Tetilla polyura

Schmidt, 1870

Species Overview

Tetilla 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: (Tetilla polyura spics) 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.

Remarks

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