative. But it is also clear from the discussions in Crete that for many species we may not have clear depth ranges and/or the 'terms' are commonly used and (possibly) the only information that is available. Hence, we need both. Similarity, many species are recorded as littoral but I'd assume few are record as 10m above Chart datum, especially since the height of the littoral itself is so variable (see below). Therefore, I've rephrased this 'traits' as 'Vertical biological zone (or zonation)' as it describes an organisms place in a vertical gradient from the upper shore to the greatest depths. We also need to find out if there are vertical zones in the terrestrial environment to consider. Environmental position remains valid, as it describes the resident position of an organism relative to its habitat. This is straight forward for epibiota and infauna, but less so for mobile species. I've added text to the definitions to clarify. Adding 'deep sea' here is difficult as both the pelagic and benthic subdivisions could have a 'deep sea' component. Perhaps 'deep sea' sits better under 'Province' , i.e. 'Neritic', 'Oceanic', 'Deep-sea'. Also the definition of 'deep sea' adopted by the deep-sea group does not match EUNIS, where the deep-sea habitat types are defined by the 'edge of the continental shelf or 200m'. Re the EUNIS classification - it uses similar terms , e.g littoral, infralittoral, circalittoral etc but conflates vertical zones with substratum, so that habitat types are defined as littoral rock, littoral mud, littoral sand etc. This has not been out approach. Also, the project plans to label species with the relevant EUNIS habitat type in which they are found as an automated feature, so the EUNIS classification will be covered in it entirety. In Crete we also decide to add 'elevation' to include vertical range above chart datum. This may be relevant to birds and supralittoral and cliff species, nesting seabirds etc. But it should not include species that live at a depth of 20m in a lake that is itself 1000m above chart datum. I've rephrased the definition to reflect this.