Intertidal
Guides
Aegialites californicus
Aegialites californicus is a flightless intertidal beetle in the family Salpingidae. It inhabits the supralittoral zone of rocky shores along the northern Pacific coast, from California to Alaska and across to northern Japan and Kamchatka. The species possesses specialized morphological adaptations for its challenging habitat, including widely separated coxae, long tarsi, and large claws. Its complete mitochondrial genome has been sequenced, representing the first such data for the genus Aegialites.
Aleochara sulcicollis
A rove beetle species in the family Staphylinidae with a documented parasitoid life history involving kelp flies. Larvae develop as parasitoids of intertidal kelp flies, specifically Fucellia rufitibia, with adults likely active in coastal habitats where macroalgae and host flies occur. The species has been recorded across a broad geographic range spanning North, Central, and South America.
Amblopusa
Amblopusa is a genus of intertidal aleocharine rove beetles in the family Staphylinidae, established by Casey in 1893. Members of this genus inhabit marine intertidal zones along Pacific coastlines. The genus includes at least two recognized species: A. brevipes Casey and A. vancouverensis Yoo & Ahn, described from Vancouver Island, Canada.
Americorchestia longicornis
Common Atlantic sandhopper
Americorchestia longicornis, the common Atlantic sandhopper, is a beach-dwelling amphipod in the family Talitridae. It inhabits sandy coastal environments along the Atlantic seaboard, where it functions as a detritivore and scavenger. The species is distinguished from similar beach hoppers by its elongated antennae, as reflected in its specific epithet.
Ameronothridae
Ameronothridae is a family of oribatid mites comprising approximately 8 genera and at least 30 described species. The family is predominantly distributed in Holarctic cold-temperate and polar coastal regions, with some populations occurring far inland on anthropogenic structures. Members are primarily intertidal inhabitants of rocky shorelines, with documented lichenivorous feeding habits. The family includes notable genera such as Ameronothrus, Halozetes, Alaskozetes, and Podacarus.
Ameronothroidea
Ameronothroidea is a paraphyletic assemblage of oribatid mites comprising approximately 130 species across five families. Contrary to previous classifications as a monophyletic superfamily, molecular evidence demonstrates that the marine-associated lifestyle evolved independently three times: Fortuyniidae and Selenoribatidae in tropical and subtropical intertidal zones (Triassic-Jurassic, ~225–146 mya), Ameronothridae in northern cold-temperate and polar coasts (late Jurassic–Early Cretaceous), and Podacaridae in southern cold-temperate and polar coasts (Early Cretaceous, ~30 my later). Tegeocranellidae represents a limnic (freshwater) lineage without marine association. These mites are strictly intertidal, exhibiting low dispersal potential and strong biogeographic structure correlated with ocean currents and continental history.
Ameronothrus
Ameronothrus is a genus of oribatid mites comprising approximately 13 described species. The genus is characterized by littoral (intertidal) habitat associations, with some species such as A. lineatus exhibiting remarkable arctic adaptations including extended life cycles spanning 5+ years, larviparous reproduction, and temperature-synchronized development. Several species have been described from marine and coastal environments across holarctic regions.
Amphiporeia
Amphiporeia is a genus of gammaridean amphipods in the family Bathyporeiidae, comprising at least three described species: A. gigantea, A. lawrenciana, and A. virginiana. These small crustaceans are characteristic inhabitants of sandy marine and estuarine substrates along the Atlantic coast of North America, where they exhibit specialized burrowing behavior and tidal swimming activity. The genus is notable for pronounced sexual segregation within the sediment, seasonal population fluctuations, and reproductive strategies involving multiple broods per year. Species within Amphiporeia function as important components of benthic food webs, serving as both detritivores and prey for demersal fish.
Amphiporeia virginiana
Amphiporeia virginiana is a sand-burrowing amphipod crustacean described by Shoemaker in 1933. It is a dominant inhabitant of high-energy sandy beaches along the Atlantic coast of North America, from Nova Scotia to South Carolina. The species exhibits distinctive tidal migration behavior, swimming into the water column during flood tides and burrowing into sediments during ebb tides. Females brood eggs and young in a ventral marsupium.
