Collins Complete Guides – British Coastal Wildlife

INTRODUCING THE STRANDLINE

A beach marks the zone where land meets sea. It is also where detached and floating matter is washed up and deposited by the tides, typically in well-defined lines. During periods of spring tides, debris is pushed to the top of the shore. But with approaching neap tides, tidal extremes diminish and the high-tide mark drops; the result is a series of different strandlines on the shore. The strandline is a great place for the marine naturalist to explore and find unexpected delights washed up from the depths. But it is also home to a range of specialised animals that exploit the rich supply of organic matter created by decomposing seaweeds and marine creatures.

Cuttlebones are often found on the strandline.

FISH EGG CASES

Some species of sharks, skates and rays reproduce by laying tough egg cases, or mermaid’s purses, each containing a single embryo. Tendrils, or sometimes ‘horns’, at the capsule corners attach them to the seabed, where they may take many months to hatch; once the juvenile has emerged, the empty egg case will often wash up on the shore. The egg case of each species is different enough in terms of size and shape to allow certain identification of strandline finds. Soak the capsules in water for 24 hours in order to restore them to full size before measuring.

all capsules are lifesize unless stated

SPOTTED RAY Raja montagui – capsule long and slender; has 4 horns of similar length, 1 pair curled in at tip, the other curled upwards. (For adult)

UNDULATE RAY Raja undulata – long, smooth-surfaced capsule; has 1 long pair of horns with curled tips and 1 shorter pair that curl up like bobsleigh runners. (For adult)

BLONDE RAY Raja brachyura – capsule longer than broad, with 1 flat and 1 convex side. Has 1 pair of horns almost as long as capsule, and 1 pair much shorter and curved; these are often damaged. (For adult)

capsule shown at ½ lifesize

COMMON SKATE Dipturus batis – one of the largest egg cases. Capsule square; has fibrous, ragged appearance and short horns. (For adult)

SMALL-EYED RAY Raja microocellata – narrow, stongly curved capsule; has 1 very convex surface. Capsule narrows towards base of shortest pair of horns. (For adult)

THORNBACK RAY Raja clavata – capsule square and plump; has horns of equal length, up to half capsule length. (For adult)

NURSEHOUND or BULL HUSS Scyliorhinus stellaris – long, slender capsule; has a tough skin and long, curled tendrils at corners. May get washed up in bunches.

SMALL-SPOTTED CATSHARK or DOGFISH Scyliorhinus canicula – capsule small, relatively narrow and translucent; has long, curling tendrils at corners, and may be found in small groups. (For adult)

INTRODUCING SEASHORE FOSSILS

In parts of Britain, the seashore is a rewarding place to search for fossils. Constant erosion and deposition, cliff falls and storm damage ensure a regular supply of fossils to some beaches. These may range from magnificent ammonites, present in the seas 100 million years ago, to sharks’ teeth, or the footprints left behind by long-extinct species. As well as many animal remains, some plant material may also be fossilised, such as hard seed cases, woody tree trunks, or even delicate fern fronds trapped in layers of silt. Some fossils are embedded in rock and cannot be removed, but others may lie exposed in sand or mud at low tide. Sieving the sand or shingle can sometimes reveal small fossils such as sharks’ teeth, fish vertebrae or fragments of mollusc shells.

Fossil ammonite on Dorset’s Jurassic Coast.

AMBER – a form of fossilised tree resin, with a rich, translucent golden-orange appearance and smooth texture. Sometimes insects are trapped inside globules of amber and remain perfectly preserved. The S North Sea coast of Britain may yield fragments of amber.

FOSSILISED SHARKS’ TEETH – these are usually the only parts of the shark’s body to remain, being the hardest part (the skeleton is cartilaginous). Teeth from many species can be found; they are all usually black and very shiny, and often very sharp.

RAY DENTAL PLATES – these fish have crushing teeth arranged in plates, rather than sharp, pointed teeth; fragments are common in areas where other shark species occur.

NUMMULITES – disc-like fossils, the size of small coins, which are the remains of small planktonic organisms that had delicate calcified shells.

FOSSILISED HEART-URCHINS – these are sometimes found inland, in areas of chalk and flint, where they are referred to as ‘shepherd’s crowns’. They are the remains of urchins of the genus Micraster, and are also found on shingle beaches. (for living species.)

