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Substrate: Watercolour paper 180gsm
Light sensitive anthotype dye: Paprika in water
Application: immersion + brush
Opaque layer: Eukalyptus leaves.
Exposure time: 2days intermittent sunlight.
I'm a big fan of the various species of the so called "ant plants"; plants which have developed symbiotic relationships with ants. In some species (such as the Myrmecodias and Hydnophytums) the plants produce highly modified stems which naturally develop hollow internal chambers which provide living spaces for ant colonies. The ants in turn benefit the plants by protecting their host from insect pests and providing nutrients derived from decomposing detritus from the ant colony. In addition to the previous examples there are a few members of the greater milkweed family which produce modified leaves which also provide sheltered sites for ants to establish their colonies. Some species, such as Dischidia pectinoides and D. major produce modified pouch-like leaves which serve as nesting sites. Other species produce large leaves which provide shallow, dome-like enclosures between the leaf and the substrate which can serve as a living site for ant colonies.
Hoya imbricata is one particularly attractive example of this last type of plant. It is an epiphytic plant with long, thin climbing stems which cling to tree trunks and branches, and bear very large succulent, plate-like leaves (reputedly measuring from about 2 inches, to nearly 10 inches in diameter in some varieties), which clasp the vertical surfaces upon which they grow. These leaves typically grow rather close together, slightly overlapping one another like roofing shingles or fish scales (the specific epithet "imbricata" alludes to this similarity to roofing tiles). Ants colonize the spaces beneath these leaves, often using adjacent leaves to serve as "nurseries", food storage and other specialized rooms or chambers for the ant colony. The spaces beneath the overlapping leaves may also serve as a protected highway, by which ants can travel from the ground to the upper branches of forest trees. This Hoya produces roots all along the length of the stems - those which are located just beneath the leaves will absorb nutrients from the detritus from the ant colony - providing the plant with a significant portion of its fertilization. The plant may also absorb a significant percentage of the carbon dioxide exhaled by the ants - providing the plant with vital carbon necessary in the production of sugars, proteins, and lipids.
Mature plants can grow many yards in length, and will branch and re-branch to produce intricate networks giving its host tree the appearance of being covered with shingles, or giant fish scales.
There are a number of varieties of this species in the wild, but the specific traits which distinguish the different varieties are not entirely clear to me - nor have I been able to find a listing of all of the recognized varieties in my research. Some varieties have closely spaced leaves which overlap, blanketing the trunks upon which they grow, while at least one variety is said to have long internodes with more widely spaced (non-overlapping) leaves. Most have comparatively small leaves (2 to 5 inches in diameter), while at least one variety produces leaves to about 10 inches across. In some, the leaves are of a uniform green coloration, but in others, the leaves are a dark green and are attractively marbled in pale greenish/grey tones. The leaf undersides of all varieties bear magenta to purplish pigments - which in many other plant species, is usually an adaptation to lower light levels - the purplish undersides to the leaf act as an accessory pigment to chlorophyll, which enables the plant to make use of additional wavelengths of light.
The flowers are produced in loose dangling umbels, which in my plant, measured to about 2 inches across. Larger, more mature plants will probably produce larger umbels with more flowers than this. The flowers are quite attractive, bearing "furry" greenish/cream colored petals. Other portions of the flower are of the same coloration, but are glossy and polished looking, earning them the common name for the genus, "Wax Flowers". While the flowers of other Hoya species can be highly fragrant, to my nose, the scent of this species is extremely faint: it is slightly sweet, with a trace of a musty under-tone. My plant has only flowered once: I am uncertain what combination of cooler temperatures, reduced light intensity, shorter daylight hours and less humid conditions may have helped initiate the formation of flower buds, but my plant flowered in November, about 2 months after I brought it indoors for the winter.
Hoya imbricata is not the easiest plant to maintain under typical household conditions. In my 19 months of growing this plant, I have struggled to discover which conditions best suits it: in summer, my plant usually produces a modest flush of growth, but it remains dormant through much of the other 9 months. It responds well to the increased light levels and higher temperatures of summer, especially when I move it into my unheated greenhouse in late spring. This species requires warm temperatures, bright but diffuse light, and quite humid conditions. Without high humidity, my plant languishes in a sort of persistent dormancy, and in winter, it has the tendency to loose moisture from its leaves and abort roots and young stems until humid conditions are restored. It is only when humidity exceeds about 60% that my plant even begins to show signs of growth: at levels closer to 90%, it seems to produce its most rapid growth. I am presently growing cuttings in a sealed 2 liter soda bottle with a soil-less mixture of peat moss and vermiculite watered with a weak solution of Miracle Gro fertilizer. This terrarium is kept just below two 40-watt fluorescent lights (the bulbs actually resting on the surface of the bottle). Because of the proximity of the lights, the temperature inside of the terrarium can rise to as much as 95 degrees Fahrenheit by day. At night (when the lights are off), temperatures typically fall to about 72 degrees. Conditions are very moist, so the sides of the container are perpetually drenched in condensation. This combination of warmth and moisture would rot practically any other plant, but my plant seems to thrive under these conditions, quickly responding with renewed, vigorous growth. After just a few weeks, one small cutting has produced 4 new stems, and the beginnings of at least 2 new leaves. Following this initial success, I started another cutting (a single leaf with several branching stems) under similar conditions. This cutting had been dormant for nearly one year - but within one week of this treatment, I observed the initiation of new growth at two nodes - probably the beginnings of two new vines; about a week later, it is producing the beginnings of new roots. Larger plants can be grown in a sort of mini greenhouse - I am growing my "main" plant horizontally in a long plastic storage container (the type designed for under-the-bed storage) with a pane of glass placed over the top to provide a more or less sealed environment (to ensure high humidity levels). I place fluorescent tubes on top of this (with the tubes resting just a few inches above the plant), and maintain light for approximately 14 hours a day. Even though I grow my plants on the basement floor (the coolest location in the house), temperatures inside of this container will rise to approximately 80 degrees by day, and cools to about 68 degrees at night (conditions which are probably a bit cooler than optimum). It would probably be best to place a 1 inch layer of very moist blend of Vermiculite/Perlite on the bottom of the container to provide adequate humidity, but any moisture retentive medium (such as peat-moss, or sterilized potting soil) will do.
In spite of the purple/magenta pigments on the underside of its leaves, (which is usually an adaptation to low light levels), Hoya imbricata seems to thrive when provided with bright but indirect light. When grown outdoors, bright dapple shade is probably best, but indoors, plants should be maintained just a few inches beneath fluorescent lights. Extended exposure to direct sunlight will tend to bleach and scorch its leaves.