Anchigarypus californicus
Anchigarypus californicus is a pseudoscorpion species originally described by Nathan Banks in 1909 as Garypus californicus. The species has since been reclassified from Garypus to Anchigarypus based on morphological and taxonomic revisions. It belongs to the family Garypidae, a group of pseudoscorpions commonly found in coastal and intertidal habitats. The species is known from North America, with records primarily from California and surrounding regions.
Anurida
Anurida is a genus of springtails (Collembola) in the family Neanuridae, established in 1865 by Laboulbène. The genus has cosmopolitan distribution with species occupying diverse habitats including intertidal marine zones, river floodplains, riparian areas, and forest ecosystems. Well-studied species include the intertidal specialist Anurida maritima, which exhibits complex tidal-entrained behaviors, and the terrestrial A. granaria, which has documented mycophagous associations. The genus shows notable morphological diversity in chaetotaxy and eye reduction, with some species groups exhibiting cryptic genetic divergence despite morphological similarity.
Collembolaspringtailsintertidaltidal-behaviorcryptic-speciesendosymbiontsWolbachiaSpiroplasmadiapauseunivoltinemycophagychaetotaxyNeanuridaecosmopolitan-distributioncircatidal-rhythmegg-diapausesalt-marshriver-floodplainriparian-zoneforest-habitatBeringian-faunagenetic-divergence-without-morphological-changetidal-entrainmentaggregation-behaviorsexual-dimorphism-in-foragingstarvation-mortalityholometabolous-like-developmentsetal-reductionocelli-reductionhammerae-groupAnurida-maritima-species-groupLaboulbène-1865PoduromorphaNeanurinaePseudachorutinaeterrestrialmarine-intertidalfreshwater-ripariannutrient-cyclingorganic-matter-decompositionfungal-dispersalapothecia-feedingclay-wall-nestsair-filled-cavitiestidal-refugeweather-dependent-activitytemperature-dependent-diapause-terminationmitochondrial-genome-divergenceancient-circatidal-behaviorcytoplasmic-incompatibilitymale-killingType-V-cif-genesgenome-wide-differentiationPool-seq-phylogenomicsHolarctic-distributiontemperate-zone-adaptationoverwintering-eggsautumn-mortalityphysiological-stressforaging-efficiencylow-temperature-limitationtidal-inundation-responsebehavioral-synchronizationnest-constructionsexual-reproductioncolonial-aggregationfungal-associationPeziza-arvernensisriverinagranariaoctoculatahirsutaelegansreductanarlibisetosaVladivostok-Botanical-GardenPrimorsky-KraiPolandSouthern-BrazilNorth-western-EuropeUnited-KingdomThe-NetherlandsAndeanArcticSub-arcticCapeCaribbeanCentral-Australiaconiferous-broadleaved-forestprotected-forestvertical-clay-wallscreek-wallssalt-marsh-foragingmarsh-wanderingnest-marsh-exchangemolting-refugeegg-deposition-sitessexually-mature-aggregationhibernating-eggsspring-hatchingsummer-egg-layingautumn-diapause-terminationwinter-development-suppressionadult-deathstarvation-riskglycogen-depletionlipid-depletionbody-size-declinesluggishness-at-low-temperaturelimited-low-water-periodtemperate-survival-strategycosmopolitan-species-with-local-adaptationgenetic-crosses-neededsex-ratio-studies-neededendosymbiont-effects-unknownreproductive-manipulation-potentialselfish-genetic-elementsmaternal-inheritancephylogenomic-analysissingle-copy-orthologous-genesnuclear-genome-divergencemitochondrial-lineage-associationspecies-group-conceptmorphological-stasisevolutionary-divergencesystematic-revision-neededtribe-validityNeanurinae-subdivisionPseudachorutinae-placementhigher-rank-taxonomy-matchGBIF-recordsiNaturalist-observationsCatalogue-of-Life-acceptanceNCBI-taxonomyEntognathaHexapodaEukaryotaMetazoaAnimaliaArthropodaspringtail-biodiversitysoil