John dory: curious and cosmopolitan fish

Zeus faber, Porthkerris, UK (montage)

I was diving at Porthkerris (Cornwall, United Kingdom), getting cold and running out of air. Just when I decided to swim back to the beach, I saw from the corner of my eye something whitish swimming along with me. When I turned my head I saw my first John dory, Zeus faber (NL: zonnevis)(specimen 1). I had already heard they were seen by divers and I would love to see this peculiar and exotic looking fish. But I had decided not to search for them, because it would take a lot of time (needle in a haystack) and their were so many other beautiful things to see.

Zeus faber, Porthkerris, UK (specimen 1)

At first we were looking at each other and when I slowed finning the John dory kept pace. It was about 30 cm long. I started taking photo’s. I had to try to come as close as can be, because I had a fisheye lens fixed on my camera. So after a few photo’s I decided to slowly advance to the John dory. As I expected it swam away, but then it eased. I had another try; this repeated for a while and at last I could come as close as 50 cm.

Zeus faber, Porthkerris, UK (specimen 2)

I was amazed: this John dory was not afraid at all and curious, because if it had decided to disappear it would have been easy. They are quite compressed and swimming through the underwater forest of cuvie, Laminaria hyperborea (NL: groot vingerwier), as you can see in the photo above and below, it would have (dis)appeared as a loose stalk of this seaweed.

What avoked this curiosity? At first it could not have been the reflection of itself in the domeport of my underwater equipment - a suggestion often made - because it swam alongside. With a lot of anthropomorphizing and judging by its 'haughty' looks (due to its big mouth with steeply-angled jaws) it could have thought: what is this stranger doing on my property? I noticed it chasing other fish away. I just don’t know and it doesn’t matter. I had a perfect encounter for almost 10 minutes and some nice photo’s.

Zeus faber, Porthkerris, UK (specimen 1)

As you have read the story so far and my former posts, you may wonder if I have forgotten the promised posts about Botanical Beach and other items of Vancouver Island's fauna. I haven't but for now I am switching to the fauna and flora of the UK and especially of Porthkerris. In one of my next posts I will describe and show this excellent diving spot (and dive centre) in the southwest tip of England.

I had 16 dives at Porthkerris in the period of 31 August to 13 September; 7 last year and 9 this year. The described encounter with the John dory was my penultimate dive last year and I was happy to meet them again this year. And not just one but at least 7 (I photographed 4 specimens; my dive buddy Ruud 3). Just as last year they seemed to appear out of nowhere. They were of the same size as the one I saw last year and a few were smaller.

Zeus faber, Porthkerris, UK (specimen 1)

My first John dory (specimen 1) looked quite pale, hence my remark 'something whitish swimming along'. But John dories can be very colourfull. Especially specimen 3 with its golden glow (photo below). Their is discussion regarding the origin of its common name, but in French 'jaune dorée' means yellow gold. Not far-fetched.

If you have a good look at my photo's you can see that the pattern on their sides is unique. Just like an enlarged thumbprint. I wondered if I had seen the same specimens on different days and years. I compared all the photographed fish, eight in total, and they were all different specimens (hence the reason for making notice of 'specimen 1' etc.). For comparison you must have photo's of the same side, because the pattern on both sides of a specimen is not identical!

Zeus faber, Porthkerris, UK (specimen 3)

But what if they can change their pattern? A lot of fish species like blennies, gobies and for instance plaice, are able to change, recede or intensify their colour and their colour pattern to blend in with the environment. John dories are able to adapt their colour (saturation) to their surroundings: I saw the pale(r) ones in open water or hovering above seaweeds; the more colourfull specimens were swimming in front of rocks or in darker spots. But that is not the same as changing pattern.

I came upon a remarkable story by Dan Bolt - 'Babbacombe's cleaning stations' - about a cleaning station serviced by Leach’s spider crabs, Inachus phalangium (NL: gladde sponspootkrab) which John dories visit to get rid of small parasites (not the ones you can see with your naked eye). He writes: 'Spending so much time in one small area it becomes easy to recognise individual animals because of the unique markings these fish have on their body.'

Inachus phalangium, Pointe de Trévignon, Brittany, France

I asked Dan if he knew more about changing pattern. He replied: 'In short, no I am not sure that they can not change their pattern. The observation period for the cleaning behaviour was relatively short; about 8 weeks in all, and certainly in that time-scale I could recognise individuals by their patterning. But observing only for 8 weeks does not proove that they do not change their patterns throughout the year. Certainly they can make their colour fade or more bold, but sadly I can't give you a definitive answer about changing patterns.'

