Tubular Sponges Research Articles

Taking inspiration from the natural tubular sponge to enhance momentum exchange in marine environments

Coral reefs consist of various alive elements with specific biological functions. Tubular sponges, as the main coral reefs' constituents, have a marvelous mechanism. They receive nutrients by suctioning from the perforated body (Ostia) and pumping the un-digested materials through the water column from the top mouth (Osculum). This mechanism can be an inspiration for making a device to control or improve sediment/pollutant transport. In the current study, an attempt has been made to evaluate an inspired concept's effects on flow hydrodynamics. In this regard, OpenFOAM® V. 1812 (interFOAM solver) and image processing technique were deployed. The perforated finite-height cylinders (height to diameter ratio of 2.5) with various suction/pump discharges (i.e., J = 150, 300, 350, 400, 450, and 600 lit/h) were considered. The results indicated that increasing the outflow discharge (J ≥ 600 lit/h) could widen the wake by flapping the shear layer. In the vertical plane, the results showed that dipole vortices turned into quadrupole vortex. On the free surface, tip-vortices and counter-rotating vortex pairs (CRVP) generated saw-toothed vortices on two sides of the cylinder. Generating these unique vortices is proof of enhancing the momentum exchange through the water column.

Comparative Brain Morphology of Cleaning and Sponge-Dwelling Elacatinus Gobies.

Comparative studies of brain anatomy between closely related species have been very useful in demonstrating selective changes in brain structure. Within-species comparisons can be particularly useful for identifying changes in brain structure caused by contrasting environmental selection pressures. Here, we aimed to understand whether differences within and between species in habitat use and foraging behaviour influence brain morphology, on both ecological and evolutionary time scales. We used as a study model three species of the Elacatinus genus that differ in their habitat-foraging mode. The obligatory cleaning goby Elacatinus evelynae inhabits mainly corals and feeds mostly on ectoparasites removed from larger fish during cleaning interactions. In contrast, the obligatory sponge-dwelling goby Elacatinus chancei inhabits tubular sponges and feeds on microinvertebrates buried in the sponges' tissues. Finally, in the facultatively cleaning goby Elacatinus prochilos, individuals can adopt either phenotype, the cleaning or the sponge-dwelling habitat-foraging mode. By comparing the brains of the facultative goby phenotypes to the brains of the obligatory species we can test whether brain morphology is better predicted by phylogenetic relatedness or the habitat-foraging modes (cleaning × sponge dwelling). We found that E. prochilos brains from both types (cleaning and sponge dwelling) were highly similar to each other. Their brains were in general more similar to the brains of the most closely related species, E. evelynae (obligatory cleaning species), than to the brains of E. chancei (sponge-dwelling species). In contrast, we found significant brain structure differences between the cleaning species (E. evelynae and E. prochilos) and the sponge-dwelling species (E. chancei). These differences revealed independent changes in functionally correlated brain areas that might be ecologically adaptive. E. evelynae and E. prochilos had a relatively larger visual input processing brain axis and a relatively smaller lateral line input processing brain axis than E. chancei. The similar brain morphology of the two types of E. prochilos corroborates other studies showing that individuals of both types can be highly plastic in their social and foraging behaviours. Our results in the Elacatinus species suggest that morphological adaptations of the brain are likely to be found in specialists whereas species that are more flexible in their habitat may only show behavioural plasticity without showing anatomical differences.

Polymeric Carbon Nitride Tubular Sponges with Edge Functionalized Phosphonic Groups for Photocatalysis

Polymeric Carbon Nitride Tubular Sponges with Edge Functionalized Phosphonic Groups for Photocatalysis

Exploring implications of wave characteristics on the functionality of mimetic tubular sponges

Marine sponges influence the flow hydrodynamics by suction/pumping mechanism. They provide a recirculation flow and remove pollutants from their residence. Previous studies have validated the efficacy of mimetic sponges in improving momentum transfer in marine environments. This study endeavors to explore the impact of wave characteristics (i.e., wave height and period) on the momentum transfer near the mimetic sponges. Both physical and numerical simulations were undertaken to explore this phenomenon. Experimental results unveiled that the efficiency of the mimetic sponge is contingent upon some circumstances. When waves have a short period and height, the suction effects prevail. In such cases, orbital velocity tends to be in a negative direction, leading to suppressed fluctuating velocities and a reduction in turbulent kinetic energy throughout the water column. Thus, the penetration of the shear layer to the water column and occurrence of wake-street diminish. Conversely, an increase in wave height enhances the momentum exchange through the water column. Surface Line Integral Convolution and Three-Dimensional stream trace visualizations using OpenFOAM provide insights into the generation of spirals and vortices through the water column induced by mimetic sponges.

