Magical mysteries of marine sponges

Although they are often sidelined as the most ‘primitive’ of multicellular animals, sponges (Porifera) a key witness to early evolution complex life. As prolific filter feeders sea water, also important for marine ecology and could serve bioindicators ocean health pollution. Their unique abilities in biomineralisation, including formation glass spicules at ambient temperature, can inspire modern materials science. Michael Gross reports. The Aegean island Kalymnos has been home professional divers millennia. Due shortage agricultural land on volcanic ground, residents have always depended trade, successfully traded what found floor around their island, sponges. use natural cleaning other purposes is recorded literature Mediterranean antiquity going back Homer. ancient Greek Latin imported word ‘spongium’ from an unidentified but non-Indo-European language, whole idea exploiting these animals may cultural import well. tradition relied genera Spongia Hippospongia, which advantage being softer than don’t mineralised skeleton. In 19th century additional species abundantly Caribbean became popular. Natural were widely used until middle 20th when industrial production synthetic came dominate market, leaving work mainly tourist business. Today, interest many reasons: representatives one first forms life evolve, environmental health, sources bioactives inspiration enzymatically guided processing glass. Sponges without any differentiated tissues or organs. Like very embryo, only inner outer layer cells, quite lot pores water. Anything catch water digested by cells directly. It appears plausible assume this be deepest branch animal evolution, representing status before organs evolved. However, stages poorly represented fossil record, there debates over origins relation lineages. Specifically, some analyses molecular phylogeny appeared suggest that comb jellies (Ctenophora), although more anatomically, might represent earlier branching. group Gert Wörheide LMU Munich, Germany, then defence paper published journal end 2017, established inadequate data had produced artifactual results suggesting older (Curr. Biol. (2017) 27, 3864–3870). Further evidence evolutionary presence typical metabolites discovered ‘molecular fossils’ rocks oils Neoproterozoic (660–635 million years ago), 100 Cambrian explosion diversity, sponges, record. Gordon Love University California, Riverside, USA, originally steroid biomarker called 24-isopropylcholestane (24-ipc) sediments South Oman interpreted linking them today’s demosponges, largest diverse class phylum it objected certain algae able produce molecule. Recently, new biomarker, compound 26-methylstigmastane (26-mes), occurs together with 24-ipc structure currently known synthesised demosponges (Nat. Ecol. Evol. (2018) 2, 1709–1714). Even its metabolic precursors specific class. authors conclude findings “strongly hence prominent late environments least extending Cryogenian period.” earliest anatomical fossils assigned (but disputed some) Archaeocyatha (around 530 ago). They disappeared mid replaced rapidly diversifying groups we recognise appear Burgess Shale, instance (508 though went separate ways started evolving nervous systems, just much time evolve own complexities, elaborate mineral skeletons. Some intriguing examples recent deeper waters, such harp sponge (Chondrocladia lyra). This 2012 hooks exposed skeleton, trap small crustaceans. Once prey caught, releases membrane enzymes digest resorb nutrients. Another described recently demosponge Desmacella hyalina, thrives deep waters off coast British Columbia, Canada, where settles surface reefs formed After Canadian authorities designated area protected 2017 protect stretching across hundreds kilometres, Sally Leys Alberta robotic sampling device investigate living top reefs. already described, researchers noted different colour types. Genome revealed white type species, hyalina. While ecological importance reef itself crustaceans fish studied detail, interaction between forming live epibionts remains elucidated. principle depth unexplored, well large number waiting discovered. harvest sale soft throughout, hard skeleton made either calcium minerals silica, like latter material, hidden sometimes visible hexactinellids (glass sponges), particularly fascinated biologists material scientists. Humans producing since antiquity, process high temperatures, typically above 1400°C. So how primitive all delicate structures heat source? 