View allAll Photos Tagged Substrate
Substrate: Watercolour paper 180gsm
Light sensitive anthotype dye: Paprika in water
Application: immersion + brush
Opaque layer: Eukalyptus leaves.
Exposure time: 2days intermittent sunlight.
This SEM image shows carbon nanotube growth from printed iron oxide nanoparticles. The growth contains graphitic material and bundles of nanotubes. The image has been enhanced using Gimp software with the top crust of the forest shown in green, the CNT bundles shown in brown and the silicon substrate on which the forest was grown in blue.
Titled: Paris Blues
Ice Resin Substrate & Canvas
Made for the Ice Resin Creative Team Technique Tuesdays.
From Jack & Cat Curio.
For more info:
Editor's note: great story we posted today about how a NASA light technology, originally developed for plant growth experiments in space, is being used to reduce the side effects of various medical treatments, including those for cancer, wounds, etc. You can read more about the technology here: www.nasa.gov/topics/nasalife/features/heals.html. I love success stories like this!
Glowing red light from High Emissivity Aluminiferous Luminescent Substrate, or HEALS technology -- previously used to grow plants for space experiments -- also has been proven to aid in the healing of human wounds, burns, diabetic skin ulcers and oral mucositis – a common and extremely painful side effect of chemotherapy and radiation treatment. NASA has partnered with Quantum Devices Inc. (QDI), of Barneveld Wis., to develop the WARP 75 light delivery system device for wound healing. A two-year clinical trial using the WARP 75 device on cancer patients undergoing bone marrow or stem cell transplants, concluded that there was a 96-percent chance that the improvement in pain relief of those in the high-risk patient group was the result of the HEALS treatment. The clinical trial was funded by NASA's Innovative Partnerships Program at the Marshall Space Flight Center in Huntsville, Ala. The NASA program works with industry and commercial partners to spinoff space technology and adapt it for new, innovative applications.
Image credit: NASA/MSFC/David Higginbotham
View more images:
www.nasa.gov/topics/nasalife/features/heals_photos.html
Watch a video of HEALS in action:
www.nasa.gov/multimedia/videogallery/index.html?media_id=...
This ATC is an illustration board substrate with embossed metal from a Coke can covering it. I kept it simple with just a star embellishment because I wanted to show the texture and color of the metal (color added with alcohol inks). Hooray for recycling!
And no, the idea was not mine. Someone posted a link on one of my Yahoo art groups that showed an ATC with some pop-can metal that had been run through a Cuttlebug. I loved the idea SO much, that I asked for (and got!) a Cuttlebug for my birthday (which is 2 days from now).
You can expect more of these to come. LOL
going to live with careysniche. :)
Vacant shells in water. Colour variation from reddish-brown to purple brown depends partly on lighting and colour of substrate and whether shell is vacant or occupied, and in water or air.
1: whorls distinctly convex, but in profile shell is a depressed dome.
2 : debris lodged in suture.
Shell length 2.3 mm. North Yorkshire, September 2014. (leg. Jan Light.)
Illustrated pdf of this account available at
www.researchgate.net/profile/Ian_Smith19/contributions
Otina ovata (Brown, 1827)
Full SPECIES DESCRIPTION BELOW
Sets of OTHER SPECIES at: www.flickr.com/photos/56388191@N08/collections/.
Synonyms: Helix otis Turton, 1819; Otina otis (Turton, 1819); Gallericulum ovatum Brown, 1827.
Vernacular: Little ear-shell.
GLOSSARY BELOW
Shell Description
Usually up to 2.5mm long, maximum 3mm. Thin, semi-translucent. Very large body-whorl and single tiny bulbous spire-whorl forming lateral, inwardly-twisted apex; resembles tiny limpet or Haliotis shell 1Oo flic.kr/p/qfV1Vb . Whorls distinctly convex, but in profile shell is a depressed dome 2Oo flic.kr/p/qi2ddH . Aperture ear-shape, very extensive but does not expose interior of spire. Interior glossy. Inner and outer lips together form uninterrupted rim. Outer (palatal) lip smoothly-curved and thin; paler band within rim is area outside of foot-muscle attachment. Inner (columellar & parietal) lip forms almost transparent whitish shelf; no umbilicus 3Oo flic.kr/p/q1Dh3A . Exterior of shell superficially smooth, but magnification reveals sculpture of distinct growth lines and fine, regularly-spaced, parallel spiral striae forming lattice of oblongs 1Oo flic.kr/p/qfV1Vb ; growth lines sometimes emphasized by debris lodged against them 4Oo flic.kr/p/q1MiYR . Colour various shades of brown 2Oo flic.kr/p/qi2ddH , often darkened to dark chestnut-brown or purple-brown by closely adhering periostracum; groups of white specimens sometimes found (Killeen & Light, 1990), and newly hatched young are transparent showing yellow yolk in viscera. No operculum.
