Sipuncula Research Articles

Evolutionary trend of Zoophycos morphotypes from the Upper Cretaceous–Lower Miocene in the type pelagic sections of Gubbio, Italy

About 200 Zoophycos specimens, including 90 specimens studied in detail, have been analysed in the continuous Upper Cretaceous–Lower Miocene pelagic sedimentary type sections of the Gubbio area (the Contessa Highway, Contessa Quarry and Bottaccione sections, Northern Apennines). The sediments are reddish to grey limestones and marls of the Scaglia Group and marls with volcaniclastic deposits of the Bisciaro Formation. The aim was to examine the evolutionary trend of what is probably the most debated trace fossil of all time, from the Upper Cretaceous to Lower Miocene. Despite having been found in beds ranging from the Cambrian to the present, no consensus has been reached regarding mode of construction, tracemaker or ethological explanation for Zoophycos. Four Zoophycos morphotypes are recognized at Gubbio showing variations of major and minor lamellae, apex, lobes and whorls: the Cretaceous–Eocene cone-shaped type 1, the Upper Eocene–Middle Oligocene helicoidal type 2, the Oligocene lobate type 3 and the Upper Oligocene–Lower Miocene flat type 4. The very high ichnodensity in some beds (hundreds of specimens in discrete levels of the Bisciaro Formation, now destroyed by quarrying) seems to find explanation in abnormal concentrations of phytodetritus and organic matter on the seafloor in some periods. This very high abundance in discrete levels reflects a change in sedimentation and seafloor conditions at pre-flysch deposition. Due to such high ichnodensity, many adjacent specimens display deformed outer margins. Taphonomic analysis shows a variation of whorls, laminae and U-shaped lobes, reflecting ontogenetic development of the tracemaker(s) (?sipunculid worms).

SIPÚNCULOS (SIPUNCULA) DEL GRAN CARIBE: LISTA DE ESPECIES Y BIBLIOGRAFÍA

Sipunculans, or “peanut worms”, are marine invertebrates with high importance in rock dissolution processes, and because they are an important source of food for other marine species. A search of all literature about recorded families, genera and species for the Grand Caribbean was done. The region comprises between the limits from South Carolina, in the United States, to the Northern littoral of Brazil, including the Gulf of Mexico, Major and Lesser Antilles, as well as Center and South American coasts. The revision includes as much published information as possible, both electronically and in hard copy, and was organized and listed in alphabetical and not phylogenetic order. Species that are not from the region where differentiated such as synonymies, in order to offer an idea about the taxonomic problems that the group has. 84 specie names where found, divided into 14 genera and 6 families. From the 84 names that where found, only 23 names correspond to valid species; 10 out of the 84 names that where found do not have suffiient information. In these terms, the group is organized through the standardized and systematic preliminary order. It is expected that this list becomes an important source of knowledge for sipunculans in the Caribbean and other close regions.

Cryptic species in Pacific sipunculans (Sipuncula: Phascolosomatidae): east‐west divergence between non‐sister taxa

Cryptic diversity, i.e. diversity observable in genetic but not in morphological traits, is prevalent in marine invertebrates and presents one of the greatest obstacles to obtaining accurate estimates of species richness. Sipunculans, commonly called peanut worms, are marine annelids in which high levels of cryptic diversity have previously been documented. In this study, we use genetic identification techniques to examine divergence of two lineages of Pacific sipunculans, both known under the name Phascolosoma agassizii. One lineage is isolated to the eastern Pacific coast while the other one inhabits the western Pacific coast. These clades are reciprocally monophyletic and are not recovered as sister taxa, suggesting relatively early divergence within Phascolosoma. Furthermore, we did not find support for a genetic distinction between the western Pacific Phascolosoma agassizii agassizii and Phascolosoma agassizii kurilense, a subspecies reported from the Kuril Islands. Considering that the type locality for P. agassizii is in the Eastern Pacific, we suggest that the western clade, including the samples from the Kuril islands, represent a new, undescribed species.