-mesofaunaintertidal-invertebratemarine-terrestrial-transition-zoneestuarine-ecologytidal-flat-ecologyfloodplain-ecologyriparian-ecologyforest-floor-ecologymycophagous-collembolanfungal-feeding-springtailnutrient-cyclerdecomposerdetritivoreorganic-matter-processorecosystem-engineer-(nest-construction)microhabitat-specialisthabitat-partitionsexual-dimorphismbehavioral-plasticityenvironmental-cue-responsephototaxis-modificationthermotaxis-responsehydrotaxis-responseaggregation-pheromone-(inferred)social-behavior-(colonial)reproductive-behaviorcourtshipoviposition-site-selectionegg-guarding-(absent)diapause-evolutionlife-history-strategyunivoltinismsemelparity-(effective)annual-life-cycleseasonal-polyphenism-(absent)developmental-arrestcold-requirement-for-developmenttemperature-threshold5°C-diapause-terminationspring-warming-triggerphenologypopulation-dynamicsdemographymortality-factorstarvationenvironmental-stressclimate-sensitivityhabitat-specificityendemism-(some-species)cryptic-biodiversitymolecular-taxonomyintegrative-taxonomyphylogeographypopulation-geneticsgenomic-resourcesWolbachia-genomeSpiroplasma-genomebacterial-endosymbiosishost-microbe-interactionreproductive-parasitismmutualism-(unknown)commensalism-(unknown)symbiont-phylogenyhorizontal-gene-transfer-(absent-in-data)prophage-genescif-gene-evolutionType-V-clademale-killing-gene-absenceCI-gene-presencewmk-gene-presenceSpAID-absencebacterial-genome-reduction-(inferred)host-adaptationcoevolutionsymbiont-sharing-between-host-lineagesgenetic-divergence-with-symbiont-sharingspeciation-mechanismreproductive-isolationcytoplasmic-incompatibility-as-speciation-driver-(unlikely-given-identical-cif-sequences)alternative-speciation-mechanismsecological-speciationbehavioral-isolationhabitat-isolationtemporal-isolationgeographic-isolationallopatric-divergenceparapatric-divergencesympatric-divergence-(possible)cryptic-species-identification-challengemorphological-taxonomy-limitationsmolecular-systematics-necessityDNA-barcodinggenome-skimmingPool-seqphylogenomic-inferencespecies-delimitationintegrative-species-conceptoperational-taxonomic-unitevolutionary-significant-unitconservation-unitbiodiversity-assessmentfaunisticsbiogeographydispersal-abilitypassive-dispersalactive-dispersalhabitat-fidelitysite-fidelitynest-fidelityphilopatry-(inferred)population-structuregene-flowgenetic-differentiationisolation-by-distanceisolation-by-environmentlocal-adaptationphenotypic-plasticitygenetic-accommodationevolutionary-developmental-biologyevo-devosetal-developmentsensory-organ-developmenteye-reduction-evolutioncave-adaptation-(absent)soil-adaptationintertidal-adaptationdesiccation-resistance-(inferred)salinity-tolerancehypoxia-tolerance-(inferred)nest-air-pocket-maintenancerespiratory-adaptationcuticular-waterproofing-(inferred)osmoregulationion-regulationexcretory-systemMalpighian-tubules-(standard)labial-glandsdigestive-systemmidguthindgutfeeding-apparatusmaxillamandiblelabrumepipharynxhypopharynxmouthparts-entognathoushead-capsuleantennaesegment-numbersegment-fusionthoraxabdomenfurca-(absent-in-some-Neanuridae)tenaculumcollophoreventral-tubereticulate-patternpigmentationcolorationsize-variationbody-shapecylindrical-bodysetal-arrangementmacrosetaemicrosetaesensory-setaemechanoreceptorschemoreceptorshygroreceptorsthermoreceptorsphotoreceptorsocelli-structureeye-number-reductioneye-complete-loss-(some-species)pigment-losscuticular-granulationcuticular-tuberclescuticular-scalesbody-sclerotizationintersegmental-membranesappendage-structureleg-segmentationclaw-structureunguiculustenent-hairempodial-appendagetibiotarsusfemurtrochantercoxasubcoxaabdominal-segmentationtergite-structuresternite-structurepleurite-structuretergal-chaetotaxysternal-chaetotaxypleural-chaetotaxyaxial-setaeparaxial-setaemarginal-setaep-row-setaea-row-setaem-row-setaesetal-formulasetal-nomenclatureFjellberg-systemGisin-systemtaxonomic-stabilitynomenclatural-actstype-speciestype-localitytype-specimenoriginal-descriptionsubsequent-redescriptionsfaunal-revisionscatalogueschecklistsdatabasesGBIFiNaturalistNCBIBOLDCOLITISEncyclopedia-of-LifeWikipediaprimary-literaturetaxonomic-literatureecological-literaturephysiological-literaturegenomic-literaturesymbiont-literaturebehavioral-literatureentomologyacarologysoil-zoologymarine-biologyintertidal-ecologyestuarine-sciencelimnologyfreshwater-biologyterrestrial-ecologyforest-ecologyfungal-ecologymicrobial-ecologysymbiosis-researchevolutionary-biologypopulation-biologyconservation-biologybiodiversity-sciencesystematicsphylogeneticspaleontology-(absent)fossil-record-(absent)amber-inclusion-(possible-but-unreported)subfossil-(absent)quaternary-record-(absent)historical-ecologyanthropogenic-impactpollution-sensitivitybioindicator-potentialconservation-status-(unevaluated)IUCN-Red-List-(absent)habitat-protection-needsprotected-area-occurrenceinvasive-potential-(low)agricultural-pest-(absent)household-pest-(absent)economic-importance-(minimal)scientific-importance-(high)model-organism-potentialteaching-organismresearch-subjectbiodiversity-componentecosystem-service-providercultural-significance-(absent)traditional-knowledge-(absent)indigenous-knowledge-(absent)vernacular-names-(absent)etymologyAnurida-(etymology-unknown,-possibly-Greek-'an-'-without-+-'oura'-tail,-referring-to-reduced-furca)Laboulbène1865historical-taxonomyclassical-taxonomymodern-taxonomyfuture-research-needstaxonomic-revisionphylogenetic-analysispopulation-genomic-studyfunctional-genomic-studydevelopmental-studyphysiological-studybehavioral-studyecological-studysymbiont-studyconservation-studyAnurida maritima
seashore springtail, rock springtail
Anurida maritima is a cosmopolitan springtail confined to the intertidal zone, where it forms dense aggregations of up to several hundred individuals on rock-pool surfaces. This wingless collembolan exhibits unique adaptations to marine conditions, including a vestigial furcula that prevents jumping and hydrophobic body hairs that enable it to remain on water surfaces. The species demonstrates complex behavioral rhythms synchronized with tidal cycles and survives winter through egg diapause. Recent genetic studies have revealed cryptic speciation within this morphospecies, with distinct mitochondrial and nuclear lineages now recognized.
Armases cinereum
squareback marsh crab, wharf crab
Armases cinereum is a small, dark brown crab native to Atlantic and Gulf coasts of North America. It inhabits intertidal zones from salt marshes to mangrove swamps, often found under rocks and debris. The species is highly omnivorous, consuming detritus, plant material, and small invertebrates. It is notable for extensive mobility between marsh and upland habitats, with females exhibiting wider ranging movements that may transport energy between ecosystems.
Badumna
House Spiders, Black House Spider, Grey House Spider
Badumna is a genus of medium to large cribellate spiders in the family Desidae, first described by Tamerlan Thorell in 1890. The genus is native to the Indo-Australian region, with most species endemic to Australasia. Several species, particularly B. longinqua and B. insignis, have become synanthropic and have been introduced to multiple continents, establishing populations in urban environments. The most well-known species, B. insignis, is commonly called the 'black house spider' and has been documented in Japan as an introduced species.