Body Description
Flesh white, slightly translucent. Head has large oral veil of two oral lappets and no protruding snout 5Oo flic.kr/p/qi8MYs . Mouth a ventral slit between lappets 9Oo flic.kr/p/q1CBfJ . Internal black sclerotized jaw near mouth shows as grey mark near junction of head and veil. Other blackish internal organs show grey through translucent head and body 6Oo flic.kr/p/q1CBwf . Strong short wide radula covers entire free surface of odontophore; up to 100 lateral teeth plus marginal teeth per row. Rudimentary cephalic tentacles consist of mound bearing large black eye 7Oo flic.kr/p/q1Dgzb . Mantle white; thin and transparent over mantle cavity; reflected as white rim at edge of shell-aperture 7Oo flic.kr/p/q1Dgzb . Mantle cavity has no special respiratory capillaries (usually present in less primitive pulmonates). Pneumostome near posterior of right mantle_rim 8Oo flic.kr/p/q1Dgum . Anus adjacent and anterior to pneumostome. Female and male genital openings on right side under posterior of oral lappet; penis a simple introverted tube. Foot white; sole oval, divided transversely at a third of way from anterior edge 9Oo flic.kr/p/q1CBfJ .
Internal anatomy
Image 10Oo flic.kr/p/qi2cfF shows features visible in specimen extracted from shell; includes jaw, transparent mantle skirt over mantle cavity containing no ctenidium or special respiratory capillaries, horseshoe-shaped loop of intestine, digestive gland surrounding intestine, stomach, ovotestis and very small kidney.
Key identification features
·Otina ovata
·Minute (2mm long) limpet-form shell with tiny spire.
·Lives near HW mark in humid chasms and caves, and in crevices.
Similar species
Several species of small limpet in NW Europe might have juveniles around 2mm with small spire, but none lives at HW mark.
Habits and ecology
In humid shaded positions on clean rock from splash zone of MHWN down to EHWN, including moist walls of caves 11Oo flic.kr/p/pmrqyZ , north facing walls of chasms and outer parts of not-heavily-silted crevices on north faces of reefs of slate, shale, chalk etc. Favours fissured rock, but not unstable rapidly-eroding outcrops. Unlikely to occur where turbid water deposits film of mud over rock surfaces.
Obligatory hygrophile, unable to survive constant immersion of entire 12-hour tidal cycle so not below EHWN, but needs air humidity near 100%, becoming shrivelled and inert after twelve hours at 90%. Negatively geotactic when submerged, promptly moving up to escape total immersion when possible 6Oo flic.kr/p/q1CBwf . If exposed to non-humid air, moves promptly to humid shelter if possible, or clamps down onto substrate if none accessible.
Often associated in crevices with Melarhaphe neritoides, Littorina saxatilis, Cingula trifasciata, Auriculinella bidentata, Lasaea adansoni, Spirorbis borealis (tube worm), and Chthamalus spp. (barnacles). On open surfaces, active during periods of wave-splash, and at other times may venture out in very humid weather, especially if can shelter in dead barnacle shell, tuft of Lichina pygmaea or byssus of small Mytilus edulis. Positively thigmotactic, so often found in packed groups of about ten that conserve moisture.
Respiration is with atmospheric air admitted to the mantle cavity through a pneumostome 8Oo flic.kr/p/q1Dgum , but, unlike most pulmonates, O. ovata lacks special respiratory capillaries in the mantle cavity 10Oo flic.kr/p/qi2cfF . Broad lateral tracts of foot-surface 5Oo flic.kr/p/qi8MYs may have accessory respiratory function as blood comes here to body-surface under very thin epithelium through which respiratory interchange might easily be possible (Morton, 1955); probably sufficient respiration for slow-moving animal with small volume.
Feeds by scraping wave-lodged diatoms and filamentous algae from rock surface with radula while jaw grips on substrate. Food particles compacted at mouth with copious mucus from suprapedal gland on upper surface of anterior lobe of foot. Stomach with rotating protostyle of mucus and faeces, similar to that of bivalves, is most primitive yet described in a pulmonate (Morton, 1955) 10Oo flic.kr/p/qi2cfF . Faecal string never compressed into pellets, much more loosely compacted than in prosobranchs 9Oo flic.kr/p/q1CBfJ ; unlike them, has no ctenidium to be fouled and anus does not discharge into pallial cavity. Small kidney in front of looped intestine opens into pallial cavity with no water current to carry discharges out of cavity 10Oo flic.kr/p/qi2cfF ; probably assisted by accessory excretion from amoebocytes in broad lateral tracts of foot (Morton, 1955).
Travels by advancing anterior third of foot, fixing it to substrate and then bringing up the rest of the foot. Foot moved by muscles and disposition of blood in pedal sinus.
Breeding: protandrous hermaphrodite with no clear cut separation of male and female phases, each animal produces sperm in September – December, followed by an egg-producing phase December - June. Copulation with simple penis occurs before late March. Spawns in late May/ early June. Loose clusters of 20-30 eggs in tough, yellow/straw-coloured mucal secretion, 4-5mm across, loosely attached to substrate in humid conditions where adults live. Operculum, but no velum, present in embryos. Young hatch as crawlers with transparent shell revealing viscera yellow with egg-yolk in apical bulb. Uncertain if annual life cycle, but presence of all sizes simultaneously suggests biennial or longer.
Search technique “if properly searched for it would doubtless be found in every suitable locality” (Jeffreys, 1869).
Take a torch and large hand lens to help detect the tiny white glistening blobs of flesh, or, in late May and early June, the larger (4 or 5mm across) yellowish egg masses. Choose a humid misty day, if possible, as O. ovata is then more likely to emerge from cover, and visit as soon after high tide as access is possible; wellingtons or waders may help early access to caves with entrances still awash. Seek, in fissured rock, a cave or chasm that is narrow, so likely to retain humid air and exclude direct sun 11Oo flic.kr/p/pmrqyZ . Search wet and damp rock faces around high water mark; sometimes different coloured algal films indicate differences of moisture. Shaded, north-facing faces of fissured reefs may have some within crevices, but splitting them open is destructive of the habitat and should be done very sparingly, if at all. If you take specimens for study, transport them in a wet air-tight box that preserves 100% humidity. At home keep box in a fridge between 6°C and 10°C. Examination and photography can be of animal in seawater to save from dehydration, but it will become inactive and drown if kept submerged for more than a few hours.
