Cephalothrix simula - An invasive non-native toxic species of ribbon worm TTX tetrodotoxin

For the press and everyone else, images on this page are not to be used without the written permission of the copyright holder David Fenwick. E-mail

Two specimens were found forming a knot under a Mytilus, Mussel valve that was stuck to the bottom of a rock. The rock being in a pool exposed by the extra low spring tide at Godrevy Point, nr. Hayle, Cornwall. 18.05.18. Species confirmed by molecular analysis. This was the first instance of the species being found in the UK. A paper has been produced by the author here and CEFAS Weymouth to support this find.

See paper-
New Invasive Nemertean Species (Cephalothrix simula) in England with High Levels of Tetrodotoxin and a Microbiome Linked to Toxin Metabolism.

Pacific Death Worm
Cephalothrix simula
- juvenile under microscope / ventral anterior / proboscis 1

Pacific Death Worm
Cephalothrix simula
- juvenile under microscope / ventral anterior closed mouth 1

Pacific Death Worm
Cephalothrix simula
- juvenile under microscope / ventral anterior open mouth 1

Pacific Death Worm
Cephalothrix simula
- juvenile under microscope / open mouth 1

Pacific Death Worm
Cephalothrix simula
- group of small juveniles 1

Pacific Death Worm
Cephalothrix simula
- group of small juveniles 2

Pacific Death Worm
Cephalothrix simula
- group of small juveniles 3

Pacific Death Worm
Cephalothrix simula
- anterior of juvenile 1

Pacific Death Worm
Cephalothrix simula
- anterior of juvenile 2

Pacific Death Worm
Cephalothrix simula
- anterior of juvenile 3

Pacific Death Worm
Cephalothrix simula
- anterior of juvenile 4

Pacific Death Worm
Cephalothrix simula
- anterior of juvenile 5

Pacific Death Worm
Cephalothrix simula
- group of small juveniles with 1.0mm division rule 1

Pacific Death Worm
Cephalothrix simula
- sample collection site 1

Pacific Death Worm
Cephalothrix simula
- sample in container 1

Pacific Death Worm
Cephalothrix simula
- sample 1

Pacific Death Worm
Cephalothrix simula
- sample 2

Pacific Death Worm
Cephalothrix simula
- habitat within 20m -1

Pacific Death Worm
Cephalothrix simula
- habitat within 20m -2

Pacific Death Worm
Cephalothrix simula
- habitat within 20m -3

Fifteen small juvenile specimens were found in a 150g sample of algae and bryozoan turf collected from a vertical surface on the extreme lowershore at Godrevy Point, near Hayle, Cornwall, 27.09.18. No juveniles were sequenced as the specimens were found within yards of the original find so we can be certain of their identity.

Pacific Death Worm
Cephalothrix simula
- micro habitat often found on the underside of Thongweed Himanthalia elongata buttons 1

Pacific Death Worm
Cephalothrix simula
- size of sample 1

A further two small juvenile specimens of Cephalothrix simula were found among the epiphytic flora and fauna that occurs on the holdfasts / buttons of Thongweed, Himanthalia elongata, 27.09.18.

Pacific Death Worm
Cephalothrix simula
- comparison between Poole and Godrevy specimens 1

Pacific Death Worm
Cephalothrix simula
- comparison between Poole and Godrevy specimens 2

Pacific Death Worm
Cephalothrix simula
- comparison in length between a small juvenile and a nearly mature specimen 1

Orange tentacles of the polychaete Polycirrus might be confused with juvenile specimens of Cephalothrix simula as they remain alive well after being detached from the worm.

Orange tentacle of Polycirrus (1)
Orange tentacle of Polycirrus (2)

IMPORTANT PLEASE NOTE:
The identification of this species is by DNA sequencing only.
The reason for this is that there are two other morphologically identical species that exist in the Asian Pacific, but so far none of them have been identified in Europe. The species can also be confused with UK natives. A good knowledge of nemerteans is needed to even tentatively identify this species.
E-mail for advice

See paper-
New Invasive Nemertean Species (Cephalothrix simula) in England with High Levels of Tetrodotoxin and a Microbiome Linked to Toxin Metabolism.

