Jd. Mckenzie et Ms. Kelly, COMPARATIVE-STUDY OF SUB-CUTICULAR BACTERIA IN BRITTLESTARS (ECHINODERMATA, OPHIUROIDEA), Marine Biology, 120(1), 1994, pp. 65-80
Arm tissues from species of brittlestars from the British Isles and No
rth America were examined by light and electron microscopy for the pre
sence of sub-cuticular bacteria (SCB) which were recorded in 17 of the
19 species studied. Three major groups of SCB could be distinguished
on the basis of their morphology. The bacterial morphology was not cor
related with the host ecology but did appear to be related to the phyl
ogeny of the hosts. Ophiuroids of the same genera had morphologically
similar SCB and this was also generally true of species from the same
family. This indicates the possibility of co-evolution between the SCB
and their hosts. Estimates of SCB load were made for 9 of the species
by direct counting and by quantifying the amount of bacterial endotox
in present in the host tissues. SCB numbers varied interspecifically f
rom 3.7x10(8) to 4.6x10(9) SCB per gram of ash-free brittlestar arm ti
ssue. Endotoxin values ranged from 5.97 to 285 mu g g(-1) ash-free arm
tissue. Calculations suggest that SCB form at least 0.1 to 1% of the
total biomass of the arm tissues. There was considerable intraspecific
variation in SCB load. The possible role and significance of SCB is d
iscussed.