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Schmidt, 1870

Species Overview

Craniella polyura Schmidt (1870) is an elongate upright globular sponge with an optically smooth surface. Many specimens exhibit a sort of "tail", i.e. masses of long spicules with which the sponge is rooted to the substrate. It is light yellowish or brownish in colour and has a hard consistency. It is a northern deep water species.

Taxonomic Description

Colour: Light yellow or brown.
Shape, size, surface and consistency: Upright globular-elongate sponge with more or less smooth surface, which may be faintly conulose. Size up to 7 cm high. Typically provided with a root system of long spicule bundles with which it is attached to the substrate. Oscules few, on top or slightly excentric on the side. Consistency hard, tough.
Spicules: (craniella_polyura_spics.jpg) Megascleres: Oxeas in two size classes: small ones from the cortex: 340-1800 x 3-10 µm; large ones: 1500-5000 x 10-35 µm; protriaenes, with shaft 1300-8700 x 3-5 µm, cladi 70-200 µm; anatriaenes with shaft up to at least 10, 000 x 6-8 µm, cladi 50-120 µm. Microscleres: Sigmaspires, often with centrotylote swelling: 13-20 µm.
Skeleton: Cortical skeleton a radiate arrangement of megascleres, with small oxeas concentrated in it. Choaonosomal skeleton radiating bundles of megascleres with scattered microscleres.
Ecology: On pebbles and rocks in deep water, 25-595 m.
Distribution: Iceland, Norway; Arctic.
Etymology: polyurus (Greek) = with many tails, referring to the root system.
Type specimen information: The only recorded type material left is a slide in the Natural History Museum, London: BMNH 1870:5:3:50, 179.


The relatively smooth surface and the characteristic root system make this an easily recognizable species. Further species of Craniella from much deeper waters off Norway are C. abyssorum (Carter), which has unusually large microscleres (up to 40 µm) and C. infrequens (Carter) which has dichotriaenes.
Source: Koltun, 1966

Craniella polyura