I recently illustrated The Hidden Universe by Alexandre Antonelli.  This image of the zonation of a rocky shore ecosystem was one of the illustrations.

The timing of this illustration was an extraordinary stroke of luck.  Alex wanted a drawing that shows the different animals and seaweeds on rocky shores.  These plants and animals grow in different zones going up the shoreline.  The factors that cause these differences (also known as zonation) include physical forces such as salt levels, dehydration, physical damage from the waves.  There are also biological, or biotic factors at play, such as predation, competition for food, and competition for space.

How do I know?  Well, the week I started this project, I went on a fabulous weekend course.  All about Discovering life on rocky shores!  The course is hands on, so I took tons of photos and copious notes.  I sketched barnacle speciation, and shrieked with delight at Porcelain crabs.  I even saw my first blue-ray limpet.

My very poor photo of Blue-ray limpets

So when this illustration turned up, I was exceptionally well equipped.  Here’s the pencil rough, which I annotated so that it made a bit more sense.

Annotated rocky shores illustration

And here’s the final illustration.  Inking it up was an absolute joy, although it took a great deal longer than I would have liked!

Rocky shore line ecosystem zonation of species

In this blog, there are so many animals and plants discussed, that I’m taking the decision not to give every scientific name.  It’s just be a jumble of italicised Latin if I did. Apologies in advance to the purists among you!

Rocky shores: Splash zone

The very top of a shore is known as the splash zone.

Sea plantain Plantago maritima

The top zone has very little growing there except for the odd brave plant and Xanthora lichen.  you might get tough periwinkles, but the combination of dry and salty splashing is lethal to most organisms.

Plants that do survive here have amazing adaptations to allow them to tackle the salt.  They’re known as Halophytes, and I wrote a blog on them a while back.

Animal wise, shore flies visit, and slaters (relatives of woodlice) crawl about.  You get limpets, clinging on and anchoring themselves to the exact same spot for most of their lives.

Thrift Armeria maritima

Rocky shore Intertidal zone

Lower down, you’ve got the high tide or intertidal zone.  Animals and plants living here have to handle massive fluctuations in temperature and being out of water for 12 plus hours every day.  the crashing waves cause physical damage.  On the plus side, it’s so hard to survive here that there’s not a lot of competition.

Limpet (with mating barnacles on the side)

Chitons, whelks, winkles, and barnacles live here alongside hardy sea anemones and the toughest of all seaweeds, channelled wrack.

The whelks travel around when the tide is in, predating on mussels and other bivalves by drilling a hole through their shells and sucking out the meat.

Detail of the intertidal showing chitons, whelks, and a sea anemone

Rocky shore Mid tidal

This stretch is exposed for shorter times between tides.  There’s less wave action as a lot of the time the area is submerged.  You need to handle the changes in temperature and salt, but it’s a less extreme environment than the upper tidal or splash zone.

Mid tidal zone: Crab and Breadcrumb sponge with coral weed

More animals and plants live here.  Tons of shells like top-shells, barnacles, Perwinkles, and mussels, hang out amidst the seaweeds.   Different species of top shell and winkle favour different areas of the rocky shore.

Topshell

You can tell Periwinkle and Top-shell species apart by the shape of their operculum, the door at the bottom of their shells.  In top-shells this is invariably round.  Periwinkle operculum are tear shaped.

Detail of the mid tidal: Smooth periwinkle, Pin cushion starfish, mussels and bladderwrack

There are more sea anemones, and visiting shore crabs.  Sponges and starfish abound.

The drawback is that there are more animals surviving here, so there’s more competition for space.  Predation kicks in too, with the starfish feeding on mussels, flat periwinkles chewing seaweeds, and whelks feeding on bi-vales.  These are the biotic factors starting to kick in.

If space does become free, it’ll quickly be re-colonised.

Rocky shore Mid tidal: Barnacles

Barnacles have a good system; they can grow on top of other shellfish, and can extend their filtering arms from this substrate.  Barnacles are actually crustaceans, related to crabs and shrimp.

Free living barnacle larva land on intertidal rocks where their heads split and they establish themselves for a stationary life.  They filter food particles form the sea with their legs, which are adapted to work as sieves.

The problem with living on a shellfish is that if and when that shell dies, you get plunged to the floor where it’s every likely you will die.

Blue mussels Mytilus edulis with barnacles and bladder wrack

Rocky shore Mid tidal: Seaweeds

Seaweeds thriving in the mid-tidal zone are bladder-wrack, egg-wrack, toothed wrack, spiral wrack.  These grow at very specific heights along the shore, depending on their adaptations and tolerance to heat and dry conditions.

Bladderwrack Fucus versicolor

Rocky shore Lower tidal zone: Species

The lower tidal zone is altogether more comfortable.  Exposure to air, desiccation and the heat of the sun is far less frequent.  In fact, it only happens at low tides.  The waves are less problematic.

The bladder wracks give way to kelp.  Brown algal wracks are unpalatable to most animals.  In the UK, it’s only the Flat periwinkle that can handle eating it.  Oar weed and sugar kelp are an entirely different prospect and are clearly much easier to eat.  If you are lucky and look closely at low tide, you might see the tiny and stunning Blue-ray limpets grazing on a blade of Oar weed.

Edible crab, sea urchins, tube worms, star fish, brittle stars, more sea anemones, sea lemons and nudibranch hang out here, along with bivalves.

You also see Porcelain crab with their strange, squashed bodies.  Decorator crab, often festooned with bits of seaweed can be seen too.  Hermit crabs spend much of their time in this zone.

