Wednesday, 26 March 2014

Finally some Funiculina

On Wednesday we entered the ‘core’ area of Central Fladen pMPA, an area of particularly special seabed which previous surveys have told us contains all three seapen species. It wasn’t too long before our camera footage revealed many graceful tall seapens Funiculina quadrangularis - much taller, brighter white and less feathery-looking than the slender seapen Virgularia mirabilis.

Tall seapens Funiculina quadrangularis and brittlestars Asteronyx loveni.
Bolocera anemone lurks behind (top) and a hermit crab (Pagurus species)
and white sea urchin Echinus acutus sit beneath the seapen (below) (JNCC/Cefas).

A single sea pen is actually a colony of hundreds of polyps – anemone-like organisms related to soft corals. The feathery structure of each polyp allows them to catch and feed on tiny organisms and dead material in the water, carried past by tidal currents. The polyps’ feathery filaments and branches retract against the main stem of the seapen when disturbed.

Another organism keen to capture the food drifting past is the brittlestar Asteronyx loveni which climbs the tall seapens to gain a good vantage point for feeding. Most of the tall seapens in Central Fladen have had a brittlestar wound around them and some are so smothered that the seapens become weighed down to the floor.

The camera sledge has also revealed plenty of young fish and the impressive northern stone crab Lithodes maja which often shelters beneath the tentacles of the large Bolocera anemones.

A young gadoid fish, probably a haddock Melanogrammus aeglefinus (JNCC/Cefas).
A rockling (Phycidae) with white sea urchins Echinus acutus and a
scallop (Pseudamussium species) (JNCC/Cefas).
Northern stone crab Lithodes maja roaming the mud. This individual
measures about 40 cm across, from leg-tip to leg-tip (JNCC/Cefas).