Also, see 12Oo flic.kr/p/q1CALh & 13Oo flic.kr/p/qicbXR .
Distribution and status
Sparse scattered records, but can be locally common. Probably overlooked because of its small size and specialized habitat requiring targeted searching, and unfamiliarity of recorders with it as often omitted from id guides of both terrestrial and marine molluscs. Known distribution: Britain, Ireland, Normandy and Brittany. Isolated records of beached dead shells from N.W. Spain, S. Portugal and Sardinia. GBIF map www.gbif.org/species/5189862 . NBN UK map species.nbnatlas.org/species/NBNSYS0000041447 has records on S. and W. coasts of Britain from Isle of Wight to Mull, but there were 19th Century east-coast finds in Northumberland and Yorkshire (Forbes & Hanley, 1853), and Jan Light found live specimens in N. Yorkshire in September 2014.
Acknowledgements
I am indebted to Dr Jan Light for providing specimens and sharing her expertise at the visit by the Conchological Society of G.B. & Ireland to N. Yorkshire in September 2014. I gratefully acknowledge Dr C.M. Cunha and Dr G. Rosenberg for help with sources and their interpretation.
Links and references
Eales, N.B. 1967. The Littoral fauna of the British Isles 4th ed. Cambridge, Cambridge University Press.
Forbes, E. & Hanley S. 1849-53. A history of the British mollusca and their shells. vol. 3 (1853) London, van Voorst. (As Otina otis; Free pdf at archive.org/details/historyofbritish03forb Use slide at base of page to select pp.320-323.)
Hayward, P.J. & Ryland, J.S. 1995. Handbook of the marine fauna of north-west Europe. Oxford, Oxford University Press.
Jeffreys, J.G. 1862-69. British conchology. vol. 5 (1869). London, van Voorst. (As Otina otis; Free pdf at archive.org/stream/britishconcholog05jeffr#page/108/mode/2up . Use slide at base of page to select pp.109-111.)
Killeen, I. & Light, J.M. 1990. Observations on Otina ovata (Brown): a little known pulmonate. J. Conch., Lond 33: 317 – 318.
McMillan, N.F. 1968. British shells. London, Warne.
Marshall, J.C. 1913. Additions to British conchology. Part 7. J. Conch., Lond. 14: 65-77. 12Oo flic.kr/p/q1CALh
Melville, J.C. 1918. Otina otis Turton at St Mary’s, Scilly. J. Conch., Lond. 15: 261. 13Oo flic.kr/p/qicbXR
Morton, J.E. 1954. The crevice faunas of the upper intertidal zone at Wembury. J. Mar. biol. Ass. U.K. 33: 187 – 224. plymsea.ac.uk/view/year/1954.html#group_M
Morton, J.E. 1955. The functional morphology of Otina otis, a primitive marine pulmonate. J. Mar. biol. Ass. U.K. 34: 113 – 150.
(Free pdf at core.kmi.open.ac.uk/download/pdf/6185241.pdf . pp144 - 145 missing from pdf). Also plymsea.ac.uk/view/year/1955.html#group_M
Sosso, M. & Dell’Angelo, B. 2010. Prima segnalazione di Otina ovata (Brown, 1827) (Systellomatophora: Otinidae) in Mediterraneo Boll. Malacol. 46: 1-3.
Current taxonomy: World Register of Marine Species (WoRMS) www.marinespecies.org/aphia.php?p=taxdetails&id=140661
Glossary
amoebocytes – mobile cells (moving by pseudopodia like amoeba) in invertebrate bodies that variously digest food, dispose of waste, fight infection etc.
aperture – mouth of gastropod shell; outlet for head and foot.
apical - at the apex.
cephalic – (adj.) of or on the head.
columella - solid or hollow axial “little column” around which gastropod shell spirals; hidden inside shell, except on final whorl next to lower part of inner lip of aperture where hollow ones may end in an umbilicus or siphonal canal.
columellar – (adj.) of or near central axis of spiral gastropod.
columellar lip - lower (abapical) part of inner lip of aperture.
coll. – in the collection of (named person or institution) (cf. legit).
ctenidium – comb-like molluscan gill; usually an axis with a row of filaments either side.
epithelium – tissue forming outer layer of body surface, “skin”.
EHWN – extreme high water neap tide (the weakest high tides of the year i.e. those that rise the least, usually near June and December solstices)
geotactic – (adj.) of species that moves towards pull of gravity (positively geotactic) or away from it (negatively geotactic). (Synonyms: gravitaxic, ? geotaxic.)
hygrophile – species that prefers moist conditions; often at water’s edge, but not permanently submerged. obligatory hygrophile – unable to survive out of moist conditions.
introverted – turned in on itself.
legit – (abbreviation; leg. or lgt.) collected/ found by (compare with coll.)
mantle – sheet of tissue that secretes the shell and forms a cavity for the gill in most marine molluscs (but not in adult nudibranchs), part or all of dorsal body surface when shell absent or internal.