Zeus faber, Porthkerris, UK (specimen 4)

You must have noticed the dark spot with its light margin in the centre of each flank. It is supposed to have the effect of an eye i.e. to confuse its prey and predators. In legend these are St Peter’s fingerprints, left when he took a coin from the fish’s mouth to pay up his tax. Hence its popular name in a lot of countries referring to St Peter: Sankt Petersfisch in German, Saint-Pierre in French, St. Pietersvis in Dutch etc. It could also explain the name John dory: St Peter is the gatekeeper in heaven, in Italian 'janitore'.

© FishBase

Distribution map of Zeus faber. Except for the America's the John dory is a cosmopolitan. It is remarkable that it thrives in cold and tropical waters.

John dories are solitary fish. They live in a depth of a few meters deep to 200 meters (Lythgoe, J. & G., 1976). Edgar (1997): 'depth 1-170 m; it occurs most abundantly in deep offshore waters, although individuals occasionally enter shallow water estuaries' (describing species of the Australian coasts). Heemstra (2004): 'adults in 50-400 m' (species of South-Africa), so even 200 m deeper.
According to most authors John dories can be found in sand-, reef- and kelp-habitats or a mix of these and are often catched by trawlers above sandy bottoms.

Wheeler (1975): 'A very similar species, Zeus japonicus, is found in the Indo-Pacific. The two scarcely differ morphologically.'

Zeus faber, Porthkerris, UK (specimen 3)

As you can see, they have a laterally compressed shape with a long dorsal fin - composed of long, strong fin spines - and oversized pelvic fins. As said, it makes them hard to spot in kelp forests. You can often observe them tilted at all sorts of angles and even upside down (Naylor, 2011)! Have a look here at a short video.

Sharlin cruiser (left © archangel72367, right © babylon5.wikia.com)

As a big fan of the science fiction series Babylon 5, they remind me of a 'sharlin cruiser': laterally compressed with oversized wings. Who is to know the artist wasn't inspired bij John dories?

Zeus faber, Porthkerris, UK (specimen 3)

Muus (1966) reports an average length of 25-30 cm and at that size it has a weight of 2 kg, but up to 60 cm and 8 kg; Allen (1999) up to 75 cm and Debelius (1998) and Heemstra (2004) even 90 cm! A bit scary at this size coming out of the blue… Heemstra (2004): 'females grow larger than males.'
According to Janssen (1979) who has studied John dories in the Netherlands from 1960 to 1977, they are 15 to 28 cm after two years and 29 to 42 cm in their third to fourth year. Heemstra (2004) reports a lifespan of 15 years for females and 13 years for males.

Duncker (1960) estimates first sexual maturation of males at 25–28 cm, and females at 34–38 cm. They spawn in summer at the south coast of England at a depth of less than 100 m. In the Mediterranean, in warmer waters, they spawn in spring (Muus, 1966). The southern North Sea is to shallow as a breeding ground (Nijssen & De Groot, 1987). The eggs are pelagic (Muus, 1966). 

Zeus faber, Porthkerris, UK (specimen 3)

John dories are clumsy swimmers. So it has to depend on stealth and its big protrusile mouth (have a look here), which enables it to suck in a large volume of water with unsuspecting prey. Unfortunately I have never seen them catching prey.

It seems fish is their main diet, but Nijssen & De Groot (1987) mention that, apart from fish, crustaceans and cephalopods have been found in their stomach.

Predated species of fish in northwest Europe according to Muus (1966), Naylor (2011) and Nijssen & De Groot (1987) are herring, Clupea harengus (NL: haring), pilchard, Sardina pilchardus (NL: sardien), sprat, Sprattus sprattus (NL: sprot), sand smelt, Atherina presbyter (NL: koornaarvis), horse mackerel, Trachurus trachurus (NL: horsmakreel), sand eel, Ammodytes species (NL: zandspiering), gobies, Gobiidae (NL: grondelsoorten) and more specific two spot gobies, Gobiusculus flavescens (NL: Ruthenspars grondel).

Gobiusculus flavescens, Porthkerris, UK

Two spot gobies were very abundant at Porthkerris as you can see in the photo above. Here, I guess, this species is John dories staple food. 

Gobiusculus flavescens, St John's Point, Ireland

Two spot gobies are about 6 cm long, but often much smaller. They are, contrary to most other gobies species, not bottom dwelling but demersal fish. Only when the water is getting cold, they will rest on the bottom.

Gobiusculus flavescens, 't Koepeltje, Grevelingen, The Netherlands

At first view two spot gobies look like 'innocent' guppies. But have a look at their teeth!