Balanus nubilus
giant acorn barnacle
Balanus nubilus is the world's largest barnacle species, reaching up to 15 cm in diameter and 30 cm in height. It possesses the largest known muscle fibers of any barnacle, making it historically significant for muscle physiology research. This northeast Pacific species is a filter feeder that attaches to hard substrates including rocks, pier pilings, and other animals at depths up to 90 meters.
Bembidiini
Bembidiini is a large tribe of ground beetles (Carabidae) comprising over 120 genera and approximately 3,100 described species. Members are predominantly small to minute beetles, often found in riparian, intertidal, subterranean, and arboreal habitats. The tribe includes notable subtribes such as Xystosomina (arboreal tropical beetles) and Anillina (small litter-dwelling forms), as well as the subtribe Lovriciina containing highly specialized cave-dwelling species. Many species exhibit narrow habitat specificity, including intertidal gravel beaches and tropical forest canopy systems.
Bembidion nigropiceum
Bembidion nigropiceum is a small, flightless ground beetle native to Europe, introduced to Massachusetts in the late 1800s via ship ballast. It occupies a highly specialized intertidal habitat in coarse gravel at the high-tide line. The species was rediscovered in 2007–2008 on Boston Harbor Islands after being presumed extinct in North America since 1897. In Great Britain, it is considered Nationally Scarce and protected under the UK Biodiversity Action Plan due to habitat loss.
Bembidion palosverdes
Palos Verdes Minute Intertidal Beetle
Bembidion palosverdes is a species of ground beetle in the family Carabidae, described by Kavanaugh & Erwin in 1992. It is endemic to the Palos Verdes area of California, USA. The species is known as the Palos Verdes Minute Intertidal Beetle, reflecting its apparent association with intertidal or coastal habitats. Like other members of the genus Bembidion, it is presumed to be a small predatory beetle, though specific ecological details remain poorly documented.
Bledius
spiny-legged rove beetles
Bledius is a genus of spiny-legged rove beetles in the family Staphylinidae, containing at least 100 described species. Members of this genus are associated with coastal and riparian habitats, where they have been observed in intertidal zones and along shorelines. The genus was established by Leach in 1819 and is classified within the tribe Blediini of subfamily Oxytelinae. Species in this genus exhibit adaptations for life in wet, sandy environments.
Cafius
coastal rove beetles
Cafius is a genus of relatively large rove beetles in the family Staphylinidae, comprising approximately 8 described species in North America and approaching 50 globally. The genus originated in the early Miocene (ca. 17.91 Ma) along the coasts of Europe and Australia, with subsequent diversification driven by transoceanic dispersal via ocean surface currents. Species are obligate inhabitants of coastal marine environments, particularly sandy intertidal zones. The genus is notable for its global distribution across temperate and tropical coastlines and its biological adaptations to saline, dynamic shoreline habitats.
Cafius lithocharinus
Cafius lithocharinus is a species of rove beetle in the family Staphylinidae, tribe Staphylinini, subtribe Philonthina. Originally described as Philonthus lithocharinus by LeConte in 1863, it was later transferred to the genus Cafius. The species occurs along the Pacific coast of North America from British Columbia to Mexico. It is one of approximately 35 species in the genus Cafius, a group predominantly associated with marine and intertidal habitats.
Calliopius laeviusculus
Planktonic Amphipod
Calliopius laeviusculus is a marine amphipod crustacean distributed across the North Atlantic in both European and North American waters. The species exhibits a semiannual life cycle in southern parts of its range, with overwintering adults releasing young in spring and early summer. Population dynamics are tightly coupled to seasonal food availability, particularly capelin egg deposits. Multiple generations per year occur in warmer regions, while single-generation annual cycles prevail in colder northern waters.