Hoya imbricata requires a good support and a more or less solid surface upon which to grow in order to assure typical growth, otherwise the leaves of unsupported vines tend to roll in upon themselves (imagine a paper plate rolled into a cylinder). Cork-bark slabs, osmunda fiber slabs and posts, even long sections of logs and thick tree branches are good supports. For my own plant, I take two sections of black plastic mesh "gutter guards", and sew these along their sides and bottom to produce a long "sock". I fill this with an orchid potting mix consisting mostly of chipped coconut husk and cork bark. This mix retains moisture much better than cork-bark slabs, and may provide more humid conditions under the leaves than cork slab would alone. This support is rigid enough for the leaves to "clasp" normally, although I have found that it is best to wire new growth against it to assure good contact with the growing medium, at least until roots become established enough to hold the new leaves in place.
As with all Hoyas, this species requires warm temperatures to thrive: 80 to 90 degrees seems to be best, although it will tolerate higher temperatures than this: Extended periods of cooler temperatures (68 to 52 degrees) will tend to send plants into dormancy, and freezing temperatures will practically kill it instantly. While I have not tested its ultimate tolerances to cold, it will likely die if exposed to temperature in the 40's for any more than a few days, so if you do move your plants outdoors in summer, be prepared to bring it back indoors at the first predictions of cool weather.
It seems that only a few conservatories, and dedicated hobbyists grow Hoya imbricata here in the United States. Exceedingly few nurseries stock any of the varieties of this species, so it may sometimes be easier to acquire cuttings from other growers than it is to find in trade. My plant (Hoya imbricata var. basirotunda), for example, was originally acquired as cuttings generously provided by Myron Kimnach. The scarcity of this species in the trade is unfortunate, as this is an exceptionally interesting, and (in my humble opinion) one of the most attractive Hoya species that I know of. Perhaps its reputation as an "ant plant" works against it. While plants which are grown outdoors in the tropics and subtropics may sometimes become colonized by ants, it has been my experience that plants grown in more temperate climates do not attract ants, and can be grown without the presence of ants without ill effects. In nature such symbiotic relationships tend to be fairly specific, and usually involve a relatively few ant species; most ant species from northern latitudes would not colonize this plant. Grown indoors, particularly when grown in a more or less sealed environment, the chances of ants colonizing this species are virtually nil.
The specialized growing needs of Hoya imbricata will probably forever relegate this plant to dedicated growers only, particularly those from non-tropical climates. But for those growers who are not daunted by the challenges of providing year-round warm temperatures, high humidity and bright light, this species may very well be the plant for you. Its distinctive growth habit, attractive foliage (particularly those varieties with attractively marbled leaves), attractive "furry" flowers, and its fascinating adaptations to live symbiotically with ants will make it a standout in any collection. And it is unquestionably the most attractive "ant plant" which I have ever grown.
"Therapy"
Original Painting by Cara Buchalter of Octavine Illustration
Painted in gouache on Plywerk, a hand-crafted substrate wood board handmade in Portland, Oregon.
*The Inspiration*
My friend Dani is an art therapist. When looking at my work she always analyzes me, rather than my art. She pointedly asks, "What were you thinking when you drew this?" Or, "How does this image make you feel." I simply chuckle at her, smile and ignore telling her to stop shrinking my brain.
Her comment on this piece includes the psycho-babble that I love her for: "This is really a significant piece. I love the tension between the green and the diagonal red and wine colors. This piece must have come from deep in your subconscious..."
To be honest, I have no idea where my inspiration is derived from. Most of the time, I find a model--a photograph, magazine clipping or even a poem and start from there; my creativity a force unto itself.
For more information please visit my blog:
www.octavineillustration.blogspot.com
©2008 Cara Buchalter. Please don't take and use the images without permission, thanks.
The so called Tidal Zone (Piano Medio-litorale) is a zone where substrate is submerged for half of the time (hight tide) and emerged during the other half. Is the place where marine environments border with terrestrial ones, a place where life must face a continuous challenge, extreme changes in environmental parameters such as temperature, humidity, salinity. Consider for instance that during the winter the Bora wind may make temperature drop to -2°C, while during the summer rock surface may reach 50°C. This is the place where some animals live. Mollusca like Patella coerulea and Mytilus galloprovincialis, or Arthropoda like Pachygrapsus marmoratus (marbled rock crab).
Il piano medio litorale è la zona dove il substrato viene sommerso per metà del tempo (alta marea) ed è emerso per il restante tempo. E' il luogo in cui gli ambienti marini incontrano quelli terrestri, un luogo dove la vita deve affrontare una sfida continua, variazioni estreme dei parametri ambientali come temperatura, umidità, salinità. Si pensi per esempio che durante l'inverno il vento di Bora può portare la temperatura a -2°C, mentre durante l'estate la roccia può raggiungere i 50°C. Questo è l'ambiente in cui vivono Molluschi come Patella coerulea (tacapiera) e Mytilus galloprovincialis (pedocio) o Artropodi come Pachygrapsus marmoratus (granzo de scojo).
The beginnings of the giraffe sculpture. 44" tall. Styrofoam cut to shape and glued together.
#kimlarsonart
Family: Staphylinidae
Size: 3.3 mm (3.0 to 3.5 mm)
Origin: Holomediterran, Central Europe
Ecology: Especially in open biotopes, in rotting plant substrates
Location: Germany, Bavaria, Oberpfalz, Velburg
leg.det. U.Schmidt, 1.V.1984
Photo: U.Schmidt, 2017
Substrate: Quercus robur.
Eesti punase nimestiku liik, äärmiselt ohustatud (CR). LK II.
Rakvere, Lääne-Virumaa.
Seda seent ootasin täpselt 3 aastat. 2015 oli vana viljakeha, 2016 ja 2017 ei olnud üldse.
The fungus I was waiting to appear for three years.
Neuroscience Prof. Anil Seth argues that conscious human intelligence is tightly coupled to our living, biological substrate, not replicable or simulatable in silicon. Here are some of my reactions to his thought-provoking piece:
If human intelligence and consciousness is substrate dependent, as asserted, even down to individual neurons being irreplaceable by silicon substrates, then some precise and strong claims emerge: uploading human consciousness to a new substrate (as referenced in the article) would not be possible, and the BCI companies should not be able to augment the core of human intelligence. This would have profound implications on the possibility of “humanity” going along for the ride of exponential progress in AI.
(As an aside, it’s far more likely that our biology is left behind, and building an AI that exceeds human intelligence will likely happen before we fully understand the brains we have. It’s easier to build a new one than reverse engineer the complex product of an iterative algorithm like evolution, cortical pruning, or neural net development. The locus of learning shifts to the process, not the product of development.)
