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•Traditional ideas of sponge growth forms were reviewed in a purely functional context.•Functional sponge morphologies reflect prevailing ambient conditions.•Sponge morphological ...strategies respond most strongly to flow and sedimentation.•The proposed scheme can be used in addition to or instead of taxonomy.•The scheme suits environmental assessment, monitoring and citizen science.
The need to study sponge communities in comparatively inaccessible habitats led to a sponge classification system that relies on the strictly functional interpretation of traditional sponge morphologies. The aim is to deliver a standardised approach that can optionally be based on imagery and can be applied across all oceans and to any water depth. The system is designed to recognise community-level changes across time and space. The functional context allows a basic interpretation of environmental conditions and may thereby inform on the reasons for observed differences in prevailing morphologies. In terms of growth form sponges appear to respond most strongly to the flow regime and to sediments. Strong turbulent flow will favour low-relief, morphologically simple sponges that are often structurally reinforced and well attached, such as crusts and simple-massive forms. Laminar flow selects for two-dimensionally erect, vertically flattened, usually flexible sponges that are aligned broadside to the current, inhalant openings (ostiae) pointing upstream, and exhalant openings downstream (oscula). Flow strength is generally inversely related to number of erect sponges, to body height (except in globular sponges), oscular diameter, branch number and branch complexity. Where flow conditions reduce or limit access to water exchange and nutrients, sponges tend to separate in- and exhalants in cup-like forms, reach into the water column as erect and even stalked forms, and in cases of extreme nutrient limitation the community will consist predominantly of carnivorous sponges. Globular and fistular sponges are usually abundant where the substrate is dominated by sediments, and where sediment deposition or movement is high. Fine sediments will often exclude sponges with much horizontal surface area. Based on these insights, the proposed scheme uses four basic morphologies: functional 1 – crusts, 2 – massives, 3 – cups and 4 – erect sponges. These are further divided into sponges that function as 1 – true crusts, endolithic-bioeroding, and creeping sponges, 2 – simple-massive, globular massive, composite-massive, and fistular sponges, 3 – cups, tubes, and barrels, and 4 – one-dimensionally, two-dimensionally and three-dimensionally erect forms, stalked, and carnivorous sponges.
Biological erosion is a key process for the recycling of carbonate and the formation of calcareous sediments in the oceans. Experimental studies showed that bioerosion is subject to distinct temporal ...variability, but previous long-term studies were restricted to tropical waters. Here, we present results from a 14-year bioerosion experiment that was carried out along the rocky limestone coast of the island of Rhodes, Greece, in the Eastern Mediterranean Sea, in order to monitor the pace at which bioerosion affects carbonate substrate and the sequence of colonisation by bioeroding organisms. Internal macrobioerosion was visualised and quantified by micro-computed tomography and computer-algorithm-based segmentation procedures. Analysis of internal macrobioerosion traces revealed a dominance of bioeroding sponges producing eight types of characteristic Entobia cavity networks, which were matched to five different clionaid sponges by spicule identification in extracted tissue. The morphology of the entobians strongly varied depending on the species of the producing sponge, its ontogenetic stage, available space, and competition by other bioeroders. An early community developed during the first 5 years of exposure with initially very low macrobioerosion rates and was followed by an intermediate stage when sponges formed large and more diverse entobians and bioerosion rates increased. After 14 years, 30 % of the block volumes were occupied by boring sponges, yielding maximum bioerosion rates of 900 g m−2 yr−1. A high spatial variability in macrobioerosion prohibited clear conclusions about the onset of macrobioerosion equilibrium conditions. This highlights the necessity of even longer experimental exposures and higher replication at various factor levels in order to better understand and quantify temporal patterns of macrobioerosion in marine carbonate environments.
Being sessile filter feeders, sponges may be disadvantaged by sediments in many ways, e.g. through clogging and burial. However, in order to correctly recognize negative effects of sediments in the ...field, natural relationships of sponge taxa adapted to a life with sediments need to be understood. The present publication reviews available literature and provides observations on natural and beneficial interactions of sponges with sediments, distinguishing several strategies: (1) Saving energy through sediment incorporation, reducing or replacing spicule production commonly occurs in keratose, verongimorph, tethyid and poecilosclerid sponges, which often received scientific names referring to sediments. (2) Forming sediment crusts externally or embedded in surface tissues reinforces outer layers, provides shade, and for external crusts camouflage and shelter from spongivory and desiccation. External crusts often occur in the tethyids and axinellids, while surface armour is most common in keratose sponges. (3) Anchoring in soft sediments provides a selective advantage for space colonization. This is mainly achieved in the hexactinellid, polymastiid and spirophorine sponges by using spicules (predominantly in deeper water), commonly in endopsammic sponges by rootlets, basal agglutination and basal incorporation of particles, and in various groups by attachment to buried materials (shallow water). (4) Living at least partially embedded in sediments (psammobiosis) appears to be best developed in Oceanapia spp. and bioeroding sponges, generates shelter from various external conditions and reduces the risk of spongivory. Typical morphological characters of sediment-adapted sponges are thus sediment skeletons and surface crusts (reinforcement), stalks and fistules (elevation above sediments), spicule tufts and root-systems (anchoring).