Inspiration of marine sponges to design a structure for managing the coastal hydrodynamics and protection: numerical study

Climate changes and sediment discharge within the oceans trigger many problems, such as coastline erosion and coral reef extinction hazards. Therefore, it is crucial to control wave hydrodynamics in the desired manner to protect marine environments. To prevent the promotion of sedimentation, nature has its response. The tubular sponge is a marvelous animal. It has a perforated body and sucks nutrition and water from these perforations; then, it pumps the undigested materials out from the top outlet. In the current study, an apparatus inspired by natural tubular sponges (synthetic sponges) was designed. The computational fluid dynamics derived from the Reynolds-averaged Navier-Stokes equations and image processing technique (surfaceLIC) was deployed to study how the synthetic sponge affects the wave hydrodynamics. The results revealed that the suction of the body and outflow shielding phenomenon of one sponge reduces the wave transmission by up to ≈7%. In addition, the swing motion of the jet by wave train and effluent cloud generation causes the shear on the sponge. Therefore, the momentum exchange enhances through the water column (≈46% increase of turbulent kinetic energy). It is similar to the swing behavior of flexible vegetation. Furthermore, the surfaceLIC result revealed that the effluent cloud shape changes to a pear shape, symmetric, stretched (transition), and asymmetric by increasing the pumping discharge to 600 L/h. Observing the chute–jet phenomenon by surfaceLIC also proved the diffraction and creation of a low-velocity zone in the shadow region, which is proof of a breaking wave due to the sponge’s suction/pumping and perforated body. Consequently, it can be concluded that a synthetic sponge can act as both rigid and flexible vegetation. The synthetic sponge is anticipated to mitigate sedimentation by creating unique vortices, circulating flow, and its body shape.

Testing the impact of Remotely Operated Vehicle (ROVs) camera angle on community metrics of temperate mesophotic organisms: A 3D model-based approach

While Remotely Operated Vehicle (ROV) technologies have rapidly increased our understanding of deeper water mesophotic ecosystems, there are some inherent problems in their use when estimating the abundance of sessile benthic organisms. Specifically, for rocky and coral reefs there has been recent debate about the importance of the angle of the ROV camera to the substrate, which is difficult to standardise, and how variation in this angle might impact abundance estimates and therefore our ability to detect change in mesophotic ecosystems. Here we simulated a series of 3D rocky temperate mesophotic communities based on real data with three different levels of habitat complexity (high, medium, and low). We ‘sampled’ these communities in a virtual space varying the angle of the camera to the substrate, to assess the influence of camera angle on percent cover estimates and overall benthic community composition. We found that increases in the ROV to substrate angle overestimated the percent cover (per degree of camera angle) of gorgonians (large: R2 = 0.16; small: R2 = 0.18), tubular sponges (R2 = 0.11), and ascidians (R2 = 0.05–0.13), and underestimated the abundance of Crustose Coraline Algae (R2 = 0.1, likely due to shading) in the most complex habitats. While we also found some significant differences in the overall benthic community and data dispersion for the more complex habitats, angle explained only a small amount of total variation (<6%) and significant dispersion was only found between 0- and 50-degree angles in high and medium complexity habitats. We conclude that while ROV to surface angle should be a consideration when sampling deep water reefs, its influence on standard measurements that we estimate with photography is likely to be low, and restricted to errors in the abundance of organisms with a high ratio of height to planar projection area (e.g., gorgonians).

Three-dimensional modeling of dilute sediment concentration around the synthetic sponge inspired by the tubular sponge mechanism

Marine tubular sponges use horizontal suction to receive the nutrients from the perforated body and pump the undigested materials from the top mouth. The idea of a synthetic sponge was inspired by the tubular one. It was introduced to manage the sediment-flow hydrodynamics for enhancing sediment transport in coral reefs and access channels. In the current study, synthetic sponge effects on the dilute sediment concentration were investigated numerically. The Mixture method based on Three-Fluids Modeling (TFM) was selected. The effects of pore area distributions (0–0.42) and jet flow discharges (0–7500 L/h) on the sediment concentration were evaluated. The surface Line Integral Convolution (surfaceLIC) was used as an image processing technique to assess the fluid hydrodynamics. The results indicate that the effects of perforation area distribution are more significant than suction/pumping discharges on the sediment concentration (94.87% vs. 5.13% contribution). So increasing the distribution of perforation areas can effectively reduce water turbidity (between 20% and 50%). The combination of the wide re-circulation zone, Counter Rotating Vortex Pair (CRVP), spiral flow, and dipole formation are the reasons for this. Therefore, the combination of vortices facilitates sediment transport due to the unique shape and mechanism of synthetic sponge.

