BURROW MORPHOLOGY OF THE ECHIURAN WORM MAXMUELLEIA-LANKESTERI (ECHIURA, BONELLIIDAE), AND A BRIEF REVIEW OF BURROW STRUCTURE AND RELATED ECOLOGY OF THE ECHIURA
La. Nickell et al., BURROW MORPHOLOGY OF THE ECHIURAN WORM MAXMUELLEIA-LANKESTERI (ECHIURA, BONELLIIDAE), AND A BRIEF REVIEW OF BURROW STRUCTURE AND RELATED ECOLOGY OF THE ECHIURA, Journal of Natural History, 29(4), 1995, pp. 871-885
The burrow morphology of the echiuran worm Maxmuelleria lankesteri (He
rdman) was investigated in situ using a resin casting technique. Work
was carried out in Lochs Sween and Creran on the west coast of Scotlan
d in predominantly fine mud sediments. Burrow casts typically had only
1 opening, although there is evidence to suggest that a second openin
g may exist. In 58% of burrows, the opening, which was small and funne
l-shaped, was associated with a surface mound reaching up to 20 cm in
height. The tunnel below the burrow opening, the 'neck', was narrow an
d circular in transverse section with a smooth wall, possibly due to t
he action of the mucus-laden proboscis which emerges during feeding. T
he maximum burrow depth recorded was 80 cm and tunnel orientation beca
me more horizontal with increasing depth. In some larger burrows, the
tunnel began to orientate upwards towards its end. Below the neck, the
tunnel was much wider but had a sub-circular transverse section. The
burrows had distinct striations on the walls of lower tunnels, possibl
y caused by movements of the animal within. In some cases, a community
of symbiotic organisms had developed, including polychaetes and 2 spe
cies of bivalve, Mysella bidentata (Montagu) and Saxicavella jeffresii
Winckworth. Evidence of burrow modification by the crustacean Jaxea n
octurna Nardo was noted and gobies, including Gobius niger Linnaeus, w
ere also responsible for some alterations to the upper burrow around t
he opening. Evidence suggested that burrows were permanent structures
which changed little in position.