MLWN – mean low water neap tide level (mean level reached by weakest low tides for a few days every fortnight. i.e. those that fall the least).
MHWN – mean high water neap tide level (mean level reached by weakest high tides for a few days every fortnight. i.e. those that rise the least).
odontophore – firm, approximately ellipsoid, structure of cartilage supporting radula. Protruded like a tongue to operate radula.
operculum – plate of horny conchiolin, rarely calcareous, used to close shell aperture.
oral lappets – flaps of flesh by mouth.
oral veil – flat anterior extension of head (may consist of lappets).
ovotestis – hermaphrodite organ serving as both ovary and testis.
palatal lip - outer lip of gastropod aperture.
pallial – (adj.) of the mantle.
parietal lip – (=parietal wall) part of inner lip of gastropod aperture, adapical of columellar lip.
pedal – (adj.) of the foot.
periostracum – thin horny layer of proteinaceous material often coating shells.
plankton – animals and plants that drift in pelagic zone (main body of water).
pneumostome - breathing pore in mantle of pulmonate molluscs.
protandrous hermaphrodite – each individual starts mature life as a functioning male, later changing to female function.
pulmonate – (adj.) of terrestrial and freshwater, air-breathing, slugs and snails.
radula – ribbon of chitinous teeth extruded on a tongue-like structure (odontophore) to rasp food.
rec. – recorded by (person who submitted record, may be different from leg. and coll. persons/institution).
sensu lato – (abbreviation s.l.) in the wide sense.
sensu stricto – (abbreviation s.s.) in the strict sense, excluding species that have been confused with it.
stria – very narrow spiral groove or ridge (plural: striae)
taxis – directional locomotary response to external stimuli such as light, gravity, temperature or chemicals.
thigmotactic – (adj.) of animal that moves towards (positively thigmotactic) or away (negatively thigmotactic) from physical contact with others.
umbilicus – cavity up axis of some gastropods, open as a hole or chink on base of shell, often sealed over.
velum – bilobed flap on veliger larva, with beating cilia for swimming.
A supermacro of a circuit board when glaring golden sunlight emanating across the etched copper pathways amongst all of the green substrate.
AWESOME when viewed in LIGHTBOX!!!!!
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The ballast & substrate had been completely removed from near the mid-way point nearly to the northern portal dropping the floor by about 18 inches which had flooded. Even though it was mid Summer the cold water was a shock to the system, only having my trainers on but needs must. The view is looking north with bridge 488 beyond, the lowest on the line.
Caroline in Amsterdam
Original Painting by Cara Buchalter of Octavine Illustration
Painted in gouache on Plywerk, a hand-crafted substrate wood board handmade in Portland, Oregon.
For further information please visit my blog:
www.octavineillustration.blogspot.com
A bit about this image:
I do not drive. Nor do I ride a bicycle, skateboard, or scooter. I do not rollerskate unless in a rink, and as a West Coaster I never had occasion to ice skate outside of doors.
I could not tell you why I don't see lampposts, cars, or other pedestrians as I wander through my somewhat confused existence, but I live in my head, focused on my world.
As vehicular transport eludes me and I prefer to walk or take the bus, I found it odd that I should be a part of Portland's Cycle Seen project.
The painting pictured is currently on display in NE Portland at Cup and Saucer as part of a city-wide exhibition featuring bicycle art.
This image was taken from my memories of my trip through Holland with my sis. In Holland there are bicycle freeways taking one out of town and through the pastoral countryside. Without cars to worry me, I was free to ride past the windmills and frolicking baby goats. I most vividly remember my sis shouting out, "This is the best day ever!" as we rode through the Dutch farmlands. Indeed it was.
©2008 Cara Buchalter. Please don't take and use the images without permission, thanks.
Crustose lichens form a crust that strongly adheres to the substrate (soil, rock, tree bark, etc.), making separation from the substrate impossible without destruction. The basic structure of crustose lichens consists of a cortex layer, an algal layer, and a medulla. The upper cortex layer is differentiated and is usually pigmented. The algal layer lies beneath the cortex. The medulla fastens the lichen to the substrate and is made up of fungal hyphae. The surface of crustose lichens is characterized by branching cracks that periodically close in response to climatic variations such as alternate wetting and drying regimes.
Size: 6”x6”
Tesserae: Scrap stained glass, millefiori, vitreous tile, and salvaged mirror, on 1/4" environmental MDF
Statement:
This work depicts an abstract forest at dawn. On a salvaged mirror substrate, I have used scrap stained glass for the leaf canopy and the hilly ground, with accents of Italian glass millefiori. I left the tree trunks and branches as "open cut-outs" with no tessera, which allows the mirror substrate to show through and form the tree trunks and branches. The trees are all "interlocked" with one another by their web of branches. My intention with the overall composition is to suggest that between the heavens and the earth we are all interconnected ("Beyond Borders") and by using the mirror as a major element, I hope to remind anyone who views the piece and sees their reflection in the trees, that they, too, are part of that infinite connection.