Numerical Modeling of Sediment-flow around Obstacle Inspired by Marine Sponges: Considering Body Configurations

Coral reefs are exposed to extinction due to the sediment blocking through coral colonies. In this condition, there is no practical solution that originates from nature. Among all aquatic animals, marine tubular sponges have marvelous mechanisms. These natural creatures can inspire the design of a device for managing sediment-flow hydrodynamics. They suck flow from body perforation and pump water and undigested materials from the top outlet. Therefore, coinciding with receiving nutrients, the flow becomes circulated. This may help the momentum transfer through the coral colonies. In the current study, a synthetic sponge by motivating the tubular sponges was designed. Synthetic sponges’ suction/pumping discharge was constant at 150 L/h. They have a body diameter of 8 and 15 cm and a height of 20 cm. The perforation area distribution changes to understand how it may influence sediment-flow hydrodynamics. The numerical modeling based on Reynolds Averaged Navier Stokes (RANS) equations and image processing technique (surface LIC) were deployed to determine the vortical flow patterns. Results confirmed that choosing the best body perforation configuration and area distribution can generate the dipole vortex. In this condition, a tornado combines with dipole and erodes the sediments to ≈ 30% near the bed. Moreover, the sediment concentration reduces to ≈ 20% in the water column at X/D =1. In this condition, it can be observed that the emergence of specific vorticities and re-circulations develops the suspension of particles. Therefore, the synthetic sponge with precise design can be practical for enhancing the momentum transferring and preventing pollutant blockage among coral colonies.

Spatial Ecology of the Association between Demosponges and Nemalecium lighti at Bonaire, Dutch Caribbean

Coral reefs are known to be among the most biodiverse marine ecosystems and one of the richest in terms of associations and species interactions, especially those involving invertebrates such as corals and sponges. Despite that, our knowledge about cryptic fauna and their ecological role remains remarkably scarce. This study aimed to address this gap by defining for the first time the spatial ecology of the association between the epibiont hydrozoan Nemalecium lighti and the Porifera community of shallow coral reef systems at Bonaire. In particular, the host range, prevalence, and distribution of the association were examined in relation to different sites, depths, and dimensions of the sponge hosts. We report Nemalecium lighti to be in association with 9 out of 16 genera of sponges encountered and 15 out of 16 of the dive sites examined. The prevalence of the hydroid–sponge association in Bonaire reef was 6.55%, with a maximum value of over 30%. This hydrozoan has been found to be a generalist symbiont, displaying a strong preference for sponges of the genus Aplysina, with no significant preference in relation to depth. On the contrary, the size of the host appeared to influence the prevalence of association, with large tubular sponges found to be the preferred host. Although further studies are needed to better understand the biological and ecological reason for these results, this study improved our knowledge of Bonaire’s coral reef cryptofauna diversity and its interspecific associations.

Stratigraphic model of a Middle-Late Jurassic carbonate system (Mozduran Ridge, Kopet Dagh area, NE Iran)

Lithostratigraphy and biostratigraphy of Middle to Upper Jurassic carbonate platforms of the Eastern Kopet Dagh (EKD), northeastern Iran were assessed. Up to 3000 m of sedimentological logs located along ten stratigraphic sections were investigated. At least five types of carbonate production systems were identified in the study area: (1) a mud-dominated platform carbonate topped by (2) an off-platform carbonate grain-production system, (3) a grain-reworking system deposited within basinal settings (gravity-driven reworking), (4) mounds built by tubular sponges and corals, and (5) prograding oolitic wedges. The first carbonate production system (Callovian‒early Oxfordian) yields platy and solitary corals, together with stromatactis-like structures. The second carbonate production system is represented by upper Oxfordian off-platform grainstones. These two carbonate production systems comprise the Khaneh Zou Fm. The third system is characterised by oncoids, originating from the carbonate platforms. These oncoids, together with bioclasts, were transported into the Kimmeridgian hemipelagic succession of the Chaman Bid Fm. The last two carbonate production systems are common in the Mozduran Fm. Tithonian tubular sponges-corals mounds, and their related dismantling products constitute a major characteristic system of the Mozduran Fm. Shallowing-upward prograding clinoforms are a second characteristic system of the Mozduran Fm., whereby ooids, generated under shallow-water conditions, were shed downslope to form interbeds within basinal mudstones. Our findings suggest that the combination of 2nd order eustatic sea-level changes with hydrodynamic processes as well as rift-inherited morphologies and climatic changes controlled the development and lateral facies evolution of the Middle to Upper Jurassic carbonate platforms. The description of these carbonate systems and of their morphology, together with stratigraphic interpretations may lead to exploration of complex structural-stratigraphic traps, thereby highlighting new potential hydrocarbon reservoirs in the EKD.