Đặc điểm phân bố và môi trường sống của loài Sâm đất (Phascolosoma arcuatum, Gray 1828) tại rừng ngập mặn Cần Giờ

The results of the study on the distribution and environmental characteristics of Peanut Worms (Phascolosoma arcuatum, Gray 1828) in Can Gio mangrove forest show that: Peanut Worms live in the areas which have flood level < 1m, flood time < 30%, the topography from 0.8m to 1.7m and in the depth from 10 cm to 30 cm. They live in the soil from silty clay loam to clay which is quite porous, high humid, from acidic to neutral, organic-rich, heavy salty and less aluminous. The average density of the Peanut Worms is 7.44 individual/m2. Peanut Worms density in mixed mangrove forest is higher than that in planting Rhizophora apiculata forest and depends on the compartments. It is forecasted that the distribution area of Peanut Worms in Can Gio mangrove forest is about 24,323 ha and the caches of Peanut Worms are about from 285,600 kg to 535,500 kg/year.

Optimal dietary protein to energy ratio for juvenile peanut worm Sipunculus nudus Linnaeus

The optimal dietary protein to energy (P/E) ratio for juvenile peanut worm Sipunculus nudus Linnaeus (initial average weight 46.16 ± 0.07 mg) was determined using practical diets in a 3 × 3 factorial experiment. Three dietary protein levels (38, 43, and 48 %) and three lipid levels (6, 9, and 12 %) were tested, yielding P/E ratios of 19.5–26.4 mg protein kJ−1. Each diet was fed to juveniles in three plastic tanks (65 × 55 × 45 cm) for 56 days. S. nudus juveniles fed a diet containing 43 % protein and 9 % lipid, yielding a P/E ratio of 23.1 mg protein kJ−1, presented the highest specific growth rate among the treatments (P 0.05). Carcass protein content improved as dietary protein increased at each lipid level, and carcass lipid content improved as dietary lipid increased at each protein level. The results indicate that feeding S. nudus a diet containing 43 % protein and 9 % lipid, with a P/E ratio of 23.1 mg protein kJ−1, leads to optimal growth performance.

A new rhizangiid genus from the Miocene of North America (Sclerangia n. gen.; Florida, USA)

ABSTRACT The colonial rhizangiid genus Sclerangia n. gen. is described from the Miocene of the USA (Chipola Formation, Florida). The new genus is characterized by plocoid to subcerioid polyp integration, cylindrical to subcylindrical or tympanoid corallites, and an endotheca that is generally absent or made of a very small number of vesicular dissepiments. Compared to other rhizangiid genera, the new taxon is characterized by rather weakly dentate septa. In addition, the new genus differs from all the rhizangiid genera by its consistent encrustation of dead gastropod shells that are inhabited by sipunculid worms.

Ultrastructural observations on spermiogenesis in the peanut worm, Phascolosoma esculenta (Sipuncula: Phascolosomatidea)

Ultrastructural characteristics of spermiogenesis in the peanut worm, Phascolosoma esculenta (Phascolosomatidea), were observed by transmission electron microscopy (TEM). The spermiogenesis principally occurs in the coelom and can be divided into three stages (the early, middle and late stages) based on the chromatin morphology, acrosome development, spermatozoon midpiece and flagellum formation. Spermatids within a given spermatid mass develop synchronously. With the spermiogenesis proceeding, the spermatid masses become loosely structured, and later, adjacent spermatids are interconnected at one extremity of the cells. Gradually, condensation of the chromatin accelerates and is almost completed in late spermiogenesis, leaving the late spermatids with highly condensed homogeneous chromatin. In the spermatid head, the conical acrosome is generally composed of an acrosomal vesicle which is formed by the coalescence of small proacrosomal vesicles within the cytoplasm, a subacrosomal space that situates between the acrosomal vesicle and nucleus, and an acrosomal rod which develops from a bunch of filamentous material within the subacrosomal space. Certain mitochondria move posteriorly towards the nucleus, thus constituting the spermatozoon midpiece. The flagellum, originated from the distal centriole, appears in the early spermiogenesis. Ultimately, mature spermatidium dissociates into numerous spermatozoa, which are subsequently released as a single cell from the coelom into the nephridia. The spermatozoon has a prominent head, containing an acrosome and nucleus, a short midpiece and a slender tail. When compared with other sipunculans or invertebrates with external fertilization, the spermiogenesis of P. esculenta, presumably, is closely associated with its biological adaptations for the reproductive strategy.