About me:
My name is Francesca De Lorme and I am the owner of Studio Fresca in northeastern Vermont. While I enjoy art of all kinds and work in a variety of media, as well as teach art part-time at nearby Burke Mountain Academy, I am totally and irrevocably smitten with mosaic. When I'm not delving into dumpsters or scavenging around salvage yards, I create Mixed-Media Mosaic Art using primarily recycled, salvaged and reclaimed materials — and I love the entire process. The art and craft of making mosaics is totally engrossing to me because it involves the heart in the passion of creation, the head in fitting together all the elements of the puzzle, and the hands in fine craftsmanship. For me, art is both interaction and expression; an exploration of discovery that perfectly weds the mind, the soul and the body in an ongoing, thought-provoking, and always entertaining, dialog...with myself, with the world around me — and with ALL the stuff, both physical and metaphysical, of life. I am affiliated with several local and national artists associations and my work has been consistently chosen for exhibit in major and minor juried shows. I also offer small group and individual classes; serve as Artist-in-Residence for schools; plan, design and coordinate community public art projects; and sell some mosaic materials and supplies.
Francesca De Lorme
Studio Fresca
Website: www.studiofresca.com
Vermont, USA
Example of asbestos-containing exterior paint on concrete substrate with significant damage, resulting in friable debris throughout vicinity of material application.
Substrate, one of my favorite algorithms.
If you're into algorithmic art, pretty much anything in the Complexification Gallery is amazing, but this Substrate algorithm by Jared Tarbell has been a favorite of mine for years. Check out his amazing work.
These images were generated by a Windows screensaver I'm working on.
Got Windows 10? Want to try it out? You can Download the Windows 10 screensaver here. It's a work in progress, so let me know any issues you have.
Other screen captures below...
Full Journal here on UKAPS.org - ukaps.org/forum/viewtopic.php?f=35&t=15952
Tank specs
Tank: ADA Cube Garden Mini M - 36x22x26cm / 5mm optiwhite glass
Hardscape: ADA Yamaya Rock, ADA Hornwood
Co2: Pressurised via Do!Aqua Music Glass - Mini 10D, Music Counter and ADA grey parts set
Lighting: ADA Mini-M - Solar 27W light
Filtration: Fluval 205 external to
Outlet - Do!Aqua Violet Glass mini MP-1 10D
Inlet - Do!Aqua Violet Glass mini MV-1 13D
Heating: None yet as its in a centrally heated room. I may add an inline heater in the winter
Substrate: ADA Power Sand Special topped with ADA Africana Powder - Penac P & W and tourmaline for good measure
Ferts per day: ADA Step 1 and Brighty K
Critters: Red Cherry Shrimp, fish undecided yet
plants to include - Ferns, tennelus, hairgrass, fissidens, mosses, Bolbitus and a carpet of Glosso
Live shell has a substantial light brown periostracum which is raised into many slightly waved, spiral ridges.
The periostracum reduces translucency of live specimens so the viscera are only faintly discernible (See also fig. 04 flic.kr/p/2gdwYwJ ) . The white, apical protoconch lacks a periostracum.
Shell height 10 mm. ELWS, Gairloch, north-west Scotland, May 2019. Leg. D. McKay & S. Taylor.
Full SPECIES DESCRIPTION below
PDF available at www.researchgate.net/publication/377437235_Velutina_velut...
Sets of OTHER SPECIES:
www.flickr.com/photos/56388191@N08/collections/
Velutina velutina (O. F. Müller, 1776)
Meaning of scientific name:
Velutina (Latin) = velvety (referring to the texture of the live, periostracum-coated shell surface).
Synonyms: Bulla velutina Müller O.F., 1776; Velutina laevigata (O. F. Müller, 1777); Velutina laevigata var. alba Jeffreys, 1867.
Current taxonomy: World Register of Marine Species (WoRMS) www.marinespecies.org/aphia.php?p=taxdetails&id=141905
Vernacular: Velvet snail (English); Cragen felfed (Welsh); Gewone fluweelhoren (Dutch); Fløjlsskæl (Danish); Sjöpungsnäcka (Swedish): Glatte Samtschnecke (German); Veloutée lisse (French).
GLOSSARY below.
Shell description
In Britain, the shell height is commonly about 10 mm 1Vv flic.kr/p/2gdx1kd , with a usual maximum of 18 mm (McMillan, 1968) and extreme of 22 mm (D.W. McKay, in litt. 2019). Specimens from Greenland are larger and thicker than in Britain (Jeffreys, 1867). The shell depth (perpendicular distance from the summit of a living specimen to substrate), is about 50% of shell height (see 1Vv flic.kr/p/2gdx1kd for illustration of dimension terms). The shell has thin walls and only two and a half rapidly-expanding, tumid whorls with the body whorl constituting the great majority of the shell. The sutures between the whorls are deep but obscured by the thick velvety periostracum on living specimens. The apical angle is wide with the apex often recessed into a depression making it almost involute 2Vv flic.kr/p/2gdwZh1 .
The slightly glossy, translucent, white or pinkish-white calcareous shell has a sculpture of many very fine growth lines crossed by many very fine, low spiral ridges, forming a faint reticulated pattern 2Vv flic.kr/p/2gdwZh1 . On live shells, these lines are concealed beneath the substantial light brown periostracum which is raised into many slightly waved, spiral ridges 3Vv flic.kr/p/2gdwHru . Occasionally, the periostracum is white (Telnes, 2019). The brown periostracum reduces the translucency of live specimens so the viscera are only faintly discernible 3Vv flic.kr/p/2gdwHru & 4Vv flic.kr/p/2gdwYwJ . The white, apical protoconch lacks a periostracum. Within 24 hours of drying, the periostracum loses the spiral ridges and shreds into bristle-like fragments 5Vv flic.kr/p/2gdwYds , and it readily flakes off. Consequently, strandline shells 2Vv flic.kr/p/2gdwZh1 usually have little or no periostracum and are white or pinkish white.