Bottom trawling on a carbonate shelf: Do we get what we see?

Bottom trawling is a common fisheries method and also a widespread scientific sampling method for benthic and demersal species. Selectivity and catchability are usually estimated using different meshes and studies with alternative methods are rare. In this study, to improve the estimation of trawl selectivity, we compare bottom trawl catches and recordings made by a camera fitted on the top of the net. Scientific trawling was conducted along the Northeast Brazilian shelf, a typical carbonate shelf with presence of sponges, coralline bottoms and a high water visibility. In total, 23 taxa (19 species and four genera) were identified in the videos and 30 taxa (25 species and five genera) in the trawls, indicating a higher potential of trawling to record species richness. Overall, no significant differences were observed in the assemblage structure identified by trawling and underwater footages. However, divergences were observed in fish catchability between trawls and videos. Net sampling was more selective for fish with low swimming capacity, while species with shelter and fast swimming capacity seemed to be underestimated. Furthermore, underwater footages allowed for an assessment of the trawling impacts on erect sponges with the observation of the damage on large branching and tubular sponges. The vulnerability of those habitats that concentrate higher fish diversity to mechanical impact raise the need for creation of preventive measures to protect these sensitive areas from commercial fishing operations. The use of less destructive methods is an important survey alternative under special conditions, particularly in conservation areas. In this study the videos could not be used as a complete alternative for the trawls, which presented higher efficiency, however, videos had shown to be a useful complement. Possibly, the speed and height determined by the trawling operation affected the performance of video sampling, being performed in suboptimal conditions. Using dedicated video sampling, such as towed video, could significantly improve its efficiency and compensate the disadvantages observed from the videos.

Virtually Wall-Less Tubular Sponges as Compartmentalized Reaction Containers.

Sponges are open cellular materials with numerous interesting features. However, the potential of compartmentalized sponges has not been explored although many new properties and applications could be envisioned. We found that compartmentalized fibrous ultraporous polymer sponges with superhydrophobic surfaces could be designed as virtually wall-less reaction containers. With this, for example, the efficient removal of CO2 from water and the controlled mineralization of calcium carbonate are possible. The high porosity (>99%) and superhydrophobicity make these sponges ideal candidates to hold alkanolamine solution for absorbing CO2 and exchange gas through the walls of the sponges. The tubular sponge exhibits a much higher evaporation rate than a glass tube with the same diameter due to the much larger contact area between water and air. Therefore, the spongy reaction container also possesses a much faster adsorption rate, smaller equilibration time and higher efficiency for CO2 adsorption than the glass tube container. In addition, these tubular sponges are also utilized to precipitate calcium carbonate by ammonium carbonate decomposition, which can control the deposition rates and products by tailoring the porosity and surface chemistry in the future. These new sponges provide an ideal basis for numerous new applications, for example, as breathable pipe lines for gas-liquid exchange, slag slurry carbonization, humidifier, and blood enricher.

Amended definitions for Aplysinidae and Aplysina (Porifera, Demospongiae, Verongiida): on three new species from a remarkable population in the Gulf of California.

