What are cuttlefish?

Cuttlefish are related to squids and octopuses – a group of molluscs known as cephalopods. They have a well-developed head, large eyes and mouths with beak-like jaws. They have eight arms plus two feeding tentacles around the mouth and a fin that runs around their body. Cuttlefish are extremely variable in colour, but are usually blackish-brown, mottled or striped.

Common cuttlefish are the largest found in UK seas and are fierce predators . They make light work of crabs, fish and even small cuttlefish! They can live in water up to 200 metres deep but come to shallow waters to breed in spring. Their eggs are dyed black with cuttlefish ink, giving them the name ‘sea grapes’.

Cuttlefish can quickly change colour and texture to merge into the background and escape detection. This ability is also used to distract predators or attract mates. During spring and summer, males engage in spectacular displays to attract females, passing pulses of colour rapidly along their bodies.

About the summer project for Nature Bureau

The common cuttlefish is the most important commercial species in the northeast Atlantic, and the English Channel population accounts for most of the species abundance. Before the year 2000, this population reproduced from February to July at 2 years old. After reproduction, all cuttlefish quickly die, so the entire life cycle is 2 years. In recent decades, because of climate change and ocean warming, a large proportion of the Channel cuttlefish population (10-30%) have begun to reproduce and die at just I year old.

After death, the body decomposes or is eaten by scavengers and the cuttlebone, which is lighter than water, floats up to be washed ashore, sometimes far away from spawning sites. These cuttlebones do not remain on the shore for long periods of time, as seabirds eat them searching for calcium. Therefore, when found, a cuttlebone is likely to belong to a 1 or 2 year old Channel spawner.
We can use the cuttlebones to age the cephalopods and determine whether they are reproducing (and therefore dying) at a younger age due to global warming.

Aims

1. To estimate actual proportion of cuttlefish that halved their lifecycle due to climate change.
2. To get an idea of seasonal changes in the relative abundance of 1 year old spawners.
3. To provide in situ materials to verify the size – related natural mortality of cuttlefish for developing a 2-stage model.

Instructions

Cuttlebones
1. Common cuttlefish (Sepia officinalis)
2. Pink cuttlefish (Sepia orbygniana)
3. Elegant cuttlefish (Sepia elegans)

1. Find an intact cuttlebone on the shore.
2. Be certain that it is the cuttlebone of a common cuttlefish (the photo above will help you decide). Aside for the common cuttlefish (Sepia officinalis), cuttlebones from the pink cuttlefish (Sepia orbygniana) and the elegant cuttlefish (Sepia elegans) may be found, but they are much smaller, rare and should be ignored for this study.
3. Once you have located a common cuttlefish bone, pick it up and measure its length with a ruler, and record the measurement as well as where you found the cuttlebone (e.g. the name of the beach/town).
4. Then take a clear photo of the underside of the cuttlebone (the flat bottom as opposed to the rounded top), making sure it is in bright light and that the entire cuttlebone is visible in the photograph. The photograph will then be used by Athena to determine the age of the cuttlefish at death.
5. Break the cuttlebone in two so that it is not measured again by somebody else (Celas staff are also carrying out this work).
6. Email the measurements and their corresponding pictures to Athena ([email protected]), making it clear which measurement applies to which picture.

Fun facts about cuttlefish

• They can change colour in 200 milliseconds, as fast as a human can blink. 
• They have W-shaped pupils which are thought to help control the intensity of light entering the eye.
• They have three hearts, two of which pump blood to its gills, while the third circulates blood around the body
• They have blue blood, thanks to the copper-rich protein it contains known as haemocyanin, which transports oxygen around the body. Our blood is red due to its iron-rich haemaglobin, which does the same job.
• They have a doughnut-shaped brain, boasting the largest brain-to-body ratio of all invertebrates.
• They can squirt clouds of ink to create a smokescreen and escape predators.
• Cuttlefish might dream. Recently, researchers filming European cuttlefish in the lab observed short periods during their sleep-like states where individuals would erratically change colour and body pattern, and make irregular eye and arm movements. This strange behaviour, which was not repeated when awake or during inactive periods of sleep wasn’t triggered by any external stimuli and was very different from normal cuttlefish activity. 