Article -
Cephalothrix simula, a new, non-native, invasive, highly toxic species of nemertean worm in the United Kingdom by David Fenwick 20.12.18.

Cephalothrix simula was first found in the UK by David Fenwick at Godrevy Point, nr. Hayle, Cornwall, on the 18th May 2018. Two mature specimens were found under a mussel valve that was stuck to the bottom of a rock that was in a pool below the mean low tide level. The species originates from Japan frequently being reported around the coast of Kyusyu. The species was likely brought to Europe in the ballast water from vessels visiting ports or as a result of the importation of live oysters from the Far East for commercial culture, as with the Portuguese Oyster, Magallana gigas. Cephalothrix simula was first found in the colder waters of Northern Europe by Marco Faasse, a Dutch marine biologist, in Holland in 2014. The site of first introduction into Europe is not known but records suggest the species has spread from the south to the north, the species could have been spreading around Europe for many years before it was discovered. The species is currently known from Italy, Holland, Spain, France and now England. Agencies in Ireland, Wales and Scotland have been alerted to find in England, but the threat of human contact / interaction is deemed low and their is no cause or case for alarm, although further research is needed to confirm this, and the ecology of the toxin producing bacteria this ribbon worm contains needs to be determined as does the spread of the species in the UK.

There is scant evidence on which to base a hypothesis but what evidence there is points to the species arriving in the UK by two potential mechanisms, one natural, the other anthropogenic, by man. It is likely that Cephalothrix simula arrived at Godrevy Point, on the north coast of Cornwall via natural sea currents that cross Biscay from Spain, the nemertean has already been found on the Atlantic coast of France and Spain. One such current, the Rennell Current, it is a current more famous and responsible for wrecking sailing ships on the Isles of Scilly than it is for bringing non-native and southern species to our coast and the south coast of Ireland, but numerous new southern species have been found in recent years in West Cornwall, four of these have been nemerteans that are more at home in north-west Spain.

In September 2018 Cephalothrix simula was found by David Fenwick in Poole Harbour, Dorset. The species has also been detected by Southampton University at Southampton., the species being found at Southampton in small samples of seawater using new eDNA techniques that were used to detect the presence of a number of non-native species. It is probably more likely that either shipping, via ballast water, or the commercial importation of shellfish brought the non-native to ports and harbours on the south coast of the United Kingdom. Indeed, harbours across southern England might have been the initial places where the ribbon worm was first brought to the UK. It is also possible that Cephalothrix simula was brought to Europe multiple times by a number of means.

What is sadly rather lacking is its late detection as the species appears to be quite established where it has been found. There are numerous reasons for this but the main one is that the recording of wildlife has largely been left to a dedicated number of volunteers in the UK, who make up a tiny fraction of the population., few specialize in marine invertebrates, and those who have an interest in groups like nemertea can quite literally be counted on one hand. Of course in the majority of cases if something becomes established in the sea there is very little we can do about it, unless the detection of the species is 'really early', and this is what makes the use of eDNA techniques so valuable for the future as non-native invasive species can have both an economic as well as an environmental impact.

Cephalothrix simula is a highly toxic species of nemertean or ribbon worm which contains a toxin known as tetrodotoxin or TTX, it is also referred to as Pufferfish neurotoxin. TTX is a highly potent neurotoxin and the most toxic marine toxin known to man and is a thousand times more potent than cyanide, and there is no know cure. On finding the species the worms were briefly handled, luckily with no ill-effect, but it is not recommended for another related species, Cephalothrix linearis, a native to the UK, was found to release TTX through its body during a study of the species in Japan where it is also found. The species could therefore use TTX to defend itself, and to kill prey, and in the same manner a snake or spider would use venom. It is not known whether or not Cephalothrix linearis produces TTX in its body in the UK, this is currently being investigated, but it is possibly quite likely where populations of C. linearis and C. simula may occur together.