Let me lend further evidence to the article’s claim that neural complexity vastly exceeds the neural net abstractions of current AI, and that human intelligence may be substrate dependent. At the high level of the connectome, the average adult has 1000 input synapses to each neuron, and a newborn baby has 10,000. Silicon chips do not have enough metal layers to implement this level of fan-in per gate. And these connections are dynamic; 90% are pruned in childhood development, and neurons that fire together wire together in a dynamic and ongoing remapping over time. Pure, detailed biomimicry of the brain in mainstream CMOS silicon may be impossible, for now and the foreseeable future. Dynamic interconnect is the issue, and it may require a fully 3D, fluid, low power substrate. Like the brain. And it might take some of the special chemical properties of carbon to capture the richness (I wondered about this in 2005)
On the other end of the spectrum, the complexity of the neuron vastly exceeds a simple sigmoid voting circuit or digital gate abstraction. Ion channels activate like a bucket brigade down each synapse. HIV-like particles and endogenous cannabinoids may play a role in nearest neighbor interactions outside the synapse. The extra-cellular matrix, like the potting soil outside the neuron, relaxes in a long series of critical periods of childhood development, and under the influence of psychedelics, changing the neuroplasticity for interconnect changes. And the neuron types may be vastly more varied that the observable phenotypic buckets (pyramidal, mirror neurons, etc.). MIT’s Ed Boyden believes that the gene expression of each neuron is unique — literally billions of different neuron types.
But, even if human intelligence and consciousness are fully substrate dependent, it does not follow that human-level intelligence is impossible with a different substrate. We may have only one existence proof from biological evolution, but that does not imply exclusivity in the space of possibilities. The substrate of our brains is not very different from less intelligent animals; our unique advancement came from layering on more self-similar cortex — not a better substrate but more of it.
There is much of our substrate that is unique from its evolutionary origins and as a way to make the most of it – it’s quite a miracle that meat can think at all… and do math and compute, even if we choose not to. We can imagine a certain percentage of our substrate is for basic metabolic support and garbage collection and not fundamentally essential for the thinking at hand, when abstracted at the right level. It’s like the power supply implementation of a computer not being essential to the computation architecture itself. Some portion of the genetic code in each neuron is a vestigial passenger from viral transposons of the past.
It’s safe to say that some fraction of our substrate is critical to the architecture of intelligence, and the critical exercise of biomimicry is to figure out the right level of abstraction, the right level of detail, if we wish to follow a similar path in a different substrate.
The critique of current AI approaches as falling short with an over-simplistic simplification may be correct, but not insurmountable. Or the shortcomings could be a vestige of the architecture and process of training the LLMs of today. A number of the AI advances of the past decade were focused on Reinforcement Learning. It was Deep Mind’s initial focus. There has been a revival of late, with some like Yann LeCun arguing that LLMs will never get us there… but RL will. We have believed for many years that the future of AI compute will be analog in-memory compute, as implemented in Mythic chips, and the brain. Some believe it will require an embodied intelligence interacting with the world of physical AI. Jeff Hawkins is working on a memory prediction architecture arguing that the brain is not a computer at all (and perhaps the qualia of consciousness is the merely the retrospective sensemaking of predictions occurring continuously at all layers of the cortex). Perhaps we will need a coincidence detector for asynchronous circuits to mimic the fire-together/wire-together paradigm (perhaps with reversible-computing resonators). Perhaps a neurosymbolic hybrid will bear fruit in mimicking different brain regions distinctly. Perhaps we will need a series of critical periods, like human children, with a path dependence on the sequencing of neural net training. There are many possibilities and exciting work to come, a Cambrian explosion of sorts, exploring different abstractions of architecture and processes of training.
While we humans want to feel special, unique, and central to the future, it does not make it so. One day, we will have a more advanced non-human intelligence that is conscious. That will happen quite simply by considering the next million years of continued biological evolution, with a selection function that rewards intelligence. To argue otherwise is to argue that homo sapiens are somehow the endpoint of evolution. Evolution does not suddenly end, even if we wish it to. The biological substrate of our successor species will likely be similar to ours, as the primary vector of evolutionary progress operates most rapidly at the highest level of abstraction. The open question is whether non-biological evolutionary algorithms will usher in non-biological intelligence that is superhuman and conscious in a handful of years if we are pursuing the right level of abstraction for conscious intelligence or maybe decades if we need to explore radically different analogs to our analog meat minds.
— Anil Seth is the director of the Centre for Consciousness Science at the University of Sussex. Here is his article in Noema
Suggestions for the collection, examination and
photography of rock dwelling Patella species.
Ian F. Smith, April 2020
Casual photographs of the shell exterior of Patella species are unreliable evidence for differentiation and are likely to be declined as records by verifiers on iRecord, especially when they would alter the established distribution patterns. In north-west Europe, if a lateral view shows that a shell has a height 50%, or more, of its length, it can usually be accepted as Patella vulgata (but it often has a lower shell). Otherwise, the interior of a fresh shell may suffice but, often, a view of the foot and peripheral pallial tentacles is needed. This requires removal, without damage, of a live limpet from the substrate.
Collecting equipment
Dining knife with a strong, broadly rounded tip (sharp point risks damage).
Plastic box, lined with polythene, part-filled with seawater.
Collecting method
Please be sparing in how many you take, especially if limpets are not locally common.
Carefully approach a limpet in a pool or on damp rock; its shell will probably not be applied with full force to the substrate. Sudden movement or shadow may cause it to clamp down. When close enough, quickly force the knife, angled into the rock under the shell and foot. A horizontal thrust risks lethal damage. If the rock is soft, try to push the knife tip into its surface. Complete the removal by striking the handle of the knife with your free hand, as if hitting a chisel. If your first thrust fails to go under the limpet, abandon the effort as it will have clamped down and be impossible to move without damage. Try another one.
Place the removed limpet, sole down, in the lined box in water sufficiently deep to cover the shell; there should be air left in the box. Leave the box undisturbed for the limpet to settle and grip the polythene before transporting it. Upturned limpets are likely to die, so check as soon as home is reached that it is still upright. If collecting more than one, place each in a separate box as if one dies it will foul the water and kill its companions. If processing is delayed, keep in a refrigerator at about 7°C.
If you decide to examine/photograph the limpet on the beach you can dispense with the box. If replacing a limpet, it should be at the spot where found.
Examination equipment.
1. Container about 4 cm deep with base painted with black bituminous paint (or clear base on top of black polythene).
2. Piece of glass that will fit inside container.
3. Four identical flat supports about 15 mm thick (e.g. dissection blocks).
4. Sea water.
5. Spirit-levelled work surface. e.g. an aquarium stand with top of toughened glass such as door off old audio system cabinet. On the shore do your best to level the container.
Examination method.
Take the polythene with limpet out of its box and slide the limpet off it onto the glass.
Place the glass on the supports in the container with seawater deep enough to just cover the glass.
When limpet has gripped the glass, turn glass over and replace on supports. If the limpet moves to the edge you can usually slide it to the centre without it detaching.
The expanded foot will now be visible. When the limpet has settled down it will likely extend its head and you may see the mouth open, and the radula make feeding strokes. Eventually, the mantle will expand to the shell’s rim, and the peripheral pallial tentacles will extend and be visible against the black base of the container.
Compare what you see with images in the accounts at flic.kr/s/aHskokisge and flic.kr/s/aHskqnXPqt ; both contain comparative images of P. vulgata. Magnification and good lighting will help.