From BBC Wildlife magazine

Seashells have many stories to tell us about the sea, what lives there and how everything is connected. Every day, as the tide ebbs and flows, new shells are washed up on the beach. Next time you pick up a shell, take a moment to think about who made it and the life it might have had. All shells were once part of a living, breathing sea creature. How are they formed? What animals use them? And what will happen to them as our oceans warm ?

What are seashells?

An empty seashell is a mollusc’s abandoned exoskeleton. Soft-bodied animals use them as their home and protection, their place to hide, and an attachment point for their muscles to help them move. There are many different shells to find, made by different kinds of molluscs, all around our coasts.

Rocky shores are home to many sea snails such as limpets, dog whelks and periwinkles. Sea snails move by crawling along on a muscular foot. Limpets, like other gastropods have a toothed ribbon-like tongue called a radula, which they use to scrape away algae – leaving a zigzag pattern as they do so (see image above). As the tide goes out, limpets return to the exact same spot each time: their home scar. Their volcano-shaped shells are difficult to grasp, and they use their foot like a suction cup and glue themselves in place with specialised slime. These hardy creatures can withstand stormy seas and baking sun, and may live 20 years.

Sandy shores are home to many bivalves such as cockles and razor clams, each with a pair of roughly fan-shaped shells that clamp tightly together to keep their soft bodies safe inside. Sandy seabeds, with no hard surfaces for seaweeds to attach to, offer few hiding places, so many of these creatures live safely below the surface, extending a siphon (rather like a snorkel) to breathe and to feed (hastily withdrawn when danger is sensed).

How are seashells made?

Unlike crabs, lobsters and other crustaceans, which routinely shed their shells and grow new, bigger ones, molluscs keep their shells all their lives and make them bigger each season as they grow. If you look closely at the innermost whorl of a sea snail you may be able to see the tiny shell it had when it first hatched from an egg.

As it grows, a mollusc uses its soft body tissue, called the mantle, to lay down another layer of shell. Shells are mainly made of calcium carbonate. You can watch a short video here.

Like tree rings, seashells have seasonal growth lines that are sometimes visible from the outside. Counting the most prominent lines across a bivalve shell can give you an idea of how old it was when it died.

Many marine molluscs live for several years, and some for much longer. Ocean quahogs from the North Atlantic can live for centuries. One individual, nicknamed Hafrún, meaning ‘mystery of the ocean’ in Icelandic, lived for 507 years, making it one of the longest-lived animals to have its age accurately measured.

Scientists use seashells, especially long-lived ones, as climate archives that hold detailed information about the changing ocean. Shells can tell the past temperature and acidity of seawater the molluscs grew in; they can even indicate when volcanoes erupted or hurricanes struck.

Why do seashells have different shapes?

Shells seem to come in an endless variety of shapes, but they are generally versions of a spiral. That’s obvious in sea snails and less so in clams and other bivalves but their shells are spirals too, just ones that flare wide open. The precise shape of their shells are due to their different habitats and ways of living and moving.

Molluscs may also increase their defences by adding corrugations and spines to their shells, making them difficult for predators to handle. Spiny oysters in the Mediterranean are covered in prongs that encourage seaweeds and sponges to settle and grow, giving them camouflage on rocky reefs.

How do seashells get their colours and patterns?

Lots of molluscs add a shiny layer of mother-of-pearl, or nacre, to the insides of their shells. This is designed not for beauty, but for strength, as its structure helps to make shells crack-proof. Other molluscs secrete pigments in their shells that help hide them in their habitat. Flat periwinkles have rounded shells that resemble the green and brown gas chambers of the bladderwrack seaweeds they inhabit along rocky shores. Janthina snails float below the sea surface, suspended from a raft of air bubbles and their shells are deep violet-blue, camouflaging them in open water.

Scientists have not yet worked out exactly why molluscs evolved their shell patterning. One idea is that they use their patterns as a marker to guide them as they lay down more shell material. Shell-making is not a continuous process, so a mollusc needs to remind itself where the previous growing season left off, so it can align its mantle and grow in the right places, or it could end up with a wonky shell!

Who else uses shells?