Verongiid sponges inhabiting the La Paz region, Gulf of California are described herein as new species. Although morphological evidence was sufficient to determine the identity between species, we have confirmed their uniqueness and relationships with molecular (CO1 and ITS1 and 2), and ecological studies. An amended definition of family Aplysinidae and genus Aplysina is presented to highlight a novel skeletal trait for the latter, clearly described herein as a complex of dendritic fibers sustained by anastomosed fibers deep in the choanosome. This novel fiber arrangement combination is a constant trait of Aplysina encarnacionae sp. nov. and A. airapii sp. nov., which otherwise conform to our current concept of Aplysina. The former species has a long tubular morphology, reddish purple color, with the longest dendritic fibers; while A. airapii sp. nov. is a short tubular sponge, yellow with reddish tints, and smaller choanosomal dendritic fibers that depart from a uniplanar anastomosed skeleton. A third species, A. sinuscaliforniensis sp. nov., is characterized by a completely anastomosed skeleton, massive habit with short tubes superimposed one over the other, sympatric with the other new species. Comparisons with Suberea azteca verified that the same novel skeletal architecture described here occurs in the latter, while Aiolochroia thiona examined as well, proved to bear an anastomosed skeleton only, besides sharing more features with Aplysina than with any other genera in Verongiida. Moreover, molecular sequencing recovered "S." azteca nested in the Aplysina clade, prompting us to reallocate it in Aplysina, as originally proposed. The new species described herein are probably endemics within the Gulf of California since they have not been recorded elsewhere along the Mexican Pacific coast.

Rediscovering Chemical Gardens: Self-Assembling Cytocompatible Protein-Intercalated Silicate-Phosphate Sponge-Mimetic Tubules.

The classic chemical garden experiment is reconstructed to produce protein-intercalated silicate-phosphate tubules that resemble tubular sponges. The constructs were synthesized by seeding calcium chloride into a solution of sodium silicate-potassium phosphate and gelatin. Sponge-mimetic tubules were fabricated with varying percentages of gelatin (0-15% w/v), in diameters ranging from 200 μm to 2 mm, characterized morphologically and compositionally, functionalized with biomolecules for cell adhesion, and evaluated for cytocompatibility. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy analysis (EDS) experiments showed that the external surface of the tubules was relatively more amorphous in texture and carbon/protein-rich in comparison to the interior surface. Transmission electron microscopy (TEM) images indicate a network composed of gelatin incorporated into the inorganic scaffold. The presence of gelatin in the constructs was confirmed by infrared spectroscopy. Powder X-ray diffraction (XRD) was used to identify inorganic crystalline phases in the scaffolds that are mainly composed of Ca(OH)2, NaCl, and Ca2SiO4 along with a band corresponding to amorphous gelatin. Bioconjugation and coating protocols were developed to program the scaffolds with cues for cell adhesion, and the resulting constructs were employed for 3D cell culture of marine (Pyrocystis lunula) and mammalian (HeLa and H9C2) cell lines. The cytocompatibility of the constructs was demonstrated by live cell assays. We have successfully shown that these biomimetic materials can indeed support life; they serve as scaffolds that facilitate the attachment and assembly of individual cells to form multicellular entities, thereby revisiting the 350-year-old effort to link chemical gardens with the origins of life. Hybrid chemical garden biomaterials are programmable, readily fabricated and could be employed in tissue engineering, biomolecular materials development, 3D mammalian cell culture and by researchers investigating the origins of multicellular life.

First record of the dottyback Manonichthys alleni (Teleostei: Perciformes: Pseudochromidae) from the Philippines

Several specimens of the pseudochromid Manonichthys alleni , with total length ranging from 45 to 60 mm, were observed at depths of 19–28 m in a coral reef in the Davao Gulf in the southern Philippines. Each specimen lived within a separate colony of the tubular sponge Callyspongia aerizusa . This constitutes the first record in the Philippine archipelago of a dottyback so far only known from Indonesian and Malaysian waters.

Retention efficiencies of the coral reef sponges Aplysina lacunosa, Callyspongia vaginalis and Niphates digitalis determined by Coulter counter and plate culture analysis

Sponges are the dominant organisms on many coral reefs and through feeding they may greatly reduce the concentration of suspended food particles. Retention efficiencies of the tubular sponges Aplysina lacunosa, Callyspongia vaginalis and Niphates digitalis were examined on a coral reef located in the Florida Keys. Replicate ambient and exhalant water samples were collected in situ from individuals of each species and analysed using two methods. Retention efficiencies of suspended particles (0.75–18 µm) examined using Coulter counter analysis were similar among the three sponge species, averaging 86%. For all sponges, particle retention decreased as particle size increased from 0.7 to 18 µm. Water samples plated on to Marine Agar produced 54 microbial types. Retention efficiencies of culturable microbes were similar among the three species, averaging 82%. This study suggests that the coral reef sponges Aplysina lacunosa, Callyspongia vaginalis and Niphates digitalis play an important role in the transfer of energy between the pelagic and benthic environments.