Re-evaluating the phylogeny of Sipuncula through transcriptomics

Sipunculans (also known as peanut worms) are an ancient group of exclusively marine worms with a global distribution and a fossil record that dates back to the Early Cambrian. The systematics of sipunculans, now considered a distinct subclade of Annelida, has been studied for decades using morphological and molecular characters, and has reached the limits of Sanger-based approaches. Here, we reevaluate their family-level phylogeny by comparative transcriptomic analysis of eight species representing all known families within Sipuncula. Two data matrices with alternative gene occupancy levels (large matrix with 675 genes and 62% missing data; reduced matrix with 141 genes and 23% missing data) were analysed using concatenation and gene-tree methods, yielding congruent results and resolving each internal node with maximum support. We thus corroborate prior phylogenetic work based on molecular data, resolve outstanding issues with respect to the familial relationships of Aspidosiphonidae, Antillesomatidae and Phascolosomatidae, and highlight the next area of focus for sipunculan systematics.

Isolation and characterization of microsatellite markers for Sipunculus nudus

Sipunculus nudus is an economically important marine fish species in China. In this study, a (GT)13-microsatellite-enriched library was constructed and 18 novel microsatellite loci were isolated and characterized. The number of alleles ranged from three to six. There were two loci pair in significant linkage disequilibrium and four loci significantly deviated from Hardy–Weinberg equilibrium. These microsatellite loci will be a powerful tool in population genetic studies of S. nudus, which will contribute to the conservation and management of the peanut worm.

A new genus and species of pinnotherid crab (Decapoda: Brachyura: Pinnotheridae: Pinnothereliinae) with a unique male abdominal appendage, and its symbiotic relationship with a sipunculan worm (Sipuncula) from Miami, Florida, U.S.A.

Abstract A new genus and species of pinnotherid crab, Laminapinnixa miamiensis, is described based on specimens mostly collected from sipunculan burrows in intertidal sand flats on Virginia Key, Miami, Florida. Males of this crab are characterized particularly by the presence of a conspicuous, broad, flattened, ventral abdominal appendage, herein referred to as the “abdominal plate” (AP). This structure has not previously been reported from brachyurans and occurs in males of all sizes (measured by carapace width, CW). Among 89 males and 87 females recovered, 50 crabs (24 males, 26 females) were associated with burrows of Sipunculus nudus Linnaeus, 1766. Hosts of most other specimens were not determined, but it is suggested that many were also likely associated with sipunculans. Eighteen sipunculan burrows had solitary crabs, whereas 15 had more than one; 14 of the 15 had heterosexual pairs. Carapace width (CW) and carapace length (CL) for males were 2.5 to 6.6 mm ( = 4.5 ± 1.0 mm) and 1.3 to 3.4 mm ( = 2....

Cold seep biogenic carbonate crust in the Levantine basin is inhabited by burrowing Phascolosoma aff. turnerae, a sipunculan worm hosting a distinctive microbiota

Biogenic calcium carbonate crusts represent a cryptic habitat that is often associated with hydrocarbon seeps. Most biological observations of these crusts concern the external surfaces and the fauna inhabiting their inner cavities are generally neglected. Exposed carbonates in areas of active seepage at the 1100-m-deep base of the Palmachim slumping feature in the Levantine basin are intensively burrowed by metazoans, especially by sipunculans (peanut worms), identified by genetic and morphological markers as a potentially novel Phascolosoma sp., closely related to Phascolosoma turnerae (Rice, 1985) and named here P. aff. turnerae. Bacterial 16S-based tag encoded FLX amplicon pyrosequencing (bTEFAP) was utilized to analyze the bacterial community associated with P. aff. turnerae. We compared the bacterial community structure in P. aff. turnerae to the bacterial community structure associated with the sediment–water interface in adjacent gas seeps and in biofilm covering the carbonate crust hosting the sipunculan. A distinctive microbiota, capable of chemosynthesis and sulfide detoxification, was found in association with P. aff. turnerae.

Sipuncula: an emerging model of spiralian development and evolution.