We are not the only shell-collecting animals. Hermit crabs have lost the ability to make their own shells and must instead borrow empty ones. When the time comes for them to find a bigger shell, they organise themselves into orderly queues, with the smallest individual at one end and the largest at the other. Two big crabs may tussle over the biggest, best shell. Once their contest is decided and the victor claims the prize, all the other smaller crabs move into the vacated shell of the crab next in line.

Down in the deep sea, carrier shells (Zenophoridae) pick up empty seashells, pebbles and coral fragments, gluing them onto the outside of their shells as extra defence from predators.

And the most intelligent molluscs of all, the octopus, has learned how to use seashells as tools. Like hermit crabs, octopuses’ ancestors gave up the ability to make shells long ago. But they have been observed using a pair of matching clam shells to make into a shelter if they feel threatened.

Based on an article by Helen Scales on BBC Discover Wildlife.

How will shellfish be affected by climate change?

Every year, the ocean is estimated to absorb more carbon dioxide  (CO₂) as than all the world’s forests do. That may seem like a good thing for humanity – the more the ocean can absorb, the less CO₂ remains in the atmosphere to drive the greenhouse effect that’s behind climate change.

But scientists are concerned about all the CO₂ the ocean absorbs. Absorbing CO₂ makes the ocean more acidic – this is known as “ocean acidification” – and this makes it difficult for crabs, clams, and other shellfish to grow their shells as strong as they need to be, and they can die as a result of ocean acidity.

Our sea shell challenge:
can anyone beat Andy’s record of four wentletraps?

What are wentletraps?

Wentletraps are marine snails with unique shells that form a high, conical spiral and have deep sculptured ribbing. They sometimes have a porcelain-like appearance. Most are white and no more than 5 cm long. Their name in Dutch means spiral staircase.

Wentletraps are widely distributed, from the tropics to the Arctic and Antarctica. They prefer sandy or muddy sediments and are often found near anemones or coral, from which they get their nourishment. The common wentletrap (Epitonium clathrus) is found in European waters.

The precious wentletrap (Epitonium scalare) was a rare and desirable specimen, which exchanged hands for large sums of money in the 18th century. As they became more common, they were still valued for their beauty.

Further reading

There are many books about shells and the seashore, but here are a few enjoyed by Strandliners.

Shells:
Spirals in Time, The Secret Life and Curious Afterlife of Shells by Helen Scales
Shell Life on the Seashore by Philip Street

Shell ID Guide:
Wild ID Common Seashells of Britain and Ireland, Field Studies Council

Beachcombing:
The Essential Guide to Beachcombing and the Strandline by Steve Trewhella and Julie Hatcher

Sea glass is naturally weathered glass, having the appearance of tumbled stones, with smooth edges and a frosted appearance. It is also known as drift glass, from the process of longshore drift that wears it. It may take 20-40 years, sometimes as much as 100-200 years, to take on its characteristic appearance.

Where does it come from?

Sea glass starts off just like any other shard of glass; broken, jagged and sharp. The travels of any one piece of sea glass have been long and tumultuous since it entered the sea, tumbled by the ocean and scoured by sands and stones. How any one piece got to the beach is a mystery, but there are some common routes by which many pieces wash up on your beach. The most common are as flotsam from shipwrecks and jetsam from sailing vessels. In some countries, where there is no waste infrastructure, general rubbish may discarded into rivers or the sea. You might even find a piece of a message in a bottle that didn’t make it in one piece.

Many years ago glass factories dumped their glass waste into the sea. An example of this is Seaham, a harbour town on the Durham Heritage Coast. Seaham is world-famous for its abundance of unique sea glass, making it a ‘must-see’ site for collectors. Seaham and nearby Sunderland were home to many bottleworks and glass-making factories during the Victorian and Edwardian eras, and Seaham boasted the largest glass bottle works in Britain – The Londonderry Bottleworks, operating from the 1850s to 1921. 

The bottleworks produced up to 20,000 hand-blown bottles every day, in different colours and designs including hand crafted bottles, perfume bottles and household glass, all of which were distributed across the globe. 

What about colour?

Sea glass has comes in many colours, depending on the type of glass it was made from. Different shades are determined by the chemicals used in making the glass, the temperate of the melt and the length of time it was melted for. Each colour tells us a little about a nugget’s past. Colour rarity varies from country to country, but globally white is the most common and orange the rarest. The most common colours in the UK include white and green.

