This study examines the barnacle symbionts on 168 blue crabs, Callinectes sapidus, taken from both shallow and deep estuarine environments in the area of Beaufort, North Carolina. The purpose of the study was to quantify the prevalence, intensity, abundance, and spatial distribution of the ectosymbiotic barnacle Chelonibia patula on blue crabs. The proportion of blue crabs fouled was 67%. There was no difference in the prevalence of barnacles on crabs from the shallow versus the deep environment. Results indicate female crabs were significantly more fouled than males. This suggests that the prevalence and intensity of barnacles are dominantly controlled by the migratory habits of the host, since female crabs spend more time in deeper waters of higher salinity, where they are more likely to be fouled by barnacle larvae. The spatial distribution of barnacles on the crab carapaces was controlled by the surface topography of the carapace with more barnacles on the lateral regions than medial. The orientation of the carinal to rostral axes of the barnacles on the carapaces of the host crabs was measured, but no preferred orientation was found. The costs and benefits of epibiosis are reviewed and the barnacle/blue crab relationship appears to be more beneficial to the barnacles than to the host blue crabs.
A new family, Bimuroporidae, is proposed for a clade of Ordovician trepostome bryozoans. The family is united by several characteristics, including a zooidal ontogenetic progression from mesozooid to autozooid and an integrate wall structure. Discriminant and cladistic analyses of colonies from the Ordovician Simpson Group outcropping in the Arbuckle Mountains and Criner Hills of south-central Oklahoma permit the recognition of eight species belonging to this family. Four species assigned to the new genus Bimuropora are described: B. dubia (Loeblich), B. pollaphragmata n. sp., B. conferta (Coryell), and B. winchelli (Ulrich), as well as four species assigned to the genus Champlainopora Ross: C. chazyensis (Ross), C. ramusculus n. sp., C. pachymura (Loeblich), and C. arbucklensis n. sp.
Key, M.M., Jr. 2007: Borings in trepostome bryozoans from the Ordovician of Estonia: two ichnogenera produced by a single maker, a case of host morphology control. Lethaia , Vol. 40, The evolution of borings has shown that the morphology of borings is a function of both the borer and its substrate. This study investigated the effect of bryozoan internal skeletal morphology on the dimensions and distribution of borings. One hundred and forty-three trepostome colonies from the Middle and Upper Ordovician strata of northern Estonia were examined. Of these, 80% were matrix entombed, longitudinally sectioned ramose and hemispherical colonies, and 20% were matrix-free hemispherical colonies that allowed examination of the colony surfaces. Seventy-one percent of the ramose colonies were bored, whereas 88% of the hemispherical colonies were bored. On average, only 8% of colony surface areas were bored out. Borings were more randomly oriented in the hemispherical colonies. In contrast in the ramose colonies, the borings tended to more restricted to the thin-walled endozone and thus parallel to the branch axis. This is interpreted to be a function of the thick-walled exozones controlling to some extent where the borer could bore. Based on morphology, the borings in the hemispherical colonies are referred to Trypanites and those in the ramose colonies to Sanctum . Sanctum is revised to include two possible openings and to recognize that boring shapes were inherently constrained by the thick-walled exozones of the host bryozoan colonies. Both trace fossils were probably produced by a boring polychaete that used the tubes as domiciles. ᮀ Estonia, Ichnotaxa, Ordovician, Sanctum, trace fossils, Trypanites.
Patrick N. Wyse Jackson [wysjcknp@tcd.ie],
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