Beachcombing along the strandline at Druridge Bay, 16 September: barnacles, wartime concrete, bladder wrack, kelp, keel worm, lichen, limpet, lyme grass, septarian nodules and serrated wrack.
Druridge Bay
Tag: barnacle
Shore Crab
The shell of this common mussel is encrusted with the calcareous tubes of keelworms, which have a prominent ridge, so that they’re triangular in cross section.
The carapace of this shore crab is encrusted with barnacles, these are the barnacle Semibalanus balanoides, which have a diamond-shaped aperture. Between the barnacles at the front of the crab’s shell there’s a flat, pockmarked whitish crust, which looks like sea mat, a marine bryozoan, a colonial animal, filter-feeding from tiny individual cells, like coral.
Like this small frond of bladderwrack seaweed, I picked these up on the beach near the harbour at Bridlington when we spent the day there last month.
Queen Scallop
The lower (right) valve of the queen scallop, Aequipecten opercularis, is flatter than the upper valve.
The ‘front’ or anterior ear of the hinge is always longer than the rear (posterior) ear, which in this specimen appears to have been chipped away still further. This scallop starts its life attached to the sand or gravel of the sea bed but it’s capable of swimming by flapping its shells.
Keel Worm and Barnacles
Amongst the tubes of the keel worm, Pomatoceros triqueter, there are several barnacle shells. The keel worm is an annelid worm, which catches its food by waving its tentacles. It can withdraw into its calcareous tube and protect itself by closing a trapdoor, the operculum, across the entrance.
Sea Mat
Down between the ribs, centre left on this high res scan of the shell, is a small colony of sea mat, a bryozoan, which, like the keel worm, is a filter feeder.