The aperture 1Vv flic.kr/p/2gdx1kd is almost circular, about 90% of the shell-height, and about three times as large as visible whorls in apertural view. The palatal and columellar lips run into each other in a smooth curve; the parietal lip is very short but broader than the columellar lip. The adapical angle of the aperture is rounded. There is no umbilicus but on large older specimens the apex may protrude slightly, and the whorls are more loosely coiled; sometimes with the body whorl separating slightly from the columellar lip to give the false impression of an umbilical slit.
The external colour of a live shell is brown when the periostracum is present and translucent white or pinkish white when the periostracum is lost 5Vv flic.kr/p/2gdwYds ; pink being more frequent and intense in the south of its range. Internally, the shell is white or pinkish white, but appears brown when the external periostracum shows through it 1Vv flic.kr/p/2gdx1kd . The large round aperture resembles that of limpets and, like them, V. velutina has no operculum to seal it.
Body description
The body is white 6Vv flic.kr/p/2gdwGBP , sometimes with a faint yellowish or pinkish hue (Jeffreys, 1867), varying in translucency in its different parts, with a very fine opaque white stipple most noticeable where translucency is strongest 7Vv flic.kr/p/2gdwXyX . The mantle varies from white or cream to yellowish white with a fine, opaque, white stipple 7Vv flic.kr/p/2gdwXyX (“frosted with white points” Fretter & Graham, 1978). The mantle edge is thickened by large, inflated, puckered, connective tissue cells 8Vv flic.kr/p/2gdwXsz blocking the entrance to the mantle cavity, except for the inhalant and exhalant passages. The connective tissue may protrude beyond, but not reflect onto, the palatal lip (anterior of aperture of live specimen) 9Vv flic.kr/p/2gdwX4U . Usually, the mantle is reflected slightly onto only the columellar and parietal lips (posterior of aperture of live specimen). The flat head and its smooth, tapering cephalic tentacles are coloured as the body. The anterior of the head is widely truncated as it has no exterior snout, but the short yellow, inverted proboscis is sometimes visible within the semi-transparent head 10Vv flic.kr/p/2gdwFM2 . There is an eye on a basal swelling at the distal side of each cephalic tentacle. A white or yellowish penis 6Vv flic.kr/p/2gdwGBP, and 7Vv flic.kr/p/2gdwXyX is located behind the right tentacle of all adults as, unusually for Caenogastropoda, the species is hermaphrodite.
The dorsal surface of the foot is coloured as the body, but the opaque stipple may be difficult to discern as the foot has weak translucency 11Vv flic.kr/p/2gdwWUa . When in motion on a flat surface, the unstippled white sole is ovate with a constriction close to the broadly curved anterior shaped like an axehead with flexible corners 8Vv flic.kr/p/2gdwXsz . The foot readily folds transversely at the constriction. Through the inhalant and exhalant passages in the pallial connective tissue it is sometimes possible to partially see within the mantle cavity 12Vv flic.kr/p/2gdwrrG the ctenidium; the smaller, but similarly comb-shaped osphradium (misinterpreted as a second ctenidium in early works [Forbes & Hanley, 1853 and Jeffreys,1867]); the hypobranchial gland; and rectum. If the relaxed and killed animal is removed from the shell and the black pigment 13Vv flic.kr/p/2gdwrg6 rubbed off the translucent mantle, it should be possible to see 14Vv flic.kr/p/2gdwqXR & 15Vv flic.kr/p/2gdwVUp the ctenidium and osphradium, the right columellar muscle; the smaller left columellar muscle; the very extensive white hypobranchial gland lining the entire roof of the mantle cavity to the right of the ctenidium; the genital ducts; the rectum; the auricle and ventricle of the heart; and the ovotestes.
Key identification features
Velutina velutina
1) When live, white, or pinkish white, calcareous shell is covered, except apical protoconch, by substantial brown periostracum that is raised into spiral ribs 1Vv flic.kr/p/2gdx1kd . Periostracum distorts when dry 5Vv flic.kr/p/2gdwYds .
2) When live, shell is weakly translucent and only indistinctly shows the viscera 4Vv flic.kr/p/2gdwYwJ & 16Vv flic.kr/p/2gdwVHc .
3) Aperture large and almost circular; about three times as large as visible whorls in apertural view 1Vv flic.kr/p/2gdx1kd .
4) Columellar lip has no umbilicus or groove 1Vv flic.kr/p/2gdx1kd .(Gap between body whorl and aperture sometimes occurs on large old specimens and might be mistaken for umbilical groove).
5) Spire does not usually protrude beyond body whorl; apex often recessed into a depression 2Vv flic.kr/p/2gdwZh1 . Apex on large old shells may protrude slightly
6) When live and active, mantle may extend beyond the aperture rim, but only reflected onto the shell at the rear of the aperture (columellar/ parietal lips) 9Vv flic.kr/p/2gdwX4U .
7) Flesh translucent white with fine, opaque white stipple 6Vv flic.kr/p/2gdwGBP . Mantle white, cream and/or yellowish white 7Vv flic.kr/p/2gdwXyX .