Photography
If the shell height is 50%, or more, of the shell length, an untilted side-image showing its profile is usually sufficient evidence for P. vulgata in north-west Europe. Otherwise, a clear photograph of the vacant shell interior may be enough. If foot and pallial tentacles are used for positive identification, a clear record photograph is needed for acceptance as personal judgement about what is opaque white or translucent is subjective, especially until the different species have been experienced. (From this cause I initially made mistaken records which had to be removed from NBN maps.)
Cameras vary widely in what they can do. A digital SLR with manual focus, rack and pinion tripod and two side flashes, as in the image above, is ideal but expensive. A separate sheet is available for Nikon 300s which may be of use with other DSLRs. This article is to guide you to general principles that I hope you will find useful with automatic compact cameras, mobile phone cameras etc, as well as DSLRs.
If about to buy a compact camera, one that is put to very good use by many is the Olympus Tough TG series shop.olympus.eu/en_GB/cameras/tough/tg-6 . It can withstand being dropped and can even be used submerged in a pool. It can be used by divers to moderate depths, but may have a short life if used without a camera housing. It has a 12 megapixel image sensor. Cameras with fewer pixels will take poorer images, those with more should do better.
Camera Handbook It is essential to read the handbook to learn how to use different features on your camera. Keep a note of what you find useful. Use the camera for general photography before attempting close ups.
Focusing
For zoomed-in close ups the depth of field of focus is tiny. If the subject and lens surface are not parallel, one part may be in focus and the rest blurred.
1) Avoid tilting the camera or the subject/base of container (unless both tilted at same angle) if possible. The most reliable method is with camera facing vertically down mounted on a rack and pinion tripod with both work surface and back of camera levelled horizontal with a spirit level.
2) Avoid the slightest movement of the camera as the automatic focus is unlikely to adjust quickly enough to minor movement. Use tripod as in 1; otherwise use whatever is available to steady the camera with lens surface parallel to subject/container base. One impromptu shore technique used by A. Rowat when photographing with an Olympus TG, is to hold it in two hands and project his little fingers to rest against the substrate. If the telescopic legs are withdrawn to their minimum, a tripod is very stable and can be stood on a table with the subject raised for closer focusing on a rigid box on the table.
3) Zoom in (closeness possible varies with camera) to fill as much of the frame as is possible with the subject so the automatic focus adjusts to the subject rather than a larger expanse of background.
4) Keep the subject as close as possible to the background which is likely to be what it focuses on when it is not possible to fill the frame with the subject. Holding the subject in one hand and the camera in the other while standing on the shore is likely to give a focused image of the shore and a blurred image of the subject and hand, added to by unavoidable small movement.
5) Use flash, as with it the lens aperture will close to the minimum for the bright light it provides. Small apertures give sharper images than large ones. Images taken in weak light will cause the aperture to open wide and the result is likely to be blurred, or very dark if it doesn’t open.
Glare and reflection
In the open, a horizontal water surface reflects the sky, including clouds. This hinders what can be seen in the water and gives photos a milky appearance. Ask a companion to block the sky by holding a black umbrella, or similar, high above the container or pool containing the subject.
Indoors, a flash located on the top of a camera pointing vertically down emits light at 90° to the water surface, and the light reflects directly back on the same track into the lens causing glare. If the camera can be operated with flash units off the camera, two should be placed, one at either side, at c. 45° tilt to the surface. Flash units can be free standing or mounted on a lens bracket protruding right and left. The light then is reflected away at 45° in the opposite direction, not into the camera. If a single side flash is used, one side will be brilliant and the other in black shadow. To avoid this if only one is available, put a reflector of crumpled aluminium foil close to the subject on the side away from the flash. But many cameras only have the option of single top-mounted flash. In this case, deviate slightly from focusing item ‘1’ (above) by tilting the camera and flash up a little. Experiment to find the minimum tilt that will get rid of reflection; you may find that when zoomed in very close that the small distance between lens and flash is sufficient for the reflection to miss the lens, even when the camera is untilted.
Damp/wet shells have a curved surface that reflects at an infinite number of different angles. However you position the camera or light source, some light will enter the lens and cause glare. To avoid this, either dry the shell or submerge it completely and photograph it as above. If part protrudes from the water, the curved meniscus at point of emergence will cause glare.
Exposure
The automatic exposure of a camera sets itself according to brightness of what it senses in the frame. If a small dark subject is surrounded by a large white background the aperture reduces to avoid what it senses, mainly the white background, from being too bright. This results in a correctly exposed background and an underexposed dull dark image of the subject. To avoid this, try photographing with a black smooth background, such as a base painted with black bituminous paint or a clear base resting on black polythene. Avoid textured surfaces as they catch and reflect light. Different camera models vary, so you may need to experiment.
Editing
An editing suite can vastly improve images. Photoshop is the best known, but is expensive and complicated to use. A simpler, cheaper one may be easier to master.
There may already be some editing facilities on your pc; it is worth having a look. I use PhotoStudio 6, but it is no longer available for official sale. Features I find most useful are crop, rotate, auto enhance, sharpen, brightness, saturation, contrast, fill, clone, brush, text, and stitch. Practice is required to get the best from editing.
24" substrate with 12" mirror I have covered in a mosaic of glass tile, stained glass, glass gems and tempered glass.
Lengths: 1) 11.6mm, 2) 12.1mm, 3) 13mm, 4) 13.2mm, 5) 14.2mm, 6) 12.1mm, 7) 13.9mm, 8) 12.2mm. Anteriors oriented upwards.
In Britain, sublittoral specimens usually grow up to 20mm long, 14mm wide, 10mm high, but 15mm is usual maximum length of intertidal specimens like these.
Full SPECIES DESCRIPTION BELOW
Key id. features: flic.kr/p/WNjbUS
APPENDIX re range advance/retreat: flic.kr/p/2jW74ig
Sets of OTHER SPECIES:
www.flickr.com/photos/56388191@N08/collections/
PDF version at www.researchgate.net/profile/Ian_Smith19/research
Testudinalia testudinalis (O.F. Müller , 1776).
Revised and Appendix added October 2020
Authors; Ian F. Smith (text) & Simon Taylor (shorework).
Current taxonomy: World Register of Marine Species (WoRMS)
www.marinespecies.org/aphia.php?p=taxdetails&id=234208
Synonyms: Patella testudinalis O.F Müller, 1776; Patella tessulata O.F Müller, 1776; Acmaea tessulata (O.F Müller, 1776); Acmaea testudinalis (O.F Müller, 1776); Collisella tessulata (O.F Müller, 1776); Lottia testudinalis (O.F Müller, 1776); Tectura tessulata (O.F Müller, 1776); Tectura testudinalis (O.F Müller, 1776); Testudinalia tessulata (O.F Müller, 1776);
Vernacular names: Northern tortoiseshell limpet (English); Brenigen fraith (Welsh); Schildkrötenschnecke (German); Skilpaddesnegl (Norwegian); Sköldpaddskålsnäcka (Swedish); Atlantic plate limpet (USA);
The former English vernacular was 'Common tortoiseshell limpet', but it is rare or absent in England so it was changed in October 2020 to 'Northern' on UK Species Inventory to reduce frequency of misidentification of Tectura virginea, the 'White tortoiseshell limpet' as Testudinalia testudinalis.