White sea glass, from colourless bottles, could have been an old milk bottle, a vase or jug, or even an old car windscreen.

Sea glass comes in many shades of green. Very dark green, almost black in colour, may have come from bottles holding alcohol. The original Coca-Cola bottles came in pale green. Some olive oil brands still use iolive-coloured glass, just as it they many years ago. Bright emerald green was sometimes used for medicine or mineral bottles , and various shades of green were used for fishing buoys. if you find a mermaid’s nipple it has come from a fishing buoy (no mermaids were harmed in the making of these).

An increasingly rare green sea glass is uranium glass. This had uranium (usually in the form of one of its oxides) added to the mix before melting. The amount of uranium varied from a trace to around 2% (some early pieces may have had higher levels). Uranium was added to decorative tableware and ornaments for its fluorescent effect under UV light. The production of uranium glass dropped dramatically from the 1940s, when supplies of uranium were diverted towards the manufacture of nuclear weapons or nuclear power. The yellowish green uranium glass was sometimes called Vaseline glass, due to its perceived resemblance to the colour of petroleum jelly.

Cobalt glass includes a cobalt oxide or carbonate compound in the mix to produce the typical rich blue colour. Cobalt glass was traditionally used for apothecary poison bottles. Other uses include glasses for professional olive oil tasters to hide the colour of the oil, and for flame testing in chemistry labs. Bristol blue glass is popular with collectors – used for Harvey’s Bristol Cream sherry and Tŷ Nant mineral water.

Black sea glass, hard to distinguish from the shingle, isn’t actually black; if you hold it up to the light, you will see shades of either brown or green. Hundreds of years ago, very dark, thick glass was needed to keep the sunlight from spoiling alcohol such as rum, gin and beer.

Rarer colours like red, orange and yellow are highly sought after by collectors (see rarity chart below). Red may have been used for maritime lights or fancy tableware. Bright orange sea glass is very rare. It may have come from old lanterns, carnival glass or the taillights of old motor vehicles. Sea glass can also be found in pink and lavender. These are also rare colours now, but once were cheap and cheerful tableware.

What about size?

Just like pebbles, sea glass pieces carried along the coastline and are subjected to sorting. This is where the ocean’s currents and tides sort the pebbles by size and shape, depositing them on the beach in a specific order. The process of winnowing is the natural removal of fine material from coarser material (larger pieces) by wind or flowing water. Once a sediment – including pieces of sea glass – has been deposited, subsequent changes in the speed or direction of wind or water flowing over it can agitate the grains and allow removal of the finer pieces.

I am obviously looking in the wrong place, as I only ever find the tiniest pieces of sea glass. Well done to our keen observers who have been sharing their sea glass finds on Rye Bay Beachcombing recently.

Big Seaweed Search

This is a great half-term activity for the children, or indeed for anyone at any time. The Big Seaweed Search is a partnership between The Natural History Museum and the Marine Conservation Society.

Why are seaweeds important?

The UK is globally important for seaweeds, being home to more than 650 species. Seaweeds create underwater habitats that provide food and shelter for thousands of marine organisms. They support commercial fisheries (providing nursery grounds for juvenile fish; they absorb carbon dioxide from the atmosphere; they are used in foods, cosmetics and medicines; and they protect our coastlines from storm damage.

What am I looking for?

By exploring the seashore and recording the living seaweeds you find, you are helping to monitor the effects of environmental change on Britain’s sea life. You are taking part in a real citizen science programme which focuses on three key environmental changes: sea temperature rise, ocean acidification and the spread of non-native species.

What do I have to do?

The instructions can be found on the Big Seaweed Search website, but are basically as follows:

1. Start around an hour before low tide.
2. Select a 5-metre width from the top of the shore to the sea.
3. Walking away from the sea, explore the whole plot for about an hour, recording only living seaweeds attached to rocks or another hard surface. You only need to record the species from the guide. It is important that photographs are taken as evidence. Photographs are essential for the BSS to be able to use your results.
4. Upload your results and photographs, using the online form or the app.