Sipuncula is an ancient clade of unsegmented marine worms that develop through a conserved pattern of unequal quartet spiral cleavage. They exhibit putative character modifications, including conspicuously large first-quartet micromeres and prototroch cells, postoral metatroch with exclusive locomotory function, paired retractor muscles and terminal organ system, and a U-shaped digestive architecture with left-right asymmetric development. Four developmental life history patterns are recognized, and they have evolved a unique metazoan larval type, the pelagosphera. When compared with other quartet spiral-cleaving models, sipunculan development is understudied, challenging and typically absent from evolutionary interpretations of spiralian larval and adult body plan diversity. If spiral cleavage is appropriately viewed as a flexible character complex, then understudied clades and characters should be investigated. We are pursuing sipunculan models for modern molecular, genetic and cellular research on evolution of spiralian development. Protocols for whole mount gene expression studies are established in four species. Molecular labeling and confocal imaging techniques are operative from embryogenesis through larval development. Next-generation sequencing of developmental transcriptomes has been completed for two species with highly contrasting life history patterns, Phascolion cryptum (direct development) and Nephasoma pellucidum (indirect planktotrophy). Looking forward, we will attempt intracellular lineage tracing and fate-mapping studies in a proposed model sipunculan, Themiste lageniformis. Importantly, with the unsegmented Sipuncula now repositioned within the segmented Annelida, sipunculan worms have become timely and appropriate models for investigating the potential for flexibility in spiralian development, including segmentation. We briefly review previous studies, and discuss new observations on the spiralian character complex within Sipuncula.

New records of Phascolosoma turnerae (Sipuncula: Phascolosomatidae) from the Balearic Basin, Mediterranean Sea

Specimens of the deep-water sipunculan worm Phascolosoma (Phascolosoma) turnerae were recently collected from the western part of the Mediterranean Sea. This species is characterized by hooks showing a peculiar anterior stout and long projection at their base. A key to all the Phascolosoma species found in the Mediterranean Sea is included.

Rapid Assessments of Metal Bioavailability in Marine Sediments Using Coelomic Fluid of Sipunculan Worms

A suitable test organism for assessing the bioavailability of sediment-bound metals should accumulate metals mainly from the sediment instead of other sources such as water. The deposit-feeding sipunculan worms, which indiscriminately ingest sediment particles and have a very low uptake rate of dissolved metals, appear to be such good candidates. The worms have additional advantage due to simple anatomy and are like little sacs full of liquid, that is, coelomic fluid, which can be easily collected for metal analysis after simple sample treatment. We measured the metal concentrations in a sipunculan worm, Phascolosoma arcuatum and in sediments collected from intertidal zones of Xiamen City, China. Significant correlations were found for the concentrations of chromium, nickel, copper, zinc, cadmium, and lead in sediments and their concentrations in both somatic tissue and coelomic fluid of the worms. Analyzing the metals in coelomic fluid led to similar results as the somatic-tissue metals for assessing the bioavailability of sediment-bound metals and the spatial pattern of sediment-bound metal contamination. Therefore, measuring coelomic-fluid metal concentrations can be used to provide a rapid assessment of metal bioavailability in marine sediments.

DNA barcoding reveals cryptic diversity in the peanut worm Sipunculus nudus

Peanut worm (Sipunculus nudus) is a cosmopolitan species mainly distributed in tropical and subtropical coastal waters. Analysis of the mitochondrial cytochrome c oxidase subunit I (COI) gene sequences among S.nudus from GenBank revealed high genetic variation (p-distance, 0.115-0.235; k2p, 0.128-0.297) and paraphyletic relationships. These indicated misidentification and/or cryptic diversity may be present in the genus Sipunculus. To understand the genetic diversity and to manage the recourse of S.nudus, we collected specimens from coastal waters of southern China and Taiwan. In the phylogenetic topology, specimens can be separated into four distinct clades; three of these clades (clade A, B and C) were only represented from this region (southern China and Taiwan), but the clade D grouped with individuals from Central America (Atlantic coast). Furthermore, individuals of clades A and D were collected at the same location, which does not support the hypothesis that this genetic break reflects contemporary geographical isolation. The four distinct clades observed among coastal waters of southern China and Taiwan indicated underestimated diversity. It is noteworthy that the cryptic diversity is vulnerable under high pressure of human activity.

Light from down under

Coral-algae symbiosis is a key feature of tropical corals and is highly dependent on the efficiency with which solar energy is attenuated by the coral. Scleractinian corals are among the most efficient light collectors in nature because of the modulation of the internal light field in the coral skeleton. Interestingly, coral skeleton particles composing the sandy bottoms in reef margins sustain these optical characteristics. In the present study, we examined two free-living coral species - Heterocyathus aequicostatus (Caryophyllidae) and Heteropsammia cochlea (Dendrophylliidae) - common on biogenic coarse carbonate sand of the Great Barrier Reef but absent from fine sand at the same depth. In coarse carbonate sand, light penetrates a few millimeters below the surface and propagates along horizontal distances of a few centimeters. In fine sand, almost all of the light is reflected back to the water column. For photosynthetic sand-dwelling organisms such as the studied species, with over one-third of their surface area facing the substrate, light flux to their underside may be beneficial. A correlation was found between the diameter of these corals and the distance that light may travel in the sand under the coral. Laboratory and field measurements show that the symbiotic algae on the underside of the corallites are photosynthetically active even when the coral is partially buried, implying sufficient light penetration. Other organisms in the study site, such as fungid corals and foraminiferans, with different morphologies, have different light-trapping strategies but are also photosynthesizing on their underside. The importance of the substrate type to the performance of the three main partners of the symbiosis (coral, endosymbiotic algae and a sipunculan worm) is highlighted, and is a striking example of co-evolution.