Evidence for morphology-induced sediment settlement prevention on the tubular sponge Haliclona urceolus

Several mechanisms are known to assist the survival of sponges in highly sedimented environments. This study considers the potential of sponge morphology and the positioning of exhalant water jets (through the osculum) in the adaptation of Haliclona urceolus to highly sedimented habitats. This sponge is cylindrical with an apical osculum, which is common in sedimented subtidal habitats at Lough Hyne Marine Nature Reserve, Cork, Ireland. Fifteen sponges were collected, preserved (killed with the structure and morphology maintained) and then replaced in a high sediment environment next to a living specimen (at 24 m). After 5 days, the sediment settled on both living and preserved sponges was collected and dried. No sediment was collected from living sponges, while preserved specimens had considerable amounts of settled sediment on their surfaces. The amount of sediment collected on these preserved specimens was significantly linearly correlated with sponge dry weight, maximum diameter and oscula width (R2>0.70, P<0.001, df=14). Observations of flow direction (using coloured dye) through H. urceolus showed that water is drawn into the sponge on its underside and exits via a large vertically pointing osculum. Sponge morphologies (shape) have often been considered as a means of passive adaptation to a number of different environmental parameters with oscula position enabling entrained flow through the sponge in high flow conditions. However, this study shows how the combination of sponge morphology (tubular shape) and positioning of the osculum may enable H. urceolus to survive in highly sedimented environments. Similar mechanisms may also aid the survival of some deep-water sponge species with similar morphologies.

Sponge-dwelling Fishes of Northeastern Brazil

In this first attempt to survey the Brazilian sponge-dwelling fishes we present a list of collected fishes, with notes on their distribution, abundance and habitat preferences. Risor ruber, an obligate sponge-dwelling goby, and Scorpaenodes tredecimspinosus , never before collected in association with sponges, are recorded for the first time in the western South Atlantic based on collections made in localities on the northeastern Brazilian coast. Previous work on Risor ruber indicated that it preferred massive sponges, but in our study the majority of the specimens were found in the lumen of tubular sponges, Aplysina lacunosa, together with other fishes and invertebrates, mostly crustaceans. Elacatinus figaro, originally described as a cleaner goby, is also a sponge-dweller that occurs in waters much deeper than previously thought. The sponge community off northeastern Brazil represents the only shelter for several species of fishes in a desert of rubble and flat rocky bottoms, perhaps functioning as habitat ‘oases’. We also found four Brazilian endemic species of fishes associated with sponges in depths greater than 50 m, which contradicts a previous hypothesis suggesting that endemic fishes in Brazilian coastal waters are restricted to depths less than 50 m.

Early Cambrian sponges from Vermont and Pennsylvania, the only ones described from North America

Early Cambrian Leptomitus zitteli Walcott, 1886, is a tubular, double-walled, demo-sponge from the Parker Slate of Vermont and is one of the few intact sponges of that age known. It occurs with skeletal fragments of ?Protospongia hicksi Hinde, 1887. Hazelia walcotti (Resser and Howell, 1938) is a thin-walled, tubular sponge with crudely clustered oxeas in a thatched skeleton. It is known from the Kinzers Formation of Pennsylvania. Early occurrences of Leptomitus and Hazelia indicate that at least these two lineages had diverged by the latter part of the Early Cambrian. The impression described as Leptomitus minor by Resser and Howell (1938) lacks spicules and is not a sponge.

III.—Notes on Fossil Sponges

III. Pictet converted D’Orbigny's families into tribes, and introduced some additional genera created by Giebel King, etc.; and, except in the description of new genera and species by Reuss, Roemer, Salter, Eichwald and others, the subject remained very much where D’Orbigny left it until M. de Fromentelle proposed a new arrangement, based upon what he terms the “organs which serve for the nutrition of the sponge,”—viz., the tubule, oscules, pores, etc. Like D’Orbigny, he divides the sponges into two orders: 1st, the Spongitaria, which comprises only recent genera; and, 2nd, the Spongitaria, which contains all the fossil genera, with the exception of the doubtful group, the Clionidæ. The second order is further divided into three sub-orders: 1, those sponges which have one or more tubules (the Spongitaria tubulosa); 2, those that have oscules, but no tubule (Spongitaria osculata); and 3, those that have neither tubule nor oscules (Spongitaria porosa). Each of these suborders is further divided thus: the tubular sponges into those in which the tubule is solitary, and those in which it is grouped, and also into those with oscules and those without oscules. The oscular sponges are similarly subdivided, according to form, disposition of the oscules, and presence or absence of an epitheca. Lastly, the porous sponges are divided into those that are more or less regularly cup-shaped, and those that assume some other form.