Remember to stay safe on the beach. Tell someone where you are, take a mobile phone, wear sensible clothing and footwear (rocks are slippery and may be encrusted with barnacles), don’t go out in bad weather, and wash your hands afterwards.

You can find the Big Seaweed Search guide here
and the Big Seaweed Search recording sheet here.

Meet seaweed researcher Juliet Brodie and Big Seaweed Search participant Jazz in this short video and learn more about why seaweeds are important and how to take part (3:46 mins).

Sussex Kelp Recording Project

What is kelp?

Kelp are large brown seaweeds found along rocky shores. Like marine trees, kelp create a ‘canopy’ beneath which many species takes shelter and find food.

Why is kelp important?

The organisms that shelter and feed here include commercial fish and crustaceans, so kelp supports local livelihoods as well as providing other benefits for nature, people and the planet. Kelp locks away carbon, filters the water and protects our coast from storms by dissipating wave energy.

Vast kelp beds along the Sussex coast (mostly towards the west of the county) once supported a wondrous diversity of marine life. But by the late 1980s, 96% of Sussex kelp had disappeared. This project aims to bring it back.

The journey to kelp recovery started with the Sussex Nearshore Trawling Byelaw. This pioneering legislation created one of the largest trawling prohibited areas in the UK in March 2021. At the same time, the Sussex Kelp Recovery Project was formed to champion, study and facilitate the return of kelp through through progressive, coherent and collaborative action. Find out more here.

There are more videos on the website, but this one, narrated by David Attenborough, launched the project.

You can be part of SKRP’s research programme

Citizen science is a growing discipline that enables us to participate and collaborate in real scientific research and increase scientific knowledge.  We can get involved to help deliver SKRP aims.

Everyone can contribute to restoration efforts via a handy app from the Sussex Wildlife Trust. Whether you’re an occasional beach walker or an avid scuba diver, you can record any kelp you’ve seen on the beach or out to sea, and play your part in the Sussex Kelp Recovery Project. You can register here and find out more about this citizen science project.

A hagstone is a stone with a naturally formed hole. Traditionally, hagstones are flint, the most abundant pebbles on our beaches in South-East England, typically grey or brown in colour and worn smooth and rounded by the action of the sea.

What is flint?

Flint is a microcrystalline sedimentary rock composed of silica, formed from the remains of sea sponges and planktonic organisms such as diatoms and radiolarians during the late cretaceous period (60-95 million years ago). Flint was formed in sediments that later became chalk, and so it is found in areas with chalk bedrock, such as the South Downs. As the chalk cliffs erode, the flint is exposed and deposited on the beach.

How do holes form?

To be considered a hagstone, the hole should have been made naturally. Holes are often made by the wearing away of softer inclusions, for example a fossil sponge embedded in the silica. Sometimes minerals are deposited in small pockets within a rock as it forms. Later these small deposits may weather and erode more quickly than the surrounding rock. The hole may be very small to be begin with, even just a dent, but can be made larger by the action of smaller stones grinding against them through wave action

Softer rocks such as limestone or sandstone may have holes made by the activities of marine animals such as burrowing bivalves, marine worms or sponges. These might not have been thought of as hagstones.

Hagstones in folklore

Stones with natural holes play a large role in European folklore. They are are also known as witch stones, adder stones, druid stones, fairy stones or dobbie stones. They were believed to have magical properties, protecting the bearer from witches and ne’er-do-wells.

One belief was that only good luck can pass through the hole, whereas bad luck and curses became ‘stuck’. It was also commonly thought that magic could not work on objects that water can pass through. As the stone’s shape resembles an eye, it acted as a talisman to ward off ‘the evil eye’ (a prominent tradition in Eastern Mediterranean and Western Asian culture). The hole in a hagstone was even thought be a portal to the faerie world and could bring good luck to anyone able to make contact.

Traditionally, hagstones were placed on windowsills or above doors to bring good luck or to ward off evil. They were hung with a red ribbon above the bed or nailed to the bedpost to protect against nightmares. Across Britain, they were hung above stables, sometimes tied to a piece of iron (which also repels witches) to stop witches riding the horses during the night or above cattle sheds, to stop witches turning the milk sour.

