Follow the Coast Path from above Seahouses harbour, southwards towards Beadnell.   You'll skirt round a mobile home park and then make your way along the edge of some major cliffs - home to nesting Kittiwakes in due season.   Then the path takes you across a part of Seahouses Golf Course and back down towards a rocky/pebbly section of beach: that is Snook Point on the Ordnance Survey map, at grid reference NU228315

Seashores provide perhaps the most compactly varied ecosystems anywhere in the world.   Over a range of a hundred or so metres in distance and less than a dozen vertical metres a range of self-contained communities blend systematically into each other and their surroundings.   Let's not be coy about it, the facility at Snook (or North Sunderland) Point is a concrete path that did not become redundant until some £13m+ had been spent on the new award-winning sewage treatment works on the outskirts of the village.

On a serious note, SAFETY must be your over-riding first concern.   The current score is one air-ambulance evacuation from this area of a casualty with orthopaedic injuries in each of the last two years.

Dry rock which sparkles (sandstone) is usually safe.   So too are any rocks liberally colonised by barnacles -

That's a six-inch ruler, by that way - 15 centimetres.  It features in a number of these photos to give an idea of scale.

But rounder shells are remarkably strong too and can act like ball-bearings -

- while anything even remotely weedy is bound to be slippery -

- and beds of seaweed are more treacherous than ice - just as slippery but hiding all the bumps and hollows.

PLEASE  TAKE  CARE
ALL EXPLORATIONS ARE DONE ENTIRELY AT YOUR OWN RISK.

Different ecosystems are to be found at different levels on this (or any other) rocky shore.   Ecologists would classify this as an "exposed rocky" section of coast.   The "exposed" adjective really applies here only during gales coming in from the east, which are relatively rare when compared with the Atlantic battering suffered by comparable shores on the west coast.   But it certainly doesn't benefit from being "sheltered" like some estuaries or sea lochs for example.

The location and range of each identifiable ecosystem here depends not on distance from the shore, not even on depth of water, but on the TIME that each square metre is DRY during each twice-a-day tidal cycle.   This being the case it quickly becomes clear that plant and animal communities are different above and below mean (average) sea level - "MSL".   Now the range of tides varies with the stage of the month - or fortnight actually.   The biggest tides occur when sun and moon are more or less aligned, together or directly opposite one another: so these spring tides happen once a fortnight near full and new moons.   Incidentally, by "biggest" we mean the highest high waters together with the lowest low waters.   In between times, when sun and moon are at right angles to one another the tides of smallest range are the neap tides.   But none of these factors are simple and obvious: it takes a Hydrographer to work out the maths for exact predictions.

The ecology of the top end of the shore is affected both by MHWS, (mean high water springs), and EHWS, (extreme high water springs).   Similarly, those species most likely to suffer severely from even the briefest period of drying are influenced by MLWS, (mean low water springs) and perhaps even by ELWS, (extreme low water springs).

The tidal range at Snook, assumed to be identical to that within Seahouses harbour, is from a high of 5·44 metres above ordnance datum at Newlyn, Cornwall, to 0·27 metres at ELWS, a maximum vertical range of some five and a quarter metres, seventeen feet.



The presence of scurvy grass and thrift amongst the grass immediately above the beach might be attributed to its salty circumstance.

But the highest true indicator of the marine environment is the presence of a slightly sooty-looking layer on the otherwise bare rocks (most clearly over to your left as you face out to sea).



(a) is the splash zone layer, darkened by the extremely tough microscopic lichen Verrucaria maura.
(b) is simply the shadow within the small cave there.

The most obvious inhabitants of the otherwise bare rocks are the limpets and barnacles.   There are several types of limpet to be found around UK shores but the only species present here is the rightly-named common limpet, Patella vulgata.   Although each animal appears to be a permanent fixture it feeds by moving around, 'grazing' its immediate area while it is under water, returning exactly to its home station where its shell forms an almost airtight fit with the rock.   Some congregate in sheltered hollows while others brave total exposure to sun and surf.   Any that finally succumb leave behind temporary scars of their occupation.

Next most obvious are the millions of barnacles which truly are permanently static once each has found a home for itself.   Apparently dead (as indeed some of them are!) they can feed only when covered by the tide, catching microscopic plankton and detritus with nets waved above their openable central plates.

These are acorn barnacles, Balanus balanoides






Apart from the encrusting lichens and some microscopic vegetation which nourishes the limpets, the highest obvious plant life consists of the first of the family of "wrack" algae.   None of the algae produce flowers: instead they reproduce from enlarged 'conceptacles' towards their tips.   Algae come in red, green and brown families: all the wracks, and kelps which we meet lower down, are manifestly browns.

This channelled wrack, Pelvetia canaliculata, is the smallest of the wracks, extending right up to mean high water level.   Although evidently very tough it forms only a relatively narrow band: other species can out-compete it wherever conditions are slightly easier - slightly less exposed to prolonged drying.