During a multi-agency Australian Government initiative sponges were sampled at three areas from Carnarvon Shelf, NW Australia. Sponges were identified to lowest possible level, largely as ...morphospecies (84%). A searchable and interactive taxonomic catalogue was created and is publicly accessible through the Ningaloo Atlas collated by the Australian Institute for Marine Science. The sponge gardens on Carnarvon Shelf are patchily distributed but highly diverse and occasionally extremely dense. We examined 754 specimens and distinguished 261 species belonging to 112 genera. Species accumulation curves indicate that this species number does not represent local sponge biodiversity, which is projected to reach up to 840 species with additional sampling. Many observed species appear to be new to science, 81% occurred only at one of the three areas, about 56% were singletons, and 76% had a wet weight of ≤500 g. Detailed spatial analyses were difficult due to sampling design, but general trends could be detected. The northern areas, where the Australian continental shelf is narrowest, favour sponges with a higher content of inorganic skeleton and growth forms able to withstand the strong tidal currents and exposure typical for this area. Sponges were most abundant at the shelf edge, where massive forms dominated. While the central and northern areas are protected by zoning regulations, the southern area had the highest species diversity, the largest individuals and the densest distributions, suggesting additional conservation measures may be required. Western Australia is clearly an important, but under-studied bioregion for sponges, and future research foci are proposed.
After observing a fight between two snowflake eels in southern Taiwan, we had difficulties locating scientific information on eel–eel aggressive behaviour and looked further afield. We collected and ...scored 34 videos posted on social media, to provide more insight into antagonistic behaviours in eels. The videos showed 12 different species of moray eels involved in aggressive interactions, with the genus
Gymnothorax
contributing to ~ 71% and
Echidna
contributing to 24% of the observed occurrences. 82% of the videos documented antagonistic interactions between conspecifics. The fights involved “knotting”, when opponents curl around each other and shove with their bodies, and some biting. Overall, the incidence of injury and death of losers, as well as injury of winners, was higher in smaller-bodied opponents. Conspecific encounters elicited the greatest intensity of aggressive behaviour, which we interpreted as rivalry due to dominance hierarchies and territoriality. This normally included a visible resource the opponents fought over (a den, a food item, a mate). Same-species fights started after gaping mouths at each other, with individuals being roughly equal in size. Conspecific opponents were often injured, but never killed. Available videos with fights between different species included predatory attacks and defensive reactions. Except for one case, interspecific encounters often ended with one eel being killed and eaten, with the winner being a fish-eating
Gymnothorax
species. Pre-fight, the killer was observed displaying food searching behaviour by checking holes. Both conspecific and interspecific fights frequently incurred deep, V-shaped wounds that were not apparently life threatening. Old V-shaped scars occurred on the bodies of some eels. Such scars could be used in research further investigating aggressive behaviour in moray eels.
The suprachiasmatic nucleus (SCN) circadian clock is critical for optimising daily cycles in mammalian physiology and behaviour. The roles of the various SCN cell types in communicating timing ...information to downstream physiological systems remain incompletely understood, however. In particular, while vasoactive intestinal polypeptide (VIP) signalling is essential for SCN function and whole animal circadian rhythmicity, the specific contributions of VIP cell output to physiological control remains uncertain. Here we reveal a key role for SCN VIP cells in central clock output. Using multielectrode recording and optogenetic manipulations, we show that VIP neurons provide coordinated daily waves of GABAergic input to target cells across the paraventricular hypothalamus and ventral thalamus, supressing their activity during the mid to late day. Using chemogenetic manipulation, we further demonstrate specific roles for this circuitry in the daily control of heart rate and corticosterone secretion, collectively establishing SCN VIP cells as influential regulators of physiological timing.