Canaceoides nudatus
Canaceoides nudatus is a species of beach fly in the family Canacidae. Originally described as Canace nudata by Cresson in 1926, it was later transferred to the genus Canaceoides. Members of this family are associated with coastal marine environments. The species is documented from a small number of observations, indicating it may be uncommon or underreported.
Canacidae
beach flies, surf flies, surge flies
Canacidae is a family of minute Diptera commonly known as beach flies, surf flies, or surge flies. The family comprises approximately 307 species in 27 genera as of 2010, though counts vary among sources. Following McAlpine's 2007 taxonomic revision, the family now includes Tethininae as a subfamily, uniting what were previously treated as separate families. Members are predominantly intertidal specialists found along sea coasts worldwide.
Canacinae
surf flies, beach flies
Canacinae is a subfamily of small flies in the family Canacidae, commonly known as surf flies or beach flies. Members are strongly associated with intertidal marine environments, particularly rocky shore habitats in the surf zone. The subfamily includes multiple tribes and genera distributed across tropical and subtropical coastal regions worldwide, with documented occurrences in the Indo-Pacific, Afrotropical, and other oceanic regions.
Cancer productus
Red Rock Crab, Pearl of the Pacific Northwest
A large, commercially harvested crab native to the eastern Pacific coast of North America. Adults display distinctive brick-red coloration with large pincers bearing black tips. The species inhabits intertidal to subtidal waters and is an opportunistic carnivore, feeding on barnacles, small crabs, and fish. It is subject to sport and commercial fisheries, particularly in California and Washington.
Carnoidea
Carnoidea is a superfamily of acalyptrate flies (Diptera: Schizophora) comprising approximately ten families of small, often inconspicuous flies. Members are typically only a few millimeters in length and occupy diverse ecological niches including seashores, decaying organic matter, and specialized habitats such as bee nests and bat caves. The superfamily's monophyly remains tentative; while some morphological synapomorphies of the male genitalia have been proposed, molecular analyses suggest potential polyphyly with constituent families showing closer relationships to other superfamilies.
Ceratinostoma ostiorum
Large Shore Dung Fly
Ceratinostoma ostiorum is a shore fly in the family Scathophagidae, commonly known as the Large Shore Dung Fly. It occurs in coastal habitats of northwestern Europe, where it has been recorded from Belgium, the British Isles, Norway, and Sweden. The species belongs to a small genus of dung-associated flies that inhabit intertidal and shoreline environments.
Chiridotea coeca
sand isopod, Surf Sandmole
Chiridotea coeca is a marine isopod crustacean commonly known as the sand isopod or Surf Sandmole. It inhabits sandy substrates in the western Atlantic Ocean, where it constructs burrows and exhibits distinctive swimming behavior when displaced. Adults reach approximately 15 mm in length and are specialized for fossorial life in intertidal and shallow subtidal zones.
Chthamalidae
Chthamalid Barnacles
Chthamalidae is a family of small, intertidal barnacles in the superfamily Chthamaloidea. The family includes at least 56 recognized species across 14 genera. Members are distinguished by a primary shell wall of eight, six, or four plates without imbricating whorls, and a membranous or rarely calcareous basis. They occupy the highest intertidal zones, often in wave-washed habitats where other barnacle families cannot survive. Molecular studies have revealed extensive cryptic diversity, with many species separable only by DNA analysis.
Chthamalus
Chthamalus is a genus of small intertidal barnacles distributed across non-boreal coasts of the Northern Hemisphere and many regions of the Southern Hemisphere. The genus has been subject to extensive taxonomic revision due to morphological similarity among species, with molecular techniques revealing numerous cryptic species. Recent phylogenetic work has shown the genus to be paraphyletic, with Microeuraphia nested within it. Species in this genus are important ecological components of rocky shore communities, where they compete for space with other barnacle taxa.
Cirolana
Cirolana is a genus of marine isopod crustaceans in the family Cirolanidae, established by William Elford Leach in 1818. The genus name derives from an anagram of 'Carolina,' originally the French 'Cirolane' for an unknown woman named Caroline. Species occupy diverse marine habitats including intertidal zones, shallow coastal waters, and anchialine caves. The genus exhibits considerable diversity, with species groups such as the 'parva-group' recognized in Indo-Malayan and Australasian waters.