Lower tidal zone: Spiny Decorator crab, Sugar kelp, and blue ray limpets

Rocky shore Lower tidal zone: Biotic factors

Flip side? Biotic (rather than physical) factors. Far more predation.  And intense competition for space and things to eat.  Of course, with the physical factors being so much easier to handle, many organisms will migrate from this zone to the Mid tidal once the sea covers them.  There they can eat and predate on other species before retuning to the safety of the lower shore before the tide exposes them again.

Rocky shore Lower tidal zone

You even get sun-stars.

The biological factors such as predation and competition are extreme here.  Predation is fierce.  And competition for space in intense.  Yes, you don’t get smashed up by waves or dried out twelve hours a day.  But you do get eaten, and may well find it impossible to get a foothold in such a heavily populated zone.

Seahorse family groups

Some seahorse and pipefish species will spend time in this zone, although drying out is a real problem for them, so they tend to stay in the sub littoral.

Rocky shore: Sub littoral

Below the lower tidal zone is the sub littoral.  This area of the shore is never exposed to the air, not even at the lowest of tides.  It tends not to figure in rocky shore zonation as it’s more like shallow ocean than the shore.  Fish, crabs, lobster, kelp forests all abound here.

American lobster Homarus americanus

Complicating factors: Rockpools

Rockpools are vital for lots of these organisms, although they can suffer from enormous halinity and temperature fluctuations.  But to the aspiring rocky shore ecologist, rock pools can be confusing,  As they remain wet, you get organisms living there that should not be seen in the Upper tidal zone, or mid tidal areas of the beach.  Luckily, this is catered for by ecologists who examine rock pool life as a subset of the larger ecosystem.

The illustration above was done many years ago.  I now know that brittlestar (lower littoral specialists) and razor clams (sand living specialists) are unlikely to appear in any European rockpool.  You live and you learn.

Complicating factors: Exposure

It should also be remembered that the exposure of a rocky shoreline will have an enormous effect on the life there.  High exposure means it’s even harder to exist in the splash zone and Upper tidal.  More sheltered shores offer an easier existence.

Conclusion

This is truly a whistle-stop tour of the zonation of the rocky shoreline.  I have no doubt this blog is peppered with mistakes.  The FSC course tutor, John Archer Thompson probably has his head in his hands as he reads my version of his wonderful teaching.

As an excellent launch pad to much more on this subject, thanks to John, please check out his FSC rocky shore pages.

The post Rocky shore ecosystem illustration appeared first on Lizzie Harper.

As a scientific illustrator, you need to be able to feel confident using pen and ink.  Often pen and ink is the best medium for a diagram as it’s exact and clear.  Other times, commissioners like the traditional look of pen and ink illustrations.  This week and next week’s blogs are an overview of what you can achieve with pen and ink, and how to do so.

Line work

Before being able to work into tone in pen and ink, you need to be confident of your lines.  Try to use long and confident lines; a good way to practice this is to sketch with ink pen instead of pencil for a while.

You could also go over pencil lines with ink, trying to follow them accurately.

Drawing permanent ink lines accurately, and not being able to disguise errors with tone is really tough; but required for diagrams.  Computer programmes are a great help, although I still do my work by hand.

Different pressure, different strength of line

You can darken a line by pressing harder, and lighten a line with less pressure.  You can even break a line in its palest areas by using a few spots instead of a solid line; the eye will register it correctly and it adds depth.  This garlic plait appeared in Alan Titchmarsh’s How to Be a Gardener.

Sometimes these simple diagrams need to be quite complex; just remember that the illustration has to read clearly without any tone.  These fruit tree types were also in How to Be A Gardener.

If you’re asked to do an illustration involving straight lines, do use a ruler; trying to draw accurate straight lines freehand is not something I’d relish.

from Alan Titchmarsh’s “How to Garden” series.

Stippling

Stippling is basically building areas of tone with loads of tiny pen marks.  Different illustrators prefer to use different marks; I like using tiny dots, others favour short lines, or cross-hatching.  The effect is the same in all cases, building up dark areas with ink.

Crustacean family members, done for London Aquarium

Larger pen and ink compositions

Once you’ve mastered line work and stippling, pen and ink can be used to illustrate anything; from a detailed picture of animals to complex landscapes.

Members of the Seahorse family, done for London Aquarium.

Rice paddy and coral reef scenes done for WWT the Wetland Centre

Materials for pen and ink work

The materials needed to work in pen and ink are really simple.  First, you need a pen.  I use disposable permanent ink pens with small nibs (0.2, 0.1, and best of all 0.05).  Many companies make these (Staedtler pigment liner, Micron Pigma); they’re all good.  I work onto high quality cartridge paper such as Daler Rowney HeavyWeight, although many illustrators prefer to work onto board.

Pen and ink technique excersize

As a way to improve technique, try the following excersize.

A                                   B                                        C                              D

Draw a circle in pencil (A), then go over it in ink (B).  Try to follow the pencil with one steady ink line.  If you need to break the line (shown by the arrows on my diagram), leave a tiny space between it and the next, you can always fill this in with a tiny dot and that looks less clumsy than possible overlap would.  Next, using little dots, work in from the ink line to the centre of the circle (C).  The spots will be dense near the perimeter, but much farther apart towards the centre.  It takes ages, don’t be discouraged.  Decide where your light source is (shown by an arrow), and make sure you’re consistent with this.  It may help to shade your dark areas with pencil, then rub them out once the ink has dried.  Don’t make your areas of light too spotty, and try to keep the spots small.  Keep going until you’re satisfied (D).  Once you’ve mastered this technique you can draw anything using the same approach.

Pen and ink techniques with colour…next week’s blog

Next week’s blog shows you how to make these pen and ink images work in colour; it’s alarmingly easy.  In the meantime, good luck with your stippling; and remember to shake your arm out every 5 minutes or so, it really helps keep the cramp away!

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