Cephalothrix simula is not the only species that can contain TTX neurotoxin as Pufferfish, Ocean Sunfish, Triggerfish, Blue-ringed Octopus, some Moon Snails and Furrow Crabs, and also some planktonic organisms called dinoflagellates can contain the toxin, there are also numerous other groups and species that can also contain the toxin. According to one source an Oceanic Pufferfish washed-up on Chesil Beach was tested for TTX and was found to contain no TTX at all, yet there are continual and almost annual reports in the press under headings like "Toxic killer fish washed-up on beach". TTX is usually produced by certain species of bacteria, they include certain species of Actinomyces, Aeromonas, Alteromonas, Bacillus, Pseudomonas and Vibrio bacteria, and these bacteria may enter higher organisms through the food chain, so if a species feeds on something that does not have TTX then it is unlikely to accumulate it. Vibrio bacteria was briefly mentioned in a program about marine plastic on the BBC, and Vibrio bacteria was noted as being responsible for killing coral reefs in the South China Sea, the bacteria being transported to the reef by plastic refuse. In Japan Pufferfish are known to feed on Cephalothrix simula, the fish is known for its high toxicity, but the fish is also a traditional delicacy, referred to as 'fugu', the consumption of the fish has been responsible for causing numerous deaths in Japan and elsewhere, on an annual basis. Pufferfish are banned from sale or import in many countries because of the risk of ingesting lethal amounts of tetrodotoxin. There are numerous cases of tetrodotoxin poisoning from the USA, and these relate to the ingestion of contaminated fish of the Pufferfish family.

The overall threat is from the bacteria that produces the toxin and not necessarily from the host organism itself, the amount of toxin produced can be very variable and much depends on the organisms on which the host species had been feeding and what the temperature is. This is why there is a need to study the presence of bacteria and levels of TTX in host organisms in the UK, and to look for toxicity within the food chain to see where the bacteria may be passed, to what species, and in any species what organs are responsible for storing the highest concentrations, such as the liver with the Pufferfish, and of course if found in a commercially eaten species, are the levels within safe limits? There is so much research to do in the UK but the primary research will focus on food safety, but given the worm has likely been here a while already, the initial thinking is that this is 'not' something we have to panic about as no instances of seafood contamination have been found that might damage human health and toxin testing has been undertaken by the government for years before the find of C. simula . Despite the negative issues that surround TTX, the toxin may have uses as an analgesic for use with acute and neuropathic pain.

Godrevy Point is a Special Site of Scientific Interest or SSSI, foraging of shellfish is not allowed, but sadly the rules are frequently ignored, so it became important to test shellfish for TTX now that C. simula had been found. Godrevy Point is owned by the National Trust, who gave permission to collect approx. 50g of meat per species of molluscs and crab species, the search was limited to within a 10-20m diameter area from where Cephalothrix simula was first found. CEFAS Weymouth detected no measurable amount of TTX in any of the shellfish species provided, which included crabs, mussels, winkles and limpets. Whilst the level of TTX in shellfish at Godrevy Point as of October 2018 is zero, this does not mean that the level will stay at zero, it could rise with ocean warming or increase as the local populations of the worm increase. Elsewhere a seasonal increase in toxicity has been noted, and summer months are known for the highest toxin levels.

The ribbon worm Cephalothrix simula cannot physically wound a human, it is too small and it does not have the mouthparts to do so, but it is possible for the neurotoxin contained in the worm to be absorbed through broken skin or by ingestion. TTX cannot be destroyed by heat such as that used for cooking e.g. on cooking shellfish. Care is needed when coming into contact with this species, and my advice is not to handle it, far simpler to look at specimens by picking them up carefully using a piece of stiff seaweed such as Saw Wrack etc., then if they are to be collected for identification, the seaweed and the worm can be placed in a tube together and to reduce handling. There is a slightly increased chance of coming across this species if you are a marine life recorder or visit shores during organized events, as people / parties are more focussed on looking for wildlife. In general people visiting the shore who do not know what the species looks like will probably not even notice it's there because of how small it is. Cephalothrix simula has not been found on any of the tourist beaches in Cornwall, it has only ever been found at one headland site in Cornwall during an extra low spring tide.

