80 articles
Rhynchonella
Rhynchonella is an extinct rhynchonellide brachiopod genus erected by Fischer de Waldheim in 1809, type genus of Rhynchonellidae; many formerly included species have been reassigned to other genera.
Rotifer
Rotifers (phylum Rotifera, wheel animals) are microscopic aquatic animals with a ciliated corona and jawed mastax, over 2,200 species, mostly freshwater, used as fish-larvae feed and water-quality bioindicators.
Schizophoria
Schizophoria is an extinct genus of orthide brachiopods (family Schizophoriidae, named by King 1850, type species resupinatus) with biconvex punctate shells, cosmopolitan from Silurian-Devonian to late Paleozoic; not the fly section Schizophora.
Sipunculus nudus
Sipunculus nudus, the common peanut worm (Linnaeus, 1766), an unsegmented sipunculan marine worm of sandy tropical and subtropical coasts; farmed in China (~20,000 t/year), genome 1.75 Gb, phylogenetic placement debated.
Solenostomus snuffleupagus
Solenostomus snuffleupagus, the hairy ghost pipefish, is a species of ghost pipefish described in 2026 from the Coral Sea, distinguished by hair-like filaments and 36 vertebrae.
Spinocyrtia
Spinocyrtia is an extinct spiriferid brachiopod genus (family Spinocyrtiidae) named by Frederiks in 1916, type species Delthyris granulosa Conrad 1839, cosmopolitan in Middle Devonian seas (Eifelian-Givetian, 394.3-378.9 Ma).
Spirifer
Spirifer is an extinct Paleozoic brachiopod genus (Sowerby, 1818), type genus of Spiriferidae, order Spiriferida, with winged strophic shells, sulcus and fold, and spiral lophophore supports (spiralia).
Spiriferina
Spiriferina is an extinct genus of spire-bearing brachiopods in the order Spiriferinida, named by d'Orbigny in 1847 with type species Spirifer walcotti; its fossils range from the Silurian to the Jurassic across Asia, Europe, and the Americas.
Stringocephalus
Stringocephalus is an extinct genus of large, smooth, subglobular Devonian brachiopods (family Stringocephalidae), type species S. burtini, widespread in Eifelian-Givetian seas of Asia, Europe, Africa, and North America.
Strophomena
Strophomena is an extinct Ordovician (Caradoc–Ashgill) strophomenid brachiopod genus, type species Leptaena planumbona, a stationary epifaunal suspension feeder with a semicircular, resupinate shell, distinct from the mollusk Strophomenia.
Syringothyris
Syringothyris Winchell, 1863 is an extinct spire-bearing brachiopod genus (Syringothyrididae) with a diagnostic syrinx tube, ranging from the late Famennian to Serpukhovian, cosmopolitan, and a Lower Carboniferous index fossil.
Tardigrade
Tardigrades (water bears, phylum Tardigrada) are microscopic eight-legged animals famous for cryptobiosis, surviving radiation, vacuum, and spaceflight; studied via NASA's Cell Science-04 and the Dsup gene.
Tardigrades in space
Tardigrades in space: water bears (Richtersius coronifer, Milnesium tardigradum) surviving open-space vacuum, UV, and cosmic radiation, from the 2007 TARDIS FOTON-M3 experiment to ISS studies like Cell Science-04.
Tentaculites
Tentaculites, extinct conical Paleozoic fossils (class Tentaculita), Ordovician to Devonian, ringed calcareous shells; 2025 soft-tissue study links them to bryozoans, refuting molluscan affinity.
Timorebestia
Timorebestia koprii, Latin 'terror beast', a giant stem-group chaetognath predator worm up to 30 cm from the early Cambrian Sirius Passet Lagerstätte in North Greenland, described 2024, with ventral ganglion, fins, antennae, and gut contents proving predation.
Trichoplax
Trichoplax, type species Trichoplax adhaerens, is the tiny ciliated marine animal of the phylum Placozoa: a 2–3 mm flat plate with no neurons, muscles, or ECM, a ~98 Mb genome, and external digestion of algae.
Tullimonstrum
Tullimonstrum gregarium, the Tully Monster, Illinois' state fossil since 1989; a soft-bodied Pennsylvanian (~309 Ma) animal found only in the Mazon Creek beds, with a toothed proboscis and stalked eyes, whose classification remains debated.
Uncinulus
Uncinulus is an extinct Devonian rhynchonellid brachiopod genus (family Uncinulidae) established by Bayle in 1878, with globular, finely costate shells, cosmopolitan distribution, and a type species Hemithyris subwilsoni d'Orbigny.
Zeilleria
Zeilleria (Bayle, 1878) is an extinct terebratulid brachiopod genus, type of Zeilleriidae, with type species Z. quadrifida; it lived from the Middle Triassic to Early Cretaceous and is a common Jurassic Tethys fossil.
Zooplankton
Zooplankton: drifting aquatic animals unable to swim against currents, including copepods, krill, jellyfish, and larval stages (holoplankton vs meroplankton); key link in marine food webs and the ocean carbon cycle, strongly affected by climate warming.