Twilight is characterised by changes in both quantity ("irradiance") and quality ("colour") of light. Animals use the variation in irradiance to adjust their internal circadian clocks, aligning their ...behaviour and physiology with the solar cycle. However, it is currently unknown whether changes in colour also contribute to this entrainment process. Using environmental measurements, we show here that mammalian blue-yellow colour discrimination provides a more reliable method of tracking twilight progression than simply measuring irradiance. We next use electrophysiological recordings to demonstrate that neurons in the mouse suprachiasmatic circadian clock display the cone-dependent spectral opponency required to make use of this information. Thus, our data show that some clock neurons are highly sensitive to changes in spectral composition occurring over twilight and that this input dictates their response to changes in irradiance. Finally, using mice housed under photoperiods with simulated dawn/dusk transitions, we confirm that spectral changes occurring during twilight are required for appropriate circadian alignment under natural conditions. Together, these data reveal a new sensory mechanism for telling time of day that would be available to any mammalian species capable of chromatic vision.
NMDA receptors (NMDARs) play an important role in neural plasticity including long-term potentiation and long-term depression, which are likely to explain their importance for learning and memory. ...Cognitive decline is a major problem facing an ageing human population, so much so that its reversal has become an important goal for scientific research and pharmaceutical development. Enhancement of NMDAR function is a core strategy toward this goal. In this review we indicate some of the major ways of potentiating NMDAR function by both direct and indirect modulation. There is good evidence that both positive and negative modulation can enhance function suggesting that a subtle approach correcting imbalances in particular clinical situations will be required. Excessive activation and the resultant deleterious effects will need to be carefully avoided. Finally we describe some novel positive allosteric modulators of NMDARs, with some subunit selectivity, and show initial evidence of their ability to affect NMDAR mediated events.
This article is part of a Special Issue entitled ‘Cognitive Enhancers’.
► Cognitive decline is a major problem facing an ageing human population. ► NMDA receptors play an important role in neural plasticity and learning and memory. ► Excessive activation of NMDA receptors results in deleterious effects. ► Subtle fine-tuning of NMDAR function is needed for control of cognitive decline. ► Positive allosteric modulators of NMDARs can affect NMDAR mediated events.
Bosentan is an endothelin receptor antagonist (ERA) prescribed for patients with pulmonary arterial hypertension (PAH). The oral delivery of bosentan possesses several drawbacks such as low ...bioavailability (about 50%), short duration of action, frequent administration, hepatotoxicity and systemic hypotension. The pulmonary administration would circumvent the pre-systemic metabolism thus improving the bioavailability and avoids the systemic adverse effects of oral bosentan. However, the short duration of action and the frequent administration are the major drawbacks of inhalation therapy. Thus, the aim of this work is to explore the potential of respirable controlled release polymeric colloid (RCRPC) for effective, safe and sustained pulmonary delivery of bosentan. Central composite design was adopted to study the influence of formulation and process variables on nanoparticles properties. The particle size, polydispersity index (PDI), entrapment efficiency (EE) and in vitro bosentan released were selected as dependent variables. The optimized RCRPC showed particle size of 420 nm, PDI of 0.39, EE of 60.5% and sustained release pattern where only 31.0% was released after 16 h. The in vitro nebulization of RCRPC indicated that PLGA nanoparticles could be incorporated into respirable nebulized droplets better than drug solution. Pharmacokinetics and histopathological examination were determined after intratracheal administration of the developed RCRPC to male albino rats compared to the oral bosentan suspension. Results revealed the great improvement of bioavailability (12.71 folds) and sustained vasodilation effect on the pulmonary blood vessels (more than 12 h). Bosentan-loaded RCRPC administered via the pulmonary route may therefore constitute an advance in the management of PAH.
Perceived changes in the culture of sponge science and sponge conferences served as motivation for an evaluation of the sponge science community and research, over time and at present. Observed ...changes included a decrease in proceedings publications on sponge fossils and freshwater sponges, sponges from temperate environments, review papers and data syntheses, frequency of aquarium studies, and number of species investigated per publication. Publications on recent sponges, hexactinellids, calcareans, marine, Indo‐Pacific and warm‐water sponges increased, as well as the number of authors per publication and the proportion of field studies. Studies at the level of specimens and ultrastructure were gradually replaced by molecular approaches, but studies at the community level remained stable. The five sub‐disciplines morphology/taxonomy, phylogeny/evolution, physiology, ecology and faunistics also retained about equal proportions over time. Conference publications related to taxonomy, phylogeny and biodiversity prevailed, whereas those on management and conservation were rare, possibly because studies on sponge recovery, survival and mortality were also scarce. The community of sponge scientists has grown and become more diverse over time, presently representing 72 nations. The gender distribution evened out since the first sponge conference and presently favours women at early and men at late career stages. Although stated research interests are generally dominated by physiology and ecology, taxonomy and evolution are favoured after retirement. Sponge science has become more dynamic, but maybe also more competitive and less inclusive. We now face the dual challenge of safeguarding against the loss of some sub‐disciplines, and fostering the collaborative, helpful culture characteristic of sponge science.
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