At the present time there is an extremely low risk of human interaction but the risk may increase as new sites for the species are found, the site at Poole is very close to habitation, but this is no cause for concern. Now the species has been found it can be studied by some of the top scientists in the world, and research can be conducted on the affect the species could have on public health and the natural environment. Of course, people in many countries around the world live with poisonous or venomous animals, here in the UK we already live alongside Adders and potentially lethal plants and fungi, and of course we also have to deal with potentially lethal antibiotic resistant strains of bacteria. Perhaps we should remind ourselves of these before shouting too loudly about Cepthalothrix simula, as it's just another species on a fairly long list of toxic organisms that can be found in the UK, although weight for weight, none of these contain a neurotoxin so potent, where no cure is available. This species could therefore represent the most toxic species to be found in the UK.

Future reporting and scientific studies will be all empowering and allow us to make decisions and policy about how we live with any threat posed. At the present time the species has only been found at a very limited number of locations and only on the lowest tides so the general public are not likely to come across it, and rather importantly neither are their pets. The worm does not swim, it lives on the bottom so there is no risk to swimmers. The species does not occur in freshwater.

Toxin testing in shellfish is something that has regularly been done in the past for reasons of food safety and shellfish offered for sale from registered British producers is SAFE. However, the only shellfish that is tested is that from licensed collectors / farms / harvesting sites. Unfortunately, not all shellfish is collected legally and if the trade in illegal shellfish is not prevented there remain a risk to public health because of the lack of safety testing. Sometimes gangs of Eastern Europeans are used to illegally pick shellfish from shores, including marine protected areas (e.g. limpet picking from Cornish shores). This practice has to be stopped as it could prove a significant risk to health and the environment. Similarly there could be a risk with personally foraged seafood as it has not been established where C. simula occurs in the UK, the toxin levels in shellfish, if any, could conceivably vary depending on the local ecology or frequency of Cephalothrix simula, but there are currently 'many' unknowns because research is at such an early stage. There is a need to be cautious and a need to be sure about how this species could affect our health and the environment, and the potential mechanisms involved, e.g. where TTX could end up in the food chain.

Further information on the toxicity and bacteriology of this species can be found in a paper published 'Marine Drugs' by CEFAS Weymouth, "New invasive nemertean species (Cepthalothrix simula) in England with high levels of tetrodotoxin and a microbiome linked to toxin metabolism" by Andrew D. Turner, David Fenwick, Andy Powell, Monika Dhanji-Rapkova, Charlotte Ford, Robert G. Hatfield, Andres Santos, Jaime Martinez-Urtaza, Tim P. Bean, Craig Baker-Austin and Paul Stebbing. Published: 16 November 2018 in Marine Drugs 16(11), 452; doi:10.3390/md16110452.

Cephalothix simula can only be identified using a DNA test, but there exists a need to report specimens that are likely C. simula as "Cephalothrix sp. (cf. Cephalothrix simula)" after being identification / verification by an expert, and where DNA testing may not be immediately possible or possible; and so to assess the potential UK distribution of this invasive non-native toxic species in the UK.

The author of this artical, David Fenwick, will be willing to verify reports of possible Cephalothrix sp. (cf. Cephalothrix simula) from good images and a small report relating to habitat, at no expense to the recorder / finder. It may not be possible to physically follow up all the records received because of the cost of DNA analysis and travel costs but if specimens are sent to David Fenwick in seawater in screw topped sealed tubes he will endeavour to verify what the species is and get it analysed if he thinks the specimen/s are likely to be Cephalothrix simula and especially if they come from a part of the UK where there is no previous record of Cephalothrix simula.

For DNA analysis specimens must be cleaned in filtered seawater and fixed in >95% ethanol. Sadly this will prohibit many wildlife recorders from providing specimens for DNA testing, but reports will be of interest to local regional bodies such as universities and other agencies, and some of these may be able to offer DNA testing or assist in following up on any local find.