Similar species
Velutina plicatilis (O. F. Müller, 1776)
1) Shell is horn coloured, made principally of thick, slightly hispid periostracum; not raised into spiral ribs. Flimsy, thin, white, interior calcareous layer readily flakes off when dry, leaving just the periostracum 20Vv flic.kr/p/2gdwUPJ .
2) When live, shell is translucent often showing form and colour of viscera within; mainly yellow and orange 16Vv flic.kr/p/2gdwVHc .
3) Large, elongate oval aperture; about three times as large as visible whorls in apertural view 20Vv flic.kr/p/2gdwUPJ .
4) Columellar lip has no umbilicus or groove 20Vv flic.kr/p/2gdwUPJ .
5) Spire does not protrude beyond body whorl; usually recessed into a depression 20Vv flic.kr/p/2gdwUPJ .
6) When live and active, mantle is obviously reflected a short way onto the shell all around the aperture 16Vv flic.kr/p/2gdwVHc .
7) Flesh and mantle bright yellow or orange 16Vv flic.kr/p/2gdwVHc .
Lacuna pallidula (da Costa, 1778)
1) When live, calcareous, white shell is covered by substantial periostracum that is smooth, apart from numerous growth lines; brown or olive-brown on adults 21Vv flic.kr/p/2gdwpr4 . Periostracum readily flakes off when dry 22Vv flic.kr/p/2gdwCSQ .
2) When live, adult shell is opaque 21Vv flic.kr/p/2gdwpr4 .
3) Large, D shaped aperture about same size as visible whorls in apertural view 22Vv flic.kr/p/2gdwCSQ .
4) Columellar lip has large groove (chink) and umbilicus 22Vv flic.kr/p/2gdwCSQ .
5) Low spire protrudes, not recessed into a depression 22Vv flic.kr/p/2gdwCSQ .
6) When live and active, mantle may protrude very slightly, but is not reflected onto the shell 21Vv flic.kr/p/2gdwpr4 .
7) Flesh usually white, often with some yellow on snout, penis and parts of foot. Sometimes flesh is pink or whitish grey 21Vv flic.kr/p/2gdwpr4 .
Capulus ungaricus
1) When live, white, calcareous shell is covered, including apical protoconch, by substantial pale, straw-coloured periostracum which is raised into spiral ribs 23Vv flic.kr/p/2gepyX3 . Periostracum extends beyond aperture as fragments which form a fringe on adults.
2) When live, shell is weakly translucent.
3) Aperture large and almost circular with only the small curled spire visible in apertural view 25Vv flic.kr/p/2i3gDm7
4) Columellar lip has no umbilicus or groove.
5) Small, downward spirally coiled spire protrudes almost centrally from beyond body whorl. Apex not recessed into a depression, and turned slightly to the right of the animal 23Vv flic.kr/p/2gepyX3 & 25Vv flic.kr/p/2i3gDm7 .
7) Flesh yellowish with white speckles . Proboscis permanently extended (Graham, 1988).
8) Juveniles often found near open end of Pomatoceros tubes 24Vv flic.kr/p/2gepjfF ; adults near bivalves and Turritella, purloining food particles brought in by the hosts’ inhalant currents, or their pseudofaeces.
Habits and ecology
V. velutina lives mainly sublittorally to depths of 1000 metres Hayward & Ryland (1995) on hard substrate, especially shelly ground (Forbes & Hanley, 1853), where its unitary ascidian prey, Ascidia, Phallusia and Styela coriacea occur (Fretter & Graham, 1962). Rarely, live specimens are found at ELWS in northern Scotland.
Respiration is with inhalant water brought into the mantle cavity via a passage through the connective tissue by the left of the head 17Vv flic.kr/p/2gdwE6m . In the cavity, it first passes through the reddish osphradium 12Vv flic.kr/p/2gdwrrG which tests the water quality and probably removes large particles of detritus. It then passes through the dull yellow ctenidium which acquires oxygen from the water for the haemolymph (‘blood’) passing through it and releases carbon dioxide which passes with the water out of the animal via an exhalant passage through the connective tissue on the right side of the body. Locomotion is on the large foot lacking a medial dividing groove on the sole. When live, the foot usually remains in contact, limpet-like, with the substrate. V. velutina feeds by biting open the tough test of unitary ascidians to access the soft inner parts. The rectum and anus 12Vv flic.kr/p/2gdwrrG are near the exhalant passage where faeces exit the animal with the exhalant water. Clark in Jeffreys (1867) reported that it "discharges a very copious and tenacious clear white slime" which may have protective qualities. It may breed all year as veliger larvae have been seen in summer and autumn off Plymouth, S. England (Fretter and Graham, 1962), and mating at 3ºC and ova have been photographed in Norway in December and January . If breeding is triggered by temperature it is likely that it takes place at different dates at different levels of its great depth range in different geographical areas. Fretter and Graham (1962) considered it to be a simultaneous hermaphrodite. A photo of mating 18Vv flic.kr/p/2gdwVcs shows a couple lying head-on, foot to foot, on their left sides so their right-side genitalia are adjacent. In the photo, the massively engorged penis of only one of them can be seen to be penetrating the other. For oviposition, the radula cuts round holes a few mm from each other in the ascidian. The foot positions large, spherical pot-shaped egg capsules in the holes 19Vv flic.kr/p/2gdwDNh and 19.1Vv flic.kr/p/2oX6A8w. Only the transparent plug in the opening of the capsules is visible on the surface of the ascidian. Each capsule contains hundreds of unshelled ova in an albuminous fluid. The plug is freed from the opening for the planktonic bilobed veliger larvae to escape.