GLOSSARY below.
Shell Description
In Britain, sublittoral specimens usually up to 20mm long, 14mm wide, 10mm high, but 15mm is usual maximum length of intertidal specimens 1Tt flic.kr/p/WadzLk & 2Tt flic.kr/p/WNjbUS . Extreme maximum length 30mm in Britain; may be larger in USA (Jeffreys, 1865). Shell rather thin and easily damaged when prising a specimen off substrate. Usually a low conoid, shell height about 25% to 36% of length 3Tt flic.kr/p/X8KE25 . Eccentric apex tilted forwards, varies about 25% to 40% of shell-length from anterior. Minute spiral coil shell of veliger larva survives on apex until shell 1mm long. Aperture rim an ellipse; posterior and anterior usually similar breadth 4Tt flic.kr/p/XbymyT .
Anterior profile almost flat with small shallow concavity that diminishes when adjacent tilted apex is eroded; posterior profile flat to slightly convex 3Tt flic.kr/p/X8KE25 . Superficially smooth, but major growth lines, and many finer ones, run concentrically around the shell 5Tt flic.kr/p/XoDw7c ; spacing between them is closer on the anterior as growth is more rapid at the posterior. Consequently, the lines, seen from the side, have a downward tilt towards the anterior 6Tt flic.kr/p/X8KABj Many fine ridges radiate from the apex, though they are often eroded near it. The visibility of the radiating lines and growth lines of an individual shell varies with the viewing conditions, and they may be eroded from some or most of a shell 7Tt flic.kr/p/X8KAeL . Shell matt, opaque or slightly translucent. External ground colour of live, clean shell lacking epizoic growths is whitish; sometimes slightly darkened or greenish if shell translucent enough to transmit colour of shell interior or mantle 8Tt flic.kr/p/WCkgDH . Brown and blackish brown marks radiate from the apex, bifurcating and reuniting to form a reticulated pattern that may be a wide open net with the white ground colour dominant 9Tt flic.kr/p/WMzPt9 , but, very often, brown predominates forming a tessellation of approximately rectangular, brown marks 10Tt flic.kr/p/X8KwDE which may merge to create a generally brown shell 11Tt flic.kr/p/X8KuKE . Shell may be colourless transparent showing the green mantle and dark shell interior, occasionally on adults 12Tt flic.kr/p/XfRgGQ and frequently on small juveniles 13Tt flic.kr/p/WCkfdX . Shell colour of live specimens may be affected by closely adhering thin coating of brown or green algae 14Tt flic.kr/p/X8Kt81 . Colours are less bright on dry shells, but, usually, growth lines are more distinct. Internally, shell 4Tt flic.kr/p/XbymyT has 1) an aperture rim coloured as exterior; secreted by the yellow to mustard brown mantle-edge 15Tt flic.kr/p/X8KpLb , 2) a wide, matt white, peripheral zone 16Tt flic.kr/p/XoDmd4 ; secreted by the green mantle-skirt, 3) a very thin, whitish mantle-attachment scar 17Tt flic.kr/p/X8KpZN , most distinct at the anterior where it is not flanked by 4) the narrow, glossy, white U-shape pedal-retractor muscle scar, 5) an amphora shaped, chocolate brown area enclosed by scars 3 & 4; secreted by green mantle over visceral hump and 6) a cream/orange/pale brown patch at the vertex.
Body description
Main colour of flesh is white or yellowish white 18Tt flic.kr/p/Wadmi8 . Head has short stout snout with a large mouth. Large,extendible, outer lips have a gap ventrally which can be held closed or open 19Tt flic.kr/p/WNjiGE . The lips can be held in a variety of positions, sometimes resembling a large snout 20Tt flic.kr/p/XpnWWD & 21Tt flic.kr/p/Xksgvu . The lips are thin and flimsy when extended, but are reinforced internally by longitudinal ribs that, when held together, give the lips a wavy edge 19Tt flic.kr/p/WNjiGE . A pink, internal odontophore can be seen through the translucent, white head 19Tt flic.kr/p/WNjiGE & 18Tt flic.kr/p/Wadmi8 . The odontophore is separated from the outer lips by the yellowish inner lips that open laterally and close to a vertical line . When they open, the radula with rust-coloured iron rich teeth is protruded. The long, slender, white, unpigmented cephalic tentacles are up to 70% of shell length when fully extended 20Tt flic.kr/p/XpnWWD . The tiny eye on the base of each tentacle dorsally is a deep, narrow pit, detectable in the translucent tentacle as a black line running in to a broader black spot 18Tt flic.kr/p/Wadmi8 . When viewed ventrally through the tentacle, the broad internal spot is faintly discernible 19Tt flic.kr/p/WNjiGE . Some or all of the black may be pigmented retinal cells. The eye can probably differentiate light from shade, and detect the direction of the light source, but cannot discern shapes. The mantle is translucent and colourless but usually covered with a dense layer of removable pigment; emerald green apart from a peripheral mustard brown border 15Tt flic.kr/p/X8KpLb . When viewed ventrally on a live specimen, only the mantle skirt is visible and the colours are affected by the adjacent shell interior and by being seen through the mantle, so the emerald green pigment often looks blue-green, and the periphery shows the dark shell through translucent white 17Tt flic.kr/p/X8KpZN . The mantle skirt contains the peripheral efferent pallial vessel 22Tt flic.kr/p/XpnWLZ and is fringed with translucent, white pallial tentacles 23Tt flic.kr/p/Xksgfj . The mantle cavity consists of a nuchal cavity over the head, and a wide pallial groove around the entire periphery of the foot-head. Unlike patellid limpets, it has no pallial gills in the pallial groove, but does have a large, extendible, bipectinate ctenidium attached to the left of the nuchal cavity that, when extended, projects from the right of the nuchal cavity 24Tt flic.kr/p/XpnWp6 & 25Tt flic.kr/p/XksfKb . The lamellae on the right of the ctenidium are large, but those on the left are small and often hidden from view, so the ctenidium may appear monopectinate. The pedal-retractor muscle, a U of white muscle bundles separated by narrow gaps, attaches the body/foot to the shell 26Tt flic.kr/p/XpnW7c & 18Tt flic.kr/p/Wadmi8 . Sole and sides of foot white or pale yellowish white. Sole approximately circular when fully spread 22Tt flic.kr/p/XpnWLZ . Sides of foot lack features such as epipodial tentacles. When crawling, usually only the extended pallial tentacles, cephalic tentacles and, occasionally, the ctenidium protrude beyond the shelter of the shell 23Tt flic.kr/p/Xksgfj . No penis as fertilization is external.