In Dorset, fishermen used a hagstone as a protective amulet, threaded onto the rope used to haul the boat up the beach: the boat was thought to be witched if it did not bring in a good haul. In sailing ships, hagstones tied to the mast or a line of stones tied together with string and nailed to the hull were used as protective talismans to ward off witches or to attract good sailing conditions at sea. This tradition was particularly prominent in the South-West. In Sussex there are records of stones with holes used by a midwife to cure children’s diseases and prevent adults catching them. Other uses included tying one to your keys to stop them getting lost, and worn as a pendant for personal protection.

Hagstones were often thought to have been formed by adders: traditionally, on the evening before May 1st, there was a gathering of snakes, which curled together in a ball with a hole in the middle, leaving their hardened saliva behind. In The Mabinogion (the earliest Welsh prose stories) such a stone helps Peredur to escape a lake monster and Owain to escape a castle by becoming invisible. Another theory is that the hole is caused by the bite of an adder: giving rise to the notion that the stones could protect against snake bites.

Local stories

Hastings is supposedly under an enchantment known as Crowley’s Curse, put on the town by author and ceremonial magician, Aleister Crowley. It is said that anyone who has lived in Hastings is compelled to return, no matter how far away they move or for how long. The curse can only be broken by taking a hagstone from Hastings beach!

There is an interesting article in the journal Elementum, entitled In the Eye of the Hagstone, Under the Spell of Flint on the Sussex Coast, by Alex Woodcock. You can read it here.

Whatever you believe, perhaps there is still magic in a mindful walk along the beach, whether we are removing plastic pollution from the environment, looking out for special treasures, or just enjoying the sea air.     

We must add a disclaimer here: under the Coastal Protection Act 1949, the removal of any natural material, such as sand and pebbles from beaches in the UK is illegal.

Some sharks, and all true skates, reproduce by laying eggs. These are surrounded by a tough leathery capsule (made of keratin) that protects the embryo as it develops. After several months these are ready to hatch, and a fully-formed shark or skate will emerge. 

Once empty, the egg cases (or mermaid’s purses) often wash up on the beach. The best places to find them is among the strandline, where the seaweed washes up. By looking at the size, shape and features of the egg cases you find, you can tell identify the species.

The Great Eggcase Hunt began in Devon twenty years ago. It now asks us to become citizen scientists by looking for egg cases and recording our finds. These can indicate species presence and diversity.

Preparing your egg cases

The egg cases washed up on the strandline are often dried out. Rehydrating them makes them much easier to identify, as they expand to their true size.

Fill a container with freshwater and submerge the egg cases. leave to soak for several hours, especially if they are large or very dry. Remove from the water and compare to the ID chart. Don’t forget to take measurements – and photographs – then you can upload the results to the Great Eggcase Hunt website.

Identification

You can find the ID guide here.

You can find the ID key here.

You can also download the Shark Trust App and use this to identify and record the egg cases you find, straight from your phone. If you prefer, you can upload your results through the recording hub. You can see the findings on an interactive map.

The 2023 Great Eggcase results can be found here.

There are lots of ways you can help the Shark Trust by becoming a citizen scientist. You can find out more here.

Spotlight on Undulate Rays

Easily identified by its beautiful pattern, as seen in the video, the Undulate Ray gets its name from the wavy patterns of lines and spots on its dorsal side. Despite being called a ray, it is actually a skate. One difference is the tail – a skate’s tail tends to be stockier, whereas a ray’s is more slender and whip-like (some rays have a stinging spine on the tail). Another difference is that skates generally lay eggs in capsules, whereas rays retain the eggs inside their bodies and give birth to live young.

The Undulate Ray normally lives on soft sandy or muddy sea beds, where their markings help to camouflage them against the sea floor – they often bury themselves just below the surface. They can live for over 20 years and grow up to 90 cm total long. Depending on the size of the individual, their diet can range from small fish to shrimps and crabs.

The Undulate Ray is an endangered species globally according to the IUCN Red List and is a priority protected species in the UK. The threats they face include overfishing and habitat loss. We are lucky here in Sussex to have a thriving population of Undulate Rays, perhaps due to the Marine Conservation Zones we have here, which are allowing the natural restoration of our inshore waters.