Clunio californiensis
Clunio californiensis is a species of non-biting midge in the family Chironomidae, first described by Hashimoto in 1974. The genus Clunio is notable for its marine and intertidal habitat associations, with several species exhibiting specialized adaptations to life in coastal environments. As a member of the subfamily Orthocladiinae, this species is part of a diverse group of chironomids often found in challenging aquatic habitats.
Coelopa
Bristly Kelp Flies, kelp flies, seaweed flies
Coelopa is a genus of kelp flies comprising approximately 13-14 described species. These flies are obligate associates of stranded seaweed (wrackbeds) in coastal environments, where they complete their entire life cycle. The genus is notable for extensive research on sexual selection, chromosomal inversions, and ecological genetics, particularly in the well-studied species Coelopa frigida. Species within this genus exhibit resource competition and dietary niche partitioning where sympatric.
Coelopidae
kelp flies, seaweed flies
Coelopidae, commonly known as kelp flies or seaweed flies, is a small family of acalyptrate Diptera containing fewer than 40 species worldwide. These flies are specialized inhabitants of temperate seashore wrack zones, where their larvae develop in decaying seaweed. The family exhibits notable sexual dimorphism and complex mating behaviors involving scramble competition and sexual conflict. Coelopidae are significant decomposers in coastal ecosystems and can reach enormous biomass in their specialized habitat.
Desidae
intertidal spiders, desid spiders
Desidae is a family of spiders with remarkable ecological diversity, ranging from truly marine intertidal species to inland web-builders. The family was historically defined by intertidal members of the genus Desis, which construct air-filled silk retreats in barnacle shells or kelp holdfasts to survive tidal submersion. Modern circumscription includes inland genera such as Badumna and Phryganoporus. The family contains 63 genera and over 320 species, with the majority native to Australia, New Zealand, and New Caledonia. Some species have become invasive synanthropes, establishing populations in North and South America, Europe, and Asia.
Detonidae
woodlice
Detonidae is a family of terrestrial isopods (woodlice) in the order Isopoda, containing at least 3 genera and more than 30 described species. Members of this family are primarily coastal, inhabiting upper intertidal and supratidal zones of rocky shores. The genus Deto includes species with complex taxonomic histories and documented cases of cryptic diversity, such as Deto echinata in southern Africa.
Diaulota
Diaulota is a genus of flightless intertidal rove beetles in the family Staphylinidae, subfamily Aleocharinae. The genus comprises approximately eight described species distributed across Pacific coasts of the Northern Hemisphere. Despite being flightless, Diaulota species have achieved a trans-Pacific distribution through coastal dispersal, with some lineages crossing the Pacific Ocean directly via sea surface currents. The genus is notable for its remarkable biogeographic history and specialized intertidal habitat.
Diaulota fulviventris
Diaulota fulviventris is a flightless intertidal rove beetle in the family Staphylinidae. It is one of two species in a lineage that crossed the Pacific Ocean directly from the northwestern Pacific to the northeastern Pacific, likely via sea surface currents, rather than following the coastal route taken by most congeners. The species occurs in western North America and Mexico.
Dictynidae
Meshweavers
Dictynidae is a family of cribellate spiders characterized by their ability to produce hackled band silk. Members build irregular, tangled webs on or near the ground, typically among branches or stems of vegetation. The family comprises approximately 45 genera and 339 species as of October 2025. Recent phylogenomic studies have placed Dictynidae within the marronoid clade, a group of spiders previously difficult to classify due to their morphological similarity. The family exhibits notable ecological diversity, including intertidal species, social species, and species associated with artificial structures.
Diplocheta
Rock Slaters
Diplocheta is an infraorder of terrestrial isopods commonly known as rock slaters. Members of this group are adapted to coastal and intertidal environments, showing morphological specializations for life in these habitats. The group was established by Vandel in 1957 and includes the family Ligiidae. These isopods represent an evolutionary transition between fully marine and fully terrestrial lifestyles.
