THE MARINE FAUNA OF THE BLACKWATER ESTUARY 49
Pholadidae
Pholas dactylus Linne
Shells only; recorded from the shores of Mersea Island and St.
Peter's Flats. Many pairs of shells have been found washed up
on the beach at East Mersea in the holdfasts of Laminaria
(9.4.1961). The species may live in some numbers burrowing in
hard mud off the Mersea shore.
Barnea candida (Linne)
Very common, burrowing in hard mud and soft, rotten wood
on the shores and below low water mark in the Blackwater.
Barnea parva (Pennant)
A few paired shells were obtained from pebbles of soft stones
which were dredged inshore of the Colne Bar (24.5.1962).
Zirfaea crispata (Linne)
Some shells, in poor condition, were collected on the shore of
Mersea Island in 1961.
Teredinidae
Teredo novalis Linne Shipworm
Very common and widespread in the Blackwater and Colne
estuaries and along the shores of Essex generally. Boring into
old limber from the middle shore to below low water mark. See
also Davis (1963).
Class CEPHALOPODA
Order Decembranchiata
Sub-Order Teuthoidea
Loliginidae
Alloteuthis media (Linne)
Small specimens occasionally taken in beam trawl hauls during
the summer. Also in otter trawl, Cocum Hills (13.6.1963).
Sub-Order Sepioidea
Sepiidae
Sepia officinalis Linne Common Cuttlefish
A spring visitor to the Blackwater. Dead animals and 'cuttle-
bones' very numerous at East Mersea (24.4.1961), and the living
animals, with their spawn, captured in some numbers in trawl
hauls made at Thirslet (28.4.1961). In 1962, '63, '64 and '65 they
were less common, solitary specimens being taken in trawl hauls
at the mouth of the Blackwater.
Sepiolidae
Sepiola atlantica Orbigny
Occasionally taken in beam trawl samples in early summer.
Small numbers are regularly present each year.