Internal functional anatomy
Blood circulation and respiration
Image links: 22Tt flic.kr/p/XpnWLZ , 24Tt flic.kr/p/XpnWp6 , 25Tt flic.kr/p/XksfKb .
Small vessels carry oxygen-depleted, colourless blood from the visceral mass through gaps between the muscle bundles of the pedal retractor muscle (24Tt ) and through the green mantle skirt (22Tt ) to the efferent pallial vessel.
The large, peripheral, efferent pallial vessel (22Tt & 24Tt ) carries oxygen-depleted blood round the entire animal between zones 1 & 2 of the mantle skirt.
Blood in the efferent pallial vessel travels forwards on both sides, that on the right passes round in front of the head to the left where two vessels (22Tt) carry the blood into the nuchal cavity where it passes through the ctenidium (24Tt ) to be oxygenated and then recirculated to the body.
The green ctenidium is attached within the left of the nuchal cavity . When the limpet is in motion, the ctenidium protrudes from the right of the cavity(24Tt) and may extend beyond the rim of the shell. At rest, it often contracts 50% and is concealed within the cavity. It consists of a substantial axis (24Tt & 25Tt ) with many lamellae (24Tt & 25Tt) resembling the teeth of a comb attached to each side; bipectinate arrangement. The lamellae on the right of the axis are large (24Tt & 25Tt), but those on the left are small (25Tt), restricted to the distal part of the axis, and often hidden from view so the ctenidium may appear monopectinate 24Tt.
The inhalant current of oxygen-bearing seawater enters the nuchal cavity from the left 26Tt flic.kr/p/XpnW7c and passes between the lamellae which absorb the oxygen for blood flowing through them. The oxygenated blood flows into the large branchial efferent vessel (24Tt & 25Tt) in the axis and thence to the heart (25Tt) near the base of the ctenidium to be recirculated through the body. Exhalant water currents pass along the pallial groove on either side of the body to exit at the mid-point of the posterior 26Tt flic.kr/p/XpnW7c .
Alimentary and excretory features .
The inner lips of the mouth, described above, open into the buccal cavity. Dissection shows that the anterior wall of the cavity is reinforced by a pliable, white, chitinous, antero-dorsal plate, called the “jaw” though it is not articulated and does not bite 27Tt flic.kr/p/Xksf1q . It serves as an attachment for several muscles and has two lateral wings that meet dorsally at an angle and form an anterior shield for the inner lips when they are open. Within the buccal cavity there is a large pink odontophore 27Tt flic.kr/p/Xksf1q consisting of a right and left bolster which is covered in thick cuticle. Much of the bolsters is made of strong cartilage-like material.
The anterior of the radula, widened into a hyaline shield, rests on the dorsum of the odontophore and is recessed slightly into the groove between the bolsters 27Tt flic.kr/p/Xksf1q . The strong, iron-impregnated, unarticulated teeth are firmly fixed in a backwardly inclined position on the radula, but the anterior tip of the radula bends over the front of the odontophore so that the front row of four teeth are inclined forwards like a chisel 27Tt flic.kr/p/Xksf1q . To feed, the strong muscles of the odontophore thrust it forwards against the front of the buccal cavity which, reinforced by the jaw, restrains the odontophore but allows the front teeth to project strongly from the narrow vertex of the gap between the wings of the jaw. When applied to the substrate, the teeth easily loosen diatoms, algae and other growths coating bedrock and boulders, and the curve of the withdrawing teeth acts as a scoop to lift particles back to the oesophagus in the buccal cavity. The action is surrounded by the outer lips which prevent the escape of loosened food fragments. Marks left by the front four teeth on the printed surface of a polythene sheet show that specimens with shells c. 14mm long make straight thrusts of about 0.5mm at each stroke 28Tt flic.kr/p/XpnVJD . Like other limpets and some sea snails that graze rock surfaces, T. testudinalis has a radula considerably longer than its shell 29Tt flic.kr/p/XkseKq which requires several folds to fit it inside its body 30Tt flic.kr/p/XpnUSP . The cause of the correlation between length and rock grazing is uncertain. It may be that a lengthy process is needed for the teeth to acquire the required hardening mineralization. Tooth creation starts at the slightly bifid, white, inner end of the long radular sac 31Tt flic.kr/p/XksdD7 with secretion of colourless transparent cuticular material by odontoblast cells. As each new tooth commences, the previous one is pushed forwards along the sac. Cells along the roof of the sac make incremental additions, including the hardening salts of iron and silicon, to the teeth as they travel along the sac, with a progressive change from colourless through darkening shades of yellow/orange visible through the translucent sac walls. Creation is complete by the time the tooth reaches the buccal cavity, where it emerges from the radular sac onto the odontophore in front of the opening of the oesophagus.
A whitish salivary duct runs next to each of the two dorsal folds of the oesophagus 32Tt flic.kr/p/XpnUP2 . The ducts carry mucus from the salivary gland to the buccal cavity to lubricate the feeding process and bind the food particles brought in by the radula. The mucus does not have a digestive function. In the rear of the buccal cavity, the mucus-bound food particles pass into the entrance of the oesophagus 32Tt flic.kr/p/XpnUP2 and the radula passes into the radular sac directly below the oesophagus (so now out of sight in dorsal view, except for a short section usually visible at the surface of the digestive gland 33Tt flic.kr/p/Xksdxf ). Lubricating mucus is provided to the oesophagus by the oesophageal gland consisting of a series of tubules on either side of it 32Tt flic.kr/p/XpnUP2 . The oesophagus passes into the visceral mass. Food is moved along it by cilia to where it widens to become the stomach. The digestive gland 33Tt flic.kr/p/Xksdxf , composed of a mass of tubules and usually the most obvious organ on the surface of the visceral mass when the shell is removed, opens into the stomach through a duct. Digestive cells in the tubules ingest particulate food to digest it intracellularly (Fretter & Graham, 1994, p. 219). The tubules extend into the blood filling the haemocoel, and their very thin covering of connective tissue allows the passage of nutrients into the blood. Undigested material passes into the long coiled intestine 33Tt flic.kr/p/Xksdxf where it is compressed and bound with mucus 28Tt flic.kr/p/XpnVJD to prevent fouling of the ctenidium. The faecal string passes through the rectum 33Tt flic.kr/p/Xksdxf to emerge from the anus at the rear right of the nuchal cavity and, with particulate matter removed by cilia from the inhalant water, is conveyed along the pallial groove by cilia, helped by the flow of exhalant water, to be expelled from the mid-point of the posterior of the shell 26Tt flic.kr/p/XpnW7c . The large right nephridium ( kidney) is attached to the inner surface of the mantle 34Tt flic.kr/p/WNje2h , but often difficult to distinguish when it is the same colour as the viscera below it 33Tt flic.kr/p/Xksdxf . The right nephridium extends round onto the left of the animal. The nephridipores (openings) of it and the smaller, unobtrusive, left nephridium are sometimes visible 34Tt flic.kr/p/WNje2h on either side of the anus . Their urogenital products are conducted to the posterior of the animal by cilia and the exhalant water current.