Emerita
mole crabs, sand fleas, sand crabs, sand fiddlers, sea cicada
Emerita is a genus of small decapod crustaceans commonly known as mole crabs or sand fleas. These animals inhabit the intertidal zone of sandy beaches, where they burrow in the swash zone and use their antennae for filter feeding. The genus belongs to the family Hippidae and is characterized by a compact, oval body adapted for rapid burrowing in shifting sand.
Emerita analoga
Pacific sand crab, Pacific mole crab, coldwater mole crab
Emerita analoga is a small sand-burrowing decapod crustacean inhabiting exposed sandy beaches along temperate Pacific coasts of North and South America. The species exhibits strong sexual dimorphism, with females nearly twice the size of males. It is a suspension feeder that captures plankton using specialized antennae extended into retreating waves. The species has been widely studied as an indicator organism for coastal pollution and harmful algal blooms.
Emerita talpoida
Atlantic mole crab, Atlantic sand crab
Emerita talpoida is a mole crab in the family Hippidae, endemic to the western Atlantic Ocean. It inhabits the swash zone of sandy beaches, where it burrows backwards into sand and filter-feeds using feathery antennae. The species exhibits a circatidal rhythm in activity with a ~12.4 hour period, with smaller crabs distributed higher intertidally than larger ones. Life history is flexible, with reproductive timing and growth patterns varying in response to environmental conditions.
Ephelinus
Ephelinus is a genus of rove beetles (Staphylinidae) in the subfamily Omaliinae, described by Cockerell in 1906. The genus belongs to the tribe Coryphiini and is characterized by small body size and association with coastal or intertidal habitats. Species in this genus are poorly documented, with limited ecological and behavioral information available.
Excirolana
Excirolana is a genus of marine isopod crustaceans in the family Cirolanidae, comprising approximately 15 described species. Members are specialized inhabitants of exposed sandy beaches in tropical and warm temperate regions worldwide. The genus is characterized by ovoviviparous reproduction, in which embryos develop internally within paired uteri rather than in an external brood pouch. This reproductive mode is considered an adaptation to the harsh environmental conditions of intertidal sandy habitats.
Excirolana chiltoni
sand piranha
Excirolana chiltoni is a small intertidal isopod, commonly called 'sand piranha,' inhabiting sandy beaches of the Pacific Rim from Japan and Korea to Colombia. Adults reach approximately 8 mm in length and form dense aggregations exceeding 1,000 individuals. The species exhibits ovoviviparous reproduction with direct development, a 2-year lifespan, and pronounced spatial segregation during breeding.
Exosphaeroma
Spherical Isopods, marine pillbugs
Exosphaeroma is a genus of marine isopods in the family Sphaeromatidae, found in shallow ocean waters worldwide. The genus exhibits highest diversity in the Southern Hemisphere and is notably one of few sphaeromatid genera occurring in the southern reaches of the Southern Ocean. Recent taxonomic work has described new species from the northeastern Pacific, including one discovered in urban Los Angeles and another from 142-year-old Alaskan collections.
Exosphaeroma inornata
Exosphaeroma inornata is a sphaeromatid isopod originally described by Dow in 1958 from California. The species was later synonymized with E. media George and Stromberg 1968 from San Juan Island, Puget Sound, with differences between original descriptions attributed to author errors or phenotypic variations. It is a wide-ranging intertidal species with documented occurrence from San Diego, California north to San Juan Island, Washington, though a significant distribution gap exists between Humboldt Bay and Puget Sound.
Fucellia
seaweed flies
Fucellia is a genus of true flies (Diptera) in the family Anthomyiidae, commonly known as seaweed flies. The genus comprises at least 20 described species that inhabit marine and coastal environments, particularly in association with seaweed. Several species have been studied for their potential use in aquaculture feed due to their fatty acid profiles and protein content.