272 Chapter 11
The ability of sphaeromatids to digest wood fragments excavated during
burrowing is unclear, and although gut cellulases have been found, the amount
of wood removed is thought insufficient to sustain the development of one
animal. Food is more likely derived from planktonic filter feeding and grazing
on microorganisms on the surface of the burrows. In this respect, the sphaero-
matids have a lifestyle comparable to the pholads, i.e.using the burrow as a safe
retreat rather than as a source of food.
Active wood-destroying sphaeromatids are found in warm temperate–
tropical waters. They exhibit tolerance to a range of environmental extremes,
including short periods of desiccation in hot conditions when wood is exposed,
plus the ability to withstand very low salinity conditions for days at a time.
Chelurids. The crustacean family Cheluridae is perhaps the least studied of
the marine wood-borers. These amphipods are pale yellow to red in colour,
with a size range of 3–8 mm in length. In some respects, their morphology is
not unlike that of the limnoriids, with a head and segmented thorax, but the
posterior abdomen of the animal is comprised of fused segments and has a
different form and appearance (Figure 6). Chelurids have been described as
the scavengers that live off the waste produced by the limnoriids. They are
invariably associated with limnoriid infestations feeding on faecal pellets
produced by them as well as the wood surfaces of the limnoriid galleries. Like
the limnoriids, the chelurids copulate in the excavated galleries and the female
carries the eggs and developing larvae in a ventral brood pouch. However,
when the young chelurids are released, they search out established galleries
Figure 6Light micrograph of Chelura sp.