Evidence for sublethal predation and regeneration among living and fossil ascophoran bryozoans

Virginia Museum of Natural History Special Publication 01/2008; 15:1-7.


Evidence for partial predation on ascophoran bryozoans was hitherto mainly found in borings of the frontal shield. However, during this and many other studies, borings are only observed rarely. Indeed, many predators (e.g. nudibranch gastropods) are known to gain access to the internal organs via the operculum while leaving no traces of frontal wall damage. This type of predation may, nevertheless, be evidenced by the presence of intramural buds underneath undamaged zooecia, indicated by the presence of one or more orificial rims within the primary one, and implies that the damage occurred during lifetime of the colony. This skeletal signature was observed to occur in Late Cretaceous Acanthostega, as well as in Miocene to Recent Lepraliomorpha, and in Recent Hippothoomorpha. Its infrequent presence may suggest that ascophorans are not important target species for many predators, that not all taxa are able to secrete intramural buds, and/or that only certain types of feeding mechanisms trigger this type of regeneration. Information on feeding habits of modern predators on ascophorans, and reactions of different ascophoran taxa to various types of predation, are needed to verify exactly when and why intramural buds are formed in preyed zooecia.

Download full-text


Available from: Björn Berning
  • Source
    • "The idea of somewhat perennial colonies is supported by the common occurrence of regenerated zooids and nonfunctional zooids with orifices occluded by mineralised closures (Fig. 3e). These features may also reflect the presence and pressure of predators (Berning, 2008), as shown by numerous predation attempts that are visible in the lectotype by means of damaged orifices, and by the presence of a secondary or even tertiary orifice rim Fig. 6 -Cleidochasmidra portisi n. comb. from the Gulf of Noto (Catalogue number PMC R.I.H. B-25b). "
    [Show abstract] [Hide abstract]
    ABSTRACT: The discovery of living and dead specimens of bryozoan colonies currently assigned to Cleidochasmidra canakkalense Ünsal & d’Hondt, 1979 and concomitant examination of Neviani’s type material in the collections of the University of Rome “La Sapienza” allowed the conspecificity between this taxon and Smittia (Phylactella) portisi Neviani, 1895 to be explored. Neviani’s name has priority and the new combination Cleidochasmidra portisi (Neviani, 1895) is here proposed. First SEM photos of C. portisi support this proposal and contribute to illustrate the intraspecific variability of this species relating to the development of ovicells and frontal avicularia, the morphology of the orifice and the peristome, as well as the size of the orifice and the ovicell. The ability of C. portisi to grow beyond its substratum, and to colonise gravel-sized clasts on soft sediments of the intermediate to outer shelf settings occupied by different biocoenoses is described. This extant species, recorded as early as the Early Pliocene, is possibly endemic to the Mediterranean.
    Full-text · Article · Sep 2015 · Bollettino della Societa Paleontologica Italiana
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The cheilostome genera Herentia Gray and Therenia David and Pouyet, placed in the recently established family Escharinidae Tilbrook, were hitherto generally regarded as synonyms of Escharina Milne Edwards. Here we resurrect and define both genera, and revise their eastern Atlantic and Mediterranean species, which turn out to be species complexes. Besides presenting a re-description of the genotype of Herentia, H. hyndmanni (Johnston) from the British Isles, new species from Madeira (Herentia andreasi n. sp.) and the Adriatic Sea (Herentia majae n. sp.) are introduced. The ancestrula of H. hyndmanni, a kenozooid with an almost completely calcified, gymnocystal frontal shield, is here documented for the first time. For Therenia it can be shown that the type species T. porosa (Smitt) from Florida differs from the eastern Atlantic and Mediterranean congeners, all of which were hitherto referred to as this species. Consequently, three new species (Therenia cryptooecium n. sp. from Ghana, Therenia peristomata n. sp. from Madeira, and Therenia rosei n. sp. from the Mediterranean Sea) are described. Both genera show a Paleogene origin and distribution in the Tethyan and Atlantic regions, and persist today in tropical to warm-temperate zones of the Atlantic and Mediterranean Sea. Investigation of poorly studied, low- to mid-latitude regions are likely to yield more new species of Herentia and Therenia.
    Full-text · Article · Jun 2008 · Journal of Natural History
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Rendering developmental and ecological processes into macroevolutionary events and trends has proved to be a difficult undertaking, not least because processes and outcomes occur at different scales. Here we attempt to integrate comparative analyses that bear on this problem, drawing from a system that has seldom been used in this way: the co-occurrence of alternate phenotypes within genetic individuals, and repeated evolution of distinct categories of these phenotypes. In cheilostome bryozoans, zooid polymorphs (avicularia) and some skeletal structures (several frontal shield types and brood chambers) that evolved from polymorphs have arisen convergently at different times in evolutionary history, apparently reflecting evolvability inherent in modular organization of their colonial bodies. We suggest that division of labor evident in the morphology and functional capacity of polymorphs and other structural modules likely evolved, at least in part, in response to the persistent, diffuse selective influence of predation by small motile invertebrate epibionts. KeywordsBryozoa–Asexual growth–Modularity–Polymorphism–Evolvability–Predation
    Full-text · Article · Mar 2012 · Evolutionary Ecology
Show more