ORDER
Conica
FAMILY
Aglaopheniidae
TAXONOMY
Sertularia pluma Linnaeus, 1758, North Sea, United Kingdom.
OTHER COMMON NAMES
None known.
PHYSICAL CHARACTERISTICS
The colonies resemble a feather, with a straight stem (hydrocaulus) and two series of alternate branches (hydrocladia). Hydrocaulus monosiphonic up to 5.9 in (150 mm), brown, unbranched or dichotomously branched; basal part athecate, followed by one or two prosegments; remainder internodes, each with three nematothecae and a pseudonematotheca; nodes oblique; hydrocladia alternate, with whitish cormidia separated by transverse nodes. Hydrotheca deep, rim with nine cusps of varied length; intrathecal adcauline septum usually well developed, median nematothecae two-thirds adnate, not reaching the margin of the hydrothecae; lateral nematothecae reaching the rim of the hydrothecae; aperture of nematothecae gutter shaped. Male and female corbulae white, with free costa; male close, with slit-like openings between the costae, female with fused costae and smaller slits. Hydranth small, transparent, cylindrical; hypostome held at level of hydrothecal rim, rounded and low; 10 tentacles emerging at hydrothecal rim.
DISTRIBUTION
Usually considered cosmopolitan, but many other species of the same genus have probably been identified as this nominal species. (Specific distribution map not available.)
HABITAT
It grows on algae, in shallow rocky bottoms.
BEHAVIOR
Nothing is known.
FEEDING ECOLOGY AND DIET
The shape of the colonies is suited to intercept food particles suspended in the water column. The feeding hydranths are small and in great number; they have been observed to beat their tentacles to create a current towards the mouth. This might be an adaptation for active filter feeding of small food items such as phytoplankton.
REPRODUCTIVE BIOLOGY
Colonies dioecious, almost continuously fertile.
CONSERVATION STATUS
Not listed by the IUCN.
SIGNIFICANCE TO HUMANS
None known.