To conclude, it is hoped that DEFRA, Food Standards Agency and Public Health England will fund further research into Cephalothrix simula and into the bacteria that produce this dangerous neurotoxin. Research needs to be done at a pace to catch-up on the UK distribution of the nemertean, but long term monitoring is needed because of seawater warming because of climate change, as there is a proven increase of toxicity with temperature. There is also a need to look at the toxicity of our own native species of nemerteans and ensure toxicity is not being passed to them now C. simula is here. There appears to be a need to regulate illegal shellfish collection and distribution, and report on the safety of foraged shellfish from shores in England and elsewhere.

To date there have been no instances of TTX poisoning in the UK. 'ALL' shellfish must be presumed safe to eat, but now Cephalothrix simula is here we will need to ensure that all shellfish remains safe to eat. It must be noted that there are other toxins that naturally occur in the UK and some of these can be the cause of shellfish poisoning and make people feel quite unwell. Of course, and despite the very low risk, there is also a need for the government to alert medical establishments / NHS about the potential of tetrodotoxin poisoning and its symptoms.

Further reading:
New Invasive Nemertean Species (Cephalothrix simula) in England with High Levels of Tetrodotoxin and a Microbiome Linked to Toxin Metabolism.
Andrew D. Turner, David Fenwick, Andy Powell, Monika Dhanji-Rapkova, Charlotte Ford, Robert G. Hatfield, Andres Santos, Jaime Martinez-Urtaza, Tim P. Bean, Craig Baker-Austin and Paul Stebbing.

Potential Threats Posed by Tetrodotoxins in UK
Waters: Examination of Detection Methodology Used in Their Control
Andrew D. Turner, Cowan Higgins, Wendy Higman and James Hungerford
Published: 11 December 2015

Detection of the pufferfish toxin tetrodotoxin in European bivalves, England, 2013 to 2014
A D Turner, A Powell, A Schofield, D N Lees, C Baker-Austin

Vibrio alginolyticus in the U.K.
Laceration / infection gained while swimming in Cornwall in 1976
Hartley 1991
The above paper has been placed here for medical reasons. Cephalothrix simula will likely spread up the north coast of Cornwall and warm years like 1976 may increase the risk of infection. It must be noted that this 1976 report is the only report of this infection that I have found from Cornwall so the risk of infection remains incredibly low. The report shows how to treat infections and the antibiotics used and GPs and Public Health England should be aware of the higher risks if someone is injured or infected close to a Cephalothrix simula colony where it must be presumed that there will be an increased likelihood of infection, even though the risk is small. It must also be noted that the V. alginolyticus bacteria occurs all around our coastline and is also associated with species other than Cephalothrix simula.

The risks posed by this species may be low BUT they are likely to increase with global warming. This is what now clearly must be asked and become public knowledge.

1/ What is being done to determine the distribution of Cephalothrix simula around the UK? Nothing???

2/ What and how many commercially important inshore shellfish producing areas are being monitored around the UK and how often are they being monitored? Are oyster fisheries of particular risk given oysters are often eaten raw?

3/ Has the Health Protection Agency circulated details of TTX poisoning and methods of treatment around the NHS. Are Vibrio bacteria tests included in marine bathing water safety tests. Are NHS detection methods robust and used enough? Are Vibrio infections notifiable infections, if not why not?

4/ Has the Food Standards Agency made Council Environmental Health Departments aware of Cephalothrix simula and the risk posed by TTX? Can we see the literature?

5/ Have the Royal College of Veterinary Surgeons and British Veterinary Association been informed about Cephalothrix simula as an intertidal species and the risk TTX poses to domestic animals and other wildlife?

APHOTOMARINE

An educational resource dedicated mainly to the photography
and diversity of marine life that can be found in coastal waters
and intertidal areas of Great Britain and Ireland by David Fenwick.

APHOTOMARINE

An educational resource dedicated mainly to the photography and diversity of marine life that can be found in coastal waters and intertidal areas of Great Britain and Ireland by David Fenwick.

An educational resource dedicated mainly to the photography
and diversity of marine life that can be found in coastal waters
and intertidal areas of Great Britain and Ireland by David Fenwick.