Peanut worms of the phylum Sipuncula from the Nha Trang Bay (South China Sea) with a key to species

Peanut worms of the phylum Sipuncula from the Nha Trang Bay (South China Sea) with a key to species

Biomagnification Profiles of Trace Elements through the Food Web of an Integrated Shrimp Mangrove Farm in Ba Ria Vung Tau, South Vietnam

Problem statement: Ba Ria Vung Tau (BRVT), a Vietnamese province with one of the fastest growing economies in the country, faces significant environmental challenges, including increased contamination of rivers and estuaries with urban and industrial wastes. Approach: Concentrations of 23 trace elements and stable isotope ratios (δ13C and δ15N) were analyzed in suspended particulate matter, one species of peanut worm, one species of octopus, six species of crustaceans and 13 species of fish collected from an integrated shrimp mangrove farm in the BRVT. Results: Concentrations of Cu, Zn, Se, Mo, Ag, Cd, Sb and Bi in octopus, Mn, Sr and Ba in crustaceans and Hg in fish were the highest among organisms analyzed. Using δ15N values to identify trophic positions, we found that Zn, Se and Hg biomagnified through the food web. The slope for Hg (0.048) was remarkably lower than those reported for other aquatic food webs. In contrast, the concentrations of most trace elements followed reverse trends (i.e., decreasing concentrations with increasing trophic level). Trace element concentrations we measured in organisms were within safe levels for human consumption according to criteria established by the Ministry of Agriculture, Fisheries and Food (MAFF) in the UK. However, concentrations of Cu in black tiger shrimps and octopus and Zn in Commerson's glassy fish were higher than the MAFF guidelines. Conclusion: The results of this study highlight the usefulness of δ13C and δ15N as a tool not only for elucidating the trophic position of biota, but also for tracing contaminants within food webs.

Peanut worms of the phylum Sipuncula from the Sea of Japan with a key to species

Sipunculan worms from the Russian waters of the Sea of Japan are still poorly investigated while they are much better known from the Japanese coast. The aim of this paper is to describe sipunculans from the Russian coast and from the deepest part of the Sea of Japan near the Primorye Province collected by SoJaBio expedition, and to provide keys for identification of sipunculan species from the Sea of Japan. At the Russian coast of the Sea of Japan only 8 valid species of sipunculans were found and identified: Golfingia margaritacea, G. vulgaris, Nephasoma capilleforme, N. wodjanizkii, Phascolion strombus, Thysanocardia nigra, Themiste hexadactyla (=T. pyroides), Phascolosoma agassizii. Taking into account 4 other valid species noted for this area, Nephasoma eremite, Thysanocardia catharinae, Themiste blanda and Phascolosoma scolops, which were not found, the sipunculan fauna of the Russian waters of the Sea of Japan now comprises 12 valid species. Nephasoma capilleforme and Nephasoma wodjanizkii are the first records for the North-West Pacific and the Sea of Japan. Species accounts include the most important taxonomic characters and specific biotope data. Accordingly, a key up to species level is provided. Totally, the fauna of the Sea of Japan is now estimated as having 31 valid species of sipunculans.

First record of the sipunculan worm Phascolion (Phascolion) caupo Hendrix, 1975 in the Mediterranean Sea

Specimens of the sipunculan worm Phascolion (Phascolion) caupo Hendrix, 1975 have been collected for the first time in the Mediterranean Sea, thus increasing the number of known sipunculan species of up to 36 in this area. They were encountered on soft bottoms from the coast of San Pedro del Pinatar (Western Mediterranean). Thirty specimens were collected at a depth ranging from 32.6 to 37.2 m, mainly in sandy substrata with high load of silt and clays. 80% of the individuals were found inhabiting empty shells of gastropods or empty tubes of serpulid polychaetes.