There are much smaller numbers of green algae.   There is usually only one to be seen at this level - gutweed, Enteromorpha intestinalis, named from its resemblance when floating to small green intestines!

Small periwinkles, Littorina neritoides, are to be found anywhere on the upper shore - on drying rocks, in shallow pools, often gathered in large numbers in crevices and hollows as here - seen as the tide is coming in to re-wet them from the left.   They graze on lichens and other vegetable matter in the area.


Not all marine lichens share the dull colour of the splash zone.   While not covering any large areas, a white lichen, Lecanora atra is to be seen on many stones and boulders where they are dry for part of the day.






It is on the mid-shore that the wracks achieve almost total dominance.   These brown algal seaweeds, slimy to the touch and slippery to the feet, can be highly productive and luxuriant despite being exposed to drying-out for anything from a quarter to three-quarters of their day.   There are a number of these wracks, Fucus species, - not always easy to identify despite their differing appearances.   Hybrids can sometimes occur with some characteristics of both parents.   The normally common bladder wrack, Fucus vesiculosus, seems to be remarkable here by its absence.

Be that as it may, wracks do not have this mid-shore environment entirely to themselves. The red tinge in this pool is due mainly to a very ubiquitous red alga called coralweed, Corallina officinalis.   It is one of a small group of algae that accumulate lime within their tissues.


Many pools house mixed gardens of algae.

(a) is coralweed again.
(b) is a mass of filamentous red alga, probably Gracilaria verrucosa, blushing for want of a common name.
(c) is a wrack awaiting full identification.
(d) is the toothed wrack, Fucus serratus.

The lower shore remains largely under water throughout periods of neap tides.   The depth of water is greater and the periods of exposure considerably reduced compared with those on the higher levels.   It is here that larger species of brown algae can develop - the kelps.   Commonest by far is the oarweed or tangle, Laminaria digitata.   From a holdfast on the rock a long stipe or stalk grows to bear a divided flat lamina.   The stipes are bendy, but sufficiently rigid to stick up above the water during low water springs.

Indeed, that ecosystem is sometimes referred to as a 'laminaria forest', though other species are present too, even including epiphytes growing on the stipes of the laminaria.

On the left, the red epiphyte is one of a whole group of possible red algae using the laminaria stipes for support.   The white sea mat on the right, seen after being stranded ashore, is in fact a cylindrical colony of zooid animals.

Almost identical in colour to the oarweed (b), sugar kelp (a) (Laminaria saccharina) has a ruffled lamina with a mid-rib.   In contrast, complementing the big brown algae and colonising spaces between their holdfasts, lesser algae and encrusting lichens occur, as shown below between the cuvie plants, Laminaria hypoborea.

In contrast, complementing the big brown algae and colonising spaces between their holdfasts, lesser algae and encrusting lichens occur, as shown below between the cuvie plants, Laminaria hypoborea.


Looking up-shore from the low-water end of the path -

Higher than the Laminaria kelps (a) are the Fucus wracks (b).   [Those exposed rocks over there are nearly all carboniferous limestones from 300m years ago.






Largely hidden down below are such things as the pink Corallina we met earlier, with a filamentous green companion alga.










Another of the few green algae is the very thin, apparently flimsy sea lettuce, Ulva lactuca. There is not a lot of it in the Snook area but a few patches do occur on the left, fairly well down the path.   It looks extremely vulnerable but is actually a very tough plant.


Another apparently insignificant almost spongy dull red plant is Lithophyllum incrustans.   It produces a very tough layer, often a centimetre or more in thickness.





Lesser than the kelps but much more significant than these lowly species, thongweed, Himanthalia elongata, can be dominant in some patches.   Its branches can grow to exceed two metres in length, originating and regenerating from characteristic button-shaped initials.

(a) is the thongweed on a rock and waving in the water.
(b) is some fully immersed Laminaria











A few common limpets are found within these low-water systems.   But they may be a different sub-species, smoother-shelled and less pointed than their cousins higher up the shore.






The myriad animal inhabitants may not show themselves to the casual explorer.   They need to be so adept at predator-avoidance that they hide permanently or are well camouflaged, and the majority of movers do so with blinding rapidity or at an almost undetectable snail's-pace.  

So the chances are that if you do discover a denizen of the deep it is probably a casualty of some sort - perhaps a dead worm pipefish, Nerophis lumbriciformis, with its characteristic shape and hard-plate exterior that renders it rigid in death.


In life it would have been scurrying through the laminaria forest, whereas a healthy octopus would normally be out beyond tidal depths.   The wisp of its black ink shows clearly against the white ruler.The small starfish might well have been at home, patrolling between the stipes of the kelps.

About the only denizen likely to return your stare of interest would probably be on holiday on the mainland from its normal stomping ground on the Farne Islands, within sight from parts of Snook Point.



The grey seal looks astounded at being named Halichoerus grypus, but is best left to contemplate his problems without disturbance: it is very unlikely to be a case of unintentional stranding - even if the youngster seems singularly to fail to qualify as a 'grey' seal at all!