Functional morphology of burrows and trophic modes of three thalassinidean shrimp species, and a new approach to the classification of thalassinidean burrow morphology

The burrow morphology and feeding behaviour of 3 species of thalassinidean shrimps, Callianassa subterranea, Jaxea nocturna and Upogebia stellata, from organically enriched sediments on the west coast of Scotland were studied using a resin casting technique and from observations in situ and in the laboratory. C. subterranea is primarily a sub-surface deposit feeder but can also supplement its diet by suspension feeding. The burrow consists of a lattice of tunnels and chambers connected to the surface by an inhalant and exhalant shaft and can reach depths of greater than 86 cm. J. nocturna is also a deposit feeder but uses a resuspension technique. Sub-surface material is taken but this species may also scavenge organic material from the sediment surface. The burrow is relatively persistent with a wide spiralling shape. Burrow depths in excess of 92 cm have been recorded. U. stellata is primarily a suspension feeder but has the ability to deposit and resuspension feed. Burrows comprise several connected U- and Y-shaped components and reach depths of at least 26.5 cm. These 3 thalassinidean species exhibit a degree of plasticity in their feeding and different trophic modes can be utilized in order to exploit the most advantageous food source available. The burrow of each species is described in terms of functional morphology with respect to feeding and discussed in relation to existing models of thalassinidean burrow architecture. A new approach to thalassinidean trophic classification based on individual components of burrow morphology rather than the complete burrow is proposed.