Assessment of serpulid-hydroid association through the Jurassic: A case study from the Polish Basin

Abstract

The coexistence of sessile, tube-dwelling polychaetes (serpulids) and hydroids, has been investigated. Serpulid tubes bearing traces after hydroids are derived from different stratigraphic intervals spanning the Middle and Upper Jurassic, the rocks of which represent the diverse paleoenvironments of the Polish Basin. Although fossil colonial hydroids classified under the species Protulophila gestroi are a commonly occurring symbiont of these polychaetes during the Late Cretaceous and Cenozoic, they seem to be significantly less frequent during the Jurassic and limited to specific paleoenvironments. The hydroids described here are represented by traces after a thin stolonal network with elongated polyp chambers that open to the outer polychaete tube’s surface with small, more or less subcircular apertures. Small chimney-like bulges around openings are an effect of the incorporation of the organism by in vivo embedment (bioclaustration) within the outer layers of the calcareous tube of the serpulid host. Considering the rich collection of well-preserved serpulid tubes (>3000 specimens), the frequency of bioclaustrated hydroids is very low, with an infestation percentage of only 0.6% (20 cases). It has been noticed that only specimens of the genus Propomatoceros from the Upper Bajocian, Lower Bathonian, Middle Bathonian, and Callovian have been found infested. However, the majority of bioclaustrated hydroids (17 cases) have been recorded in the Middle Bathonian serpulid species Propomatoceros lumbricalis coming from a single sampled site. Representatives of other genera are not affected, which is congruent with previous reports indicating that Protulophila gestroi was strongly selective in the choice of its host. A presumably commensal relationship is compared with the recent symbiosis between the hydroids of the genus Proboscidactyla and certain genera of sabellid polychaetes.

Ultrastructure of the Jurassic serpulid tubes–phylogenetic and paleoecological implications

“…The examined fossils consist of 47 specimens of serpulids representing 12 taxa ( Table 1 ). The studied material has been selected from an ample collection (see Słowiński et al., 2020 ; Słowiński et al., 2022 ) concerning the well-preserved specimens, which allowed for a reliable ultrastructural investigation. All diagenetically altered tubes have been discarded from further studies.…”

Putative hydroid symbionts recorded by bioclaustrations in fossil molluscan shells: a revision and reinterpretation of the cecidogenusRodocanalis

“…2009; Słowiński et al . 2020). Exfoliating the serpulid skeleton, either by weathering or artificially, reveals a reticulate network of stolons and zooid chambers parallel to the growth direction of the serpulid tube (Fig.…”

“…Non‐destructive micro‐computed tomography analyses by Słowiński et al . (2020) have revealed intricate details of this internal arrangement. The serpulid skeletal growth lines are deflected around the stolons and chambers, demonstrating the syn vivo nature of this symbiosis (Scrutton 1975).…”

“…2015; Słowiński et al . 2020). Protulophila appears as a series of semi‐circular to circular apertures in the outer skeleton of the serpulid hosts (Fig.…”

Diverse endobiotic symbiont fauna from the late Katian (Late Ordovician) of Estonia

“…Bioclaustrations are trace fossil cavities, which resulted from embedment of symbiont within the skeleton of the host organism (Palmer and Wilson, 1988;Słowiński et al, 2020). Late Ordovician bioclaustrations left by probable parasites are common in bryozoans both in Baltica and Laurentia (Palmer and Wilson, 1988;Vinn et al, 2014Vinn et al, , 2018.…”