1998 protein silicatein was confirmed catalyst silica deposition vitro. located core Tethya aurantium Igor Zlotnikov Technical Dresden, fibres scaffolding determines growth direction branching needles (Sci. Adv. 3, eaao2047). Structural functional hindered failure crystallise laboratory. Max Planck Institute Colloids Interfaces Potsdam, however, shown naturally crystalline state needles. his move he initiated effort solve crystal using material. Stefan Görlich attempted would tube normal x-ray crystallography. crystals smaller sensitive grown purpose, thus ended up severely damaged after single exposure. To obtain multiple angles required calculation electron density map determination structure, resort alternative technique combining crystals, serial collaboration Paul Scherrer Villigen, Switzerland, obtained 3,500 snapshots 90 computational methods fit calculate three-dimensional atomic resolution (Proc. Natl. Acad. Sci. USA (2020) 117, 31088–31093). largely agreement predictions based related proteins, turned out presumed active centre enzyme finding enzymatic function no longer needed once fibre surrounded glass, means mechanism cannot deduced structure. Thus, further challenges lie ahead recreate sponge’s factory laboratory decode secrets. Beyond biology, help scientists develop depositing microscopic context nanotechnology. actively pump thousands litres per day feeding, environment animals. led hypothesis suitable microparticle Many accumulate microparticles grains sand, role strengthening structures. Wörheide’s collected tissue samples 15 individuals five abundant growing shallow Indonesia incorporate foreign microparticles. Removal patch knife does not harm easily regenerate. On conducted histological microscopy Raman spectroscopy identify absorbed (Environ. Pollut. (2021) 268 A, 115851). wide range particles clearly anthropogenic origin, particulate cotton, titanium dioxide, plastic blue pigments. particle size detention location within none investigated preference accumulation types materials. pollution, indiscriminate sediment traps reflecting distribution surrounding them. widespread occurrence exposure conditions suggestions indicators quality chemical pollutants. More surprising, perhaps, retain DNA, enabling monitor biodiversity proxy. Stefano Mariani Salford Manchester, UK, colleagues reported journal, PCR vertebrate-specific primer sequences makes possible isolate DNA variety (2019) 29, R401–R402). majority 31 identified barcodes fishes, detected Weddell seals (Leptonychotes weddellii) chinstrap penguins (Pygoscelis antarcticus). suggested samplers studies, instead intrusive technical appliances considered submarines. “It’s quintessential environmentally friendly assessment tool,” said. If co-workers hadn’t selectively amplified vertebrate probably swamped microbial genomes because now regarded holobionts, host bacteria, archaea viruses. study Ute Hentschel Kiel Peter Schupp Oldenburg, both Wörheide, set broaden microbiome studies those colder climates, play bigger part symbionts previously appreciated (Front. Microbiol. 11, 716). constructed gene libraries microbiota sampled locations Pacific compared well-documented shallow-water demosponges. exclude possibility amplifying mentioned above, applied quantitative PCR. bacterial communities deep-water generally resemble except absence cyanobacteria understandable given specialise photosynthesis. A sponge-specific group, poribacteria, seemed underrepresented deep-sea Analysing seven hexactinellids, previous composition reported, gammaproteobacteria, fewer usually Only two showed similar Both family Nitrosopumilaceae (phylum Thaumarchaeota). hypothesise thaumarchaeotal ammonia oxidation precise holobiont Shallow-water aquaria subjected experimental changes conditions, temperature. coral Lendenfeldia chondrodes, Sergio Vargas Munich assessed responds rising temperatures (Microb. 81, 213–222. resilient towards expected change habitat. driven extinction human exploitation time. Similarly, concerns activities mining expand into threaten industrialise oceans (2015) 25, R1019–R1021). Swee-Cheng Lim Singapore Stelligeridae named Plenaster craigi (Syst. Biodivers. 15, 507–519). grows Clarion-Clipperton Zone, target polymetallic nodules, grapefruit-sized metal balls containing valuable resources, manganese, nickel, copper cobalt. Surveys encrust nodules. But even if directly removed harvested will risk floor. co-author Thomas Dahlgren Gothenburg, Sweden, pointed out, depths 4,000 metres depend amounts nutrients raining down, requiring larger species. “This vulnerable sand mud stirred nodules pumped collection barges surface,” Other industrial-scale trawling disrupt sea-floor age-old acknowledging exemplified collecting useful devices, endanger survival. benefiting areas, destroyed manage get know understand it.