Distribution and status
V. velutina has a circumpolar distribution from the high Arctic southwards to Galicia, Spain; Cape Cod, Atlantic USA; San Diego, Pacific USA; and Japan. There are very few records from thwe continental coast of the southern North Sea. GBIF map www.gbif.org/species/2299230 . It occurs widely around Britain and Ireland where there is suitable hard substrate with ascidians. Most live records are sublittoral. Lttoral finds are usually dead, but there are some live littoral records from northern Scotland. There are few records, dead or alive, from the north-east Irish Sea, mid Wales, south-west England and between Kent and the Humber; Estuary. U.K. interactive map NBN species.nbnatlas.org/species/NHMSYS0021055637
Acknowledgements
This account would not have been possible without the shore work of David McKay and Simon Taylor and their help in supplying me with a live specimen to photograph. Sincere thanks are also due to Erling Svensen and James Lynott for the use of images of mating and ova; and, for comparison purposes, to Chris Rickard for photos and specimens of V. plicatilis and to David Fenwick for images of Capulus ungaricus.
Links and references
Forbes, E. & Hanley S. 1849-53. A history of the British mollusca and their shells. vol. 3 (1853), London, van Voorst. (As Velutina laevigata archive.org/stream/historyofbritish03forbe#page/346/mode/2up p346)
Fretter, V. and Graham, A. 1962. British prosobranch molluscs: their functional anatomy and ecology. London, Ray Society.
Fretter, V. and Graham, A. 1978. The prosobranch molluscs of Britain and Denmark. Part 6 – Cerithiacea, Strombacea, Hipponicacea, Calyptraeacea, Lamellariacea, Cypraeacea, Naticacea, Tonnacea, Heteropoda. J. Moll. Stud. Suppl. 9.
Graham, A. 1988. Prosobranch and pyramidellid gastropods. Linnean Synopsis No.2 (Second Edition). Leiden, Brill & Backhuys.
Hayward, P.J. & Ryland, J.S. (eds.) 1995 and reprints to 2009. Handbook of the marine fauna of North-West Europe. Oxford University Press.
Jeffreys, J.G. 1862-69. British conchology. vol. 4 (1867). London, van Voorst. (As Velutina laevigata archive.org/details/britishconcholog04jeffr/page/240 . Use slide at base of page to select pp 240 to 244.
McMillan, N.F. 1968. British shells. London, F. Warn.
Müller, O.F. 1776. Zoologiae Danicae prodromus : seu Animalium Daniae et Norvegiae indigenarum ; characteres, nomina, et synonyma imprimis popularium Original description, as Bulla velutina, item 2922 on p. 242.
www.biodiversitylibrary.org/item/47550#page/278/mode/1up
Telnes, K. accessed June 2019. The marine flora and fauna of Norway
www.seawater.no/fauna/mollusca/velutina.html [Subaquatic images of live specimens, including one with a white periostracum.]
Glossary
abapical = away from the apex of the shell.
adapical = towards the apex of the shell.
aperture = mouth of gastropod shell; outlet for head and foot.
cephalic = (adj.) of or on the head.
columella = solid or hollow axial “little column” around which gastropod shell spirals.
columellar = (adj.) of or near central axis of spiral gastropod.
columellar lip = lower (abapical) part of inner lip of aperture.
convolute shell = body whorl envelopes and conceals all earlier whorls including apex e.g. Trivia.
ctenidium = comb-like molluscan gill; usually an axis with a row of filaments either side.
distal = away from centre of body or from point of attachment.
ELWS = extreme low water spring tide (usually near March and September equinoxes).
height = (of gastropod shells) distance from apex of spire to base of aperture.
hispid = surface roughened by minute, stiff bristles.
hypobranchial gland = thickened, sometimes puckered, tissue on roof of mantle cavity of many gastropods. Secretes mucus to trap and consolidate particles from inhalant water. Often other biologically active compounds produced.
involute shell = body whorl envelopes and conceals all other whorls except earliest apical whorls which are recessed below the full height of the shell e.g. Retusa truncatula.
mantle = (a.k.a. pallium) sheet of tissue that secretes the shell and forms a cavity for the gill in most marine molluscs.
operculum = plate of horny conchiolin, rarely calcareous, used to close shell aperture.
osphradium (pl. osphradia) = organ for testing water quality (chemical and/or for particles) usually near approach of inhalant current to ctenidium.
palatal lip = outer lip of gastropod aperture.
pallium = (see mantle).
pallial = (adj.) of the pallium/mantle.
parietal lip/wall = upper part of inner side of gastropod aperture, often lacking clear lip structure with just a glaze on side of whorl adapically of columellar lip.
periostracum = thin horny layer of chitinous material often coating shells.
plankton = animals and plants that drift in pelagic zone (main body of water).
proboscis = internal feeding tube, containing the buccal mass with radula, that is only extended, often by inversion like a sock turned inside out, when feeding.
reflected = (of mantle edge) folded back over the rim of the shell’s aperture.
umbilicus = cavity up axis of some gastropods, open as a hole or chink on base of shell, often sealed over.
suture = groove or line where whorls of gastropod shell adjoin.
tumid = bulging, distended, distinctly convex.
veliger = shelled larva of marine gastropod or bivalve mollusc which swims by beating cilia of a velum (bilobed flap).