FOSSILISED COCKLES – members of the fossil genus Venericardia resemble present-day cockles; they are common in beds of clay on parts of the S coast of England.

FOSSILISED OYSTERS – recognisable as an oyster shell (for living species), fossil oysters mostly belong to genus Cubitostrea; they are found in dense deposits with other bivalves.

FOSSILISED TOWER SHELLS – fossils from genus Turritella are very similar to present-day tower, or Auger, shells.

FOSSILISED MUSSELS – bearing a strong resemblance to present-day mussels, fossils of mussel shells are often found partly embedded in limestone or shale on the shore.

HORNWRACK Flustra foliacea (length to 20cm) – bryozoan, commonly washed up on strandline, sometimes in huge quantities after storms. Looking rather like coarse seaweed, it is actually a colonial animal that lives just offshore attached to shells and stones. Live specimens have a faint scent of lemon.

SECURIFLUSTRA SECURIFRONS (length to 10cm) – slender bryozoan, less common than Hornwrack but still occasionally found in large quantities. Fronds are strap-like with short branches; there is a small basal holdfast.

WHITE WEED Sertularia cupressina (length to 50cm) – colonial hydroid that grows attached to stones and shells in shallow water; often found washed ashore. Colonies consist of a main stem, attached at base by a small holdfast, with numerous short feathery side-branches.

BOTTLEBRUSH HYDROID Thuiaria thuja (length to 25cm) – cylindrical, brush-shaped hydroid with numerous short stems arising from a stiff central stem. A N species that grows on shells and stones in shallow water; often washed up after storms.

SEA BEARD Nemertesia antennina (length to 25cm) – colonial hydroid made up of clumps of up to 50 stiff, branchless stems; these are attached at bottom by a tangled mass of tough, fibrous rootlets. Colonies grow in shallow water attached to shells and stones, and are common on most coasts.

ABIETINARIA ABIETINA (length to 25cm) – branching hydroid with thick, wavy central stems arising from a root-like holdfast that is often fixed to shells. Short side-branches grow alternately. Common on all coasts and regularly washed ashore.

MERMAID’S GLOVE Haliclona oculata (length to 30cm) – much-branched, antler-like sponge that grows on seabed well below the low-tide level. Tough remains, with a brittle texture when dry, may be found on the shore after storms.

SEA BEAN Entada gigas (length to 3.5cm) – drift seeds of many species originate a great distance from our shores; this species will have drifted across the Atlantic from the Caribbean or Central America. The seeds form in a pod on a climbing plant in the pea family, and drop into the sea; their buoyancy and resistance to salt water enables them to survive long periods afloat. Occasional, in the W.

HORSE-EYE SEA BEANS Ormosia sp. (length to 3.5cm) – originate in Central America and the Caribbean; the seeds of climbing plants in the pea family that is common on the shore and in low-lying areas. Occasionally found on beaches in SW England, S Wales and Ireland.

KELP HOLDFASTS – fronds, stipes and rootlets of most of large kelps rot away fairly quickly once washed ashore, but the tough base and lowest stipe section are tougher and last much longer, especially when dry. The most striking holdfasts are those of Furbelows; found on most coasts.

SEA CHERVIL Alcyonidium diaphanum (length to 25cm) – fleshy, non-calcified bryozoan that grows below low-tide level attached to shells and stones. Colonies are very variable in shape and size, but all have the same knobbly appearance and slightly rubbery texture. Handling it may cause skin irritation in some people. Found on most coasts.

SEA WASH BALL (length to 15cm) – spongy mass of smaller capsules, buff-yellow in colour: egg mass of Common Whelk or Red Whelk. Usually only one whelk emerges from the mass, after having eaten most of the other eggs. Found on most coasts.

Skulls and bones

The remains of fish, birds and mammals may all be found among strandline debris, and most can be identified with some degree of certainty. Birds can generally be recognised by the shape and structure of the bill. Fish bones are rather delicate by comparison, but sometimes a whole fish skeleton may remain intact. Often, however, it is only the individual vertebrae that are found. Mammal remains are more obvious, and large vertebrae of whales and dolphins are an occasional find on exposed beaches. In areas near seal colonies, seal skulls and vertebrae may also be found. Dolphin skulls have a curious beak-like rostrum, with sockets for the peg-like teeth, but seal skulls have a more recognisable mammal outline, with powerful incisor, canine and molar teeth.

bird skulls are shown ½ lifesize