Reproductive organs
The gonads are situated between the viscera and foot. Just before and during breeding, they may spread over much of the viscera, but they are usually hidden, apart from a small section, on an animal removed from the shell. If the mantle is taken off a female, her ovaries may rapidly expand as the ova absorb water and the constraint of the mantle is removed 35Tt flic.kr/p/XpnUtT . Female ovaries are granular, and individual red/brown ova readily break away 36Tt flic.kr/p/WNjcRm . Male testes have numerous interconnected tubules 37Tt flic.kr/p/W8wFmq . Male and female gonads have similar orange-brown colours, or pink (Fox, 2003), with individual variation of shade which may change with breeding condition. Fertilization is external, so the male has no penis. Gametes leave both sexes through the right nephridium (kidney) via its nephridipore 34Tt flic.kr/p/WNje2h close to the anus in the nuchal cavity. The female also exudes a thin mucous film that secures the ova to the substrate.
Key identification features
Testudinalia testudinalis
1: Maximum length usually 20mm, occasionally 25mm, rarely 30mm.
2: Shell exterior matt-whitish with radiating chocolate-brown rays that often bifurcate and reunite across the shell 1Tt flic.kr/p/WadzLk .
3: Shell interior porcelaneous-white with brown-banded peripheral border, an amphora-shaped, chocolate-brown patch and a pale vertex patch 4Tt flic.kr/p/XbymyT .
4: No prominent sculpture (except sometimes irregular repair-line of damage), but many fine concentric growth lines and radiating striae 5Tt flic.kr/p/XoDw7c .
5: Mantle skirt with emerald green pigment dorsally that looks blue-green when viewed ventrally 17Tt flic.kr/p/X8KpZN .
6: Large pallial tentacles protrude beyond shell perimeter when active 23Tt flic.kr/p/Xksgfj .
7: Northern species stretching south to southern Scotland, northern Ireland, Isle of Man, south-west Sweden and Rhode Island, USA.
8: Sometimes, but more often not, on pink, calcareous, encrusting algae with no pale feeding pits, and faecal rods with flat truncated ends that are not chalk-white.
Similar species
Tectura virginea
The only ‘tortoiseshell limpet’ in the southern half of Britain where it is often mis-recorded as Testudinalia testudinalis.
1: Maximum length 12mm.
2: Shell exterior whitish/yellowish/bluish with radiating pinkish rays and/or light-brown chains which are often mistaken for brown marks of T. testudinalis, especially small juveniles 42Tt flic.kr/p/XASHRd .
3: Shell interior white often translucent showing exterior marks, sometimes red-brown V near vertex 43Tt flic.kr/p/WCkdUp .
4: Sculpture of slight threadlike radiating striae 43Tt flic.kr/p/WCkdUp , often indistinct or absent 44Tt flic.kr/p/XASHz1 , and numerous fine concentric growth lines
5: Mantle-skirt white, yellowish, or blue-green with reddish bands on periphery 45Tt flic.kr/p/XfRfyN , 46Tt flic.kr/p/WA5eV5 and 47Tt flic.kr/p/XASHvo .
6: Outer edge of mantle has many small, unobtrusive, translucent processes and many large white repugnatorial glands pointing inwards from mantle edge, but no prominent outward pointing pallial tentacles 48Tt flic.kr/p/XRRcsx .
7: All round Britain except Liverpool Bay and parts of SE England.
8: Nearly always on pink, calcareous, encrusting algae with pale feeding pits and short, chalk-white faecal rods with hemispherical ends.
Habits and ecology
T. testudinalisoccurs on rocky shores at MLWST, or MHWNT in pools, and to 50m depth. It feeds on diatoms and algae 12Tt flic.kr/p/XfRgGQ coating bedrock and boulders. Eulittoral specimens are often found stationary on bare vertical 38Tt flic.kr/p/XASJfQ or overhanging 39Tt flic.kr/p/WCkeDv surfaces during daylight hours. Fretter and Graham (1962) say it and Tectura virginea feed on encrusting algae but, though T. virginea is usually found on/near it, only 18 of 300 images of T. testudinalis on iNaturalist show encrusting algae. Lord (2008) showed that immersed laboratory specimens fed nocturnally on alga-encrusted rocks but in daylight moved onto bare vertical rocks, where they remained stationary. A homing instinct, if any, is weakly developed in this species, so a home scar is not engraved into soft rock (Lord, 2008).
Defence: the simple eyes 18Tt flic.kr/p/Wadmi8 may be able to detect the shadow of an attacker, but the principal warning organs are probably the touch-sensitive, long cephalic tentacles, plentiful encircling pallial tentacles 23Tt flic.kr/p/Xksgfj and large outer lips 20Tt flic.kr/p/XpnWWD. The white and brown tessellated shell is probably cryptic on the bare rocks favoured in daylight 8Tt flic.kr/p/WCkgDH. Predators include gulls, crabs and starfish. When threatened by a starfish, it exhibits, like small Patella vulgata, a flight response (Lord, 2008).
T. testudinalis breeds in spring and early summer (April to July in New England). Gonochoristic; the male lacks a penis, but he mounts a female's shell, sometimes for several hours in expectation, to be proximate when she spawns so he can release his sperm to be drawn in by her inhalent current as the eggs emerge 40Tt flic.kr/p/W8wF1A. In a refrigerator maintained at about 8ºC, some of a group of eight individuals, collected in late May, bred in June producing a thin film of mucus with the ova widely spaced and attached to it (pers. obs.). The film was only loosely attached to the smooth base of the container, but adhesion would probably be better on a rough surface. The eggs hatched by late June as free trochophore larvae (stage passed within egg by most less “primitive” spp.) but further development failed. In the wild, after a short time in the plankton, the trochophores metamorphose into veligers and, after further growth in the plankton, settle and assume limpet form by August with a thin, translucent, 2 mm long shell 13Tt flic.kr/p/WCkfdX .
Distribution and status
T. testudinalis is a cold-water, northern species in Arctic Canada, Greenland, Iceland and northern Russia, which extends south to Rhode Island (USA), Britain, Ireland, southern Scandinavia and the German Baltic, but not the brackish inner Baltic. In the relatively cold 19th century is extended its range southwards in Britain, Ireland and probably elsewhere, except the Baltic and Gulf of St Lawrence where low salinity probably prevented its spread. In the late 20th century and early 21st century, when temperatures rose markedly at an increasing rate, its distribution seems to have fallen back northwards to about its pre-spread positions.
The appendix at flic.kr/p/2jW74ig describes in detail the distribution limits at different dates.
