Silén, 1954
Description
Larval body relatively small, up to 0.7 mm, it is opaque and has very small dark brown pigment grains. The pigment is located characteristically in patches at the end of the tentacles and on the preoral lobe. There are two sanguinary globules that merge in older specimens. The maximum number of tentacles is 10, there are never definitive tentacles. The larva is an active swimmer, its pelagic life lasts 12-14 days. The larva develop inside the adult lophophore until it reaches the 4-tentacle stage; thus the adult displays a certain kind of brood protection.
Size
Maximum size ca. 0.7 mm.
Remark
A. hippocrepia is the larva of Phoronis hippocrepia Wright, 1856; the name is kept as a technical name and is used for the larva only.
Distribution in the North Sea
The adult P. hippocrepia occurs burrowing or encrusting, usually at very shallow depths. It is known from several locations in the S and SE North Sea. The larva A. hippocrepia is recorded from the S and SE North Sea, including the Skagerrak (also recorded from the E Channel). It occurs in August-September.
World distribution
Records indicate a world-wide distribution in (sub)tropical and temperate waters.