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Bathymetric Zonation.
Echinoderms generally exhibit a marked zonal distribution. The following bathymetric zones are customarily recognized:—
| 1. |
Littoral— |
| (a) |
Eulittoral—0–50 metres |
| (b) |
Sublittoral—50–200 metres. |
| 2. |
Abyssal—200 metres and over The majority of New Zealand echinoderms appear to be rather strictly stenozonal, i.e., each species is confined to a single zone. The few euryzonal forms are referred to later. There appear to be some 44 abyssal species. Since these cannot be utilised in delineating provinces, they are not further considered here, but for reference a check-list follows. |
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| (a) Recorded hitherto only from Kermadec Islands: | |
| Astroschema horridum | Ophiomusium scalare |
| A. salix | Ophiophyllum petilum |
| Ophiacantha cornuta | Solaster torulatus |
| O. vepratica | Pheromonal rigidly |
| Ophioplinthaca plicata | Aglaometra incerta |
| Ophiomoeris clausa | Stiremetra breviradia |
| Ophiurases obstrictus | Thalassometra echinata |
| Amphiura argentea | Glyptometra inaequalis |
| A. lanceolat | Charitometra basicurva |
| Ophiactis flexuosa | C. incisa |
| O. cuspidata | Metacrinus nodosus |
| O. nama | M. wyvillii |
| O. canescens | Saracrinus varians |
| Ophiochiton lentus | Diplocrinus alternicirrus |
| Ophiocoma brevipes | Hypalocrinus naresianus |
| (b) Recorded from near Kermadec Islands and from off East Coast of North Island: | |
| Thaumatometra alternata | |
|---|---|
| (c) Recorded from off North Cape: | |
| Ophiocreas longipes | |
| Astrotoma benhami | |
| Ophiactis hirta | |
| (d) Recorded from off East Coast of North Island: | |
| Ophiacantha vilis | Ophiozonella stellata |
| Ophiomastus tegulitius | Cosmasterias fragilis |
| Amphiophiura ornata | Pourtalesia laguncula |
| Homalophiura irrorata | Temnopleurus reynaudi |
| Ophiocten hastatum | Penta metrocrinus skimpier |
Most of the above records were made by the Challenger Expedition from only a few stations. The lists may require augmentation by one or two species the zonation of which is dubious, and doubtless many species occur which are yet unknown.