Acknowledgements
I am indebted to Simon Taylor and David W. McKay for providing me with specimens for photography and study. The account would not have been possible without their help. I thank Dr Paula Lightfoot and Becky Hitchin for generously providing images and information. The much valued advice of Dr Julia Sigwart and Dr Lauren Sumner-Rooney is gratefully acknowledged. Many thanks also to Inga Williamson for shore work related to the account.
A separate acknowledgement is made after the Appendix at flic.kr/p/2jW74ig of those who contributed to its creation.
Links and references
Forbes, E. & Hanley S. 1849-53. A history of the British mollusca and their shells. vol. 2 (1849), London, van Voorst. (As Acmaea testudinalis; Free PDF at archive.org/stream/historyofbritish02forb#page/434/mode/2up Use slide at base of page to select pp.434-437.)
Fox, R. 2003. Invertebrate Anatomy On Line; Tectura testudinalis
lanwebs.lander.edu/faculty/rsfox/invertebrates/tectura.html
Fretter, V. and Graham, A. 1962. British prosobranch molluscs. London, Ray Society.
GBIF (Global Biodiversity Information Facility). Distribution map for T. testudinalis accessed October 2020. Includes many obvious errors such as far-inland or tropical locations. www.gbif.org/species/4369953
Graham, A. 1988. Prosobranch and pyramidellid gastropods. London.
Hargreaves, J. A. 1910. The marine mollusca of the Yorkshire coast and the Dogger Bank. J. Conch., Lond. 13: 80 – 105.
iNaturalist map and images of T. testudinalis records (accessed October 2020) www.inaturalist.org/taxa/415169-Testudinalia-testudinalis
Jeffreys, J.G. 1862-69. British conchology. vol. 3 (1865). London, van Voorst. (As Tectura testudunalis; Free PDF at archive.org/stream/britishconcholog03jeff#page/246/mode/2up . Use slide at base of page to select pp.246- 248.
Lebour, M.V. 1902. Marine mollusca of Sandsend. The Naturalist.
Lord, J. 2008. Movement patterns and feeding behaviour of the limpet Tectura testudinalis (Müller) along the mid-Maine Coast Honors Theses. Paper 243. digitalcommons.colby.edu/honorstheses/243
Lumb, F.E. 1961. Seasonal variation of the sea surface temperature in coastal waters of the British Isles. Scientific paper no. 6. London, HMSO.
pdf at digital.nmla.metoffice.gov.uk/file/sdb%3AdigitalFile%7Cc2...
McMahon, R. F. & Russell-Hunter, W. D. 1977. Temperature relations of aerial and aquatic respiration in six littoral snails in relation to their vertical zonation. Biol. Bull. 152: 182 to198.
Publication info: Woods Hole, Mass. :Marine Biological Laboratory,
View at www.biodiversitylibrary.org/page/1540015#page/202/mode/1up
whole bulletin is 38 MB, but page has option to create 5MB pdf of just the article by selecting pp 182 to 198
www.biodiversitylibrary.org/pdf4/066873200017332.pdf
Mieszkowska, N., Leaper, R., Moore, P., Kendall, M.A., Burrows, M.T, Lear, D., Poloczanska, E., Hiscock, K., Moschella, P.S., Thompson,R.C., Herbert, R.J., Laffoley, D., Baxter, J., Southward, A.J., & Hawkins, S.J. 2005. Assessing and predicting the influence of climatic change using eulittoral rocky shore biota. M.B.A. Occasional publication No. 20.
www.researchgate.net/publication/281164392_Assessing_and_...
Parker, D.E., T.P. Legg, and C.K. Folland. 1992. A new daily Central England Temperature Series, 1772-1991. Int. J. Clim., Vol 12, pp 317-342 www.metoffice.gov.uk/hadobs/hadcet/ [includes update to 2020].
Walker, C.G. 1966. Studies on the jaw, digestive system, and coelomic derivatives in representatives of the genus Acmaea. In Abbot, D.P. et al (ed.). 1968. The biology of Acmaea. Veliger 11: supplement. 88 to 97.
pdf at archive.org/details/veliger111968berk
Yonge, C.M. and Thompson, T.E. 1976. Living marine molluscs. London.
Current taxonomy: World Register of Marine Species (WoRMS)
www.marinespecies.org/aphia.php?p=taxdetails&id=234208
GLOSSARY
afferent = (adj. of vessel) carrying blood etc. towards an organ.
aperture = mouth of gastropod shell; outlet for head and foot.
auricle = part of heart that receives blood from the adjacent ctenidium.
bipectinate = (See ctenidium.)
cartilages = (in gastropods) structures of tough, resilient material, histologically resembling vertebrate cartilage, embedded in tough connective tissue of left and right bolsters of the odontophore. Support and maintain shape of odontophore, and provide attachment for muscles controlling its movement.
cephalic = (adj.) of or on the head.
coll. = in the collection of (named person or institution; compare with leg.).
comminuted = reduced to minute particles or fragments.
ctenidium = comb-like molluscan gill; usually an axis with a row of filaments/lamellae on either side (bipectinate), sometimes on one side only (monopectinate).
efferent = (adj. of vessel) carrying blood etc. away from an organ.
ELWS = extreme low water spring tide (usually near March and September equinoxes).
emersed = not covered in water.
epipodial = (adj.) of the epipodium (collar or circlet running round sides of foot of some gastropods).
gonochor(ist)ic = (syn. dioecious) having separate male and female individuals, not hermaphrodite.
growth line = line, transverse to direction of shell increase, indicating aperture's rim position during a pause in growth. Seasonal pauses create more major lines than shorter pauses such as diurnal ones.
haemocoel = blood-filled body cavity of gastropods. (Molluscs have an “open circulatory system” which includes large cavities with sluggishly moving blood that directly bathes organs.)
immersed = covered in water.
intracellularly = occurring within a cell or cells.
lamellae (of ctenidium) = plate like leaflets/filaments arranged like teeth of a comb.
leg. (abbreviation of legit) = 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.
monopectinate = (See ctenidium.)
MLWS = mean low water spring tide level (mean level reached by lowest low tides for a few days every fortnight; Laminaria or Coralline zone on rocky coasts).
nephridium (pl. nephridia) = cilia-lined excretory/osmoregulatory tubule (kidney).
nephridiopore = opening of nephridium (kidney) for excretion. a.k.a. nephropore, or renal pore.
nuchal cavity = cavity roofed by mantle that contains head of limpet; part of mantle cavity (remainder consists of pallial groove on each side of body).
pericardium= sac containing the heart.
periostracum = thin horny layer of chitinous material often coating shells.
protandrous hermaphrodite = sequential hermaphrodite with individuals starting as males and later changing to female.
trochophore = spherical or pear-shaped larva that swims with aid of girdle of cilia. Stage preceding veliger, passed within gastropod egg in most spp. but free in plankton for patellid limpets, most Trochidae and Tricolia pullus.
veliger = shelled larva of marine gastropod or bivalve mollusc which swims by beating cilia of a velum (bilobed flap).
ventricle = contractile part of heart that pumps blood.