Zeus faber, Porthkerris, UK (specimen 2)

A John dory with some two spotted gobies and, at the top, pollack, Pollachius pollachius (NL: pollak). Pollack are also preying on two spotted gobies.

Caligus species on Zeus faber, Porthkerris, UK (specimen 1)

Almost every John dory at Porthkerris was infected by sealice, one of the many Caligus species. I asked marine biologist 'universalis' Marco Faasse of eCoast Marine Research, Belgium, if he could identify the specie(s). Marco: 'Two species of Caligus are known on John dories: Caligus elongatus Nordmann and Caligus zei. Maybe both species are visible on your photo, because I see two rather different parasites. However, I won't rule out it is the same species, only a different sex.'

unknown flatworm(?) species on Zeus faber, Porthkerris, UK (specimen 4)

Specimen 4 was not infected bij Caligus but other, smaller parasites. Marco: 'I presume these are parasitic flatworms of the class of Monogenea. I  have found the flatworm Udonella caligorum on Caligus elongatus on the lumpsucker, Cyclopterus lumpus (NL: snotolf). This flatworm settles itself on sealice, but it is feeding on the mucus secreted by the skin of the fish. See article in Het Zeepaard 2005(4). The specimens on your photo could be a related species. However, searching for flatworms (there is an incredible amount of species of worms) related to Zeus faber I could only find worms living in its digestive system.'

unknown flatworm(?) species on Zeus faber, Porthkerris, UK (specimen 4)

I want to thank Dan Bolt for his reply, Marco Faasse for providing information about the parasites and Godfried van Moorsel for supplying an article about changing colour in rockpool gobies.  

Literature:

• Debelius, H., 1998. Vissengids Middellandse Zee en Atlantische Oceaan.
• Duncker, G. 1960. Die Fische der Nordmark. De Gruyter & Co., Hamburg.
• Edgar, G.J., 1997. Australian Marine Life. 
• Faasse, M., 2005. De snotolf een dierentuin: over Caligus elongatus (Copepoda) en Udonella caligorum (Platyhelminthes, Monogenea). Het Zeepaard 65(4): 123-127.
• Heemstra, P. & E., 2004. Coastal fishes of Southern Africa. 
• Janssen, G.M., 1979. The occurence of Zeus faber in the coastal waters of the Netherlands. Bull. Zool. Mus. Univ. Amsterdam, 6 (20): 153-158.
• Lythgoe, J. & G., 1976. Vissen van de Europese kustwateren en de Middellandse Zee. 
• Muus, B.J., 1966. Zeevissengids.
• Naylor, P., 2011. Great British marine animals. 
• Nijssen, H. & S.J. de Groot, 1987. De vissen van Nederland. 
• Wheeler, A., 1975. Fishes of the world.

Websites:

• Australian Museum - John Dory
• Dan Bolt Earth in Focus - 'Babbacombe's cleaning stations' 
• FishBase, Froese, R. and D. Pauly. Editors. 2014. World Wide Web electronic publication.
• FAO Fisheries and Aquaculture Department - Species fact sheets - Zeus faber
• Giuseppe Mazza - Scientific photographer - Zeus faber
• Sealice Explorer
• Wikipedia 

Colourful sea anemones and other extraordinary Cnidaria of Vancouver Island

Pachycerianthus fimbriatus, Rock Bay, Canada

In this post I present a few animals belonging to the Cnidaria I found at Vancouver Island, Canada. Apart from the last two species they all belong to the subclass Anthozoa, literally flower animals: the sea anemones (NL: bloemdieren, zeeanemonen).

Urticina grebelnyi, Rock Bay, Canada

Let's start with one of my favourite photo's of the painted anemone, Urticina grebelnyi. I love Urticina species (dahlia anemones, NL: zeedahlia's) with their stout tentacles. Up to 25 cm in diameter and 20 cm high. This small specimen was attached to the jetty at Rock Bay.

Urticina grebelnyi, Cottam Point, Canada

Never heard of Urticina grebelnyi? Neither did I. But the Urticina specimens I photographed looked rather different, so I searched the internet and came upon the website Actiniaria.com of Nadya and Karen Sanamyan (Kamchatka Branch of Pacific Institute of Geography, Russia). It seemed that what I thought were Urticina crassicornis, were not.

Urticina grebelnyi, Deep Cove Bay, Canada

From Actiniaria.com: 'This common North Pacific species often is called painted anemone or Christmas anemone and erroneously identified as Urticina crassicornis. Actually, true Urticina crassicornis is a very different species having absolutely smooth body, while in painted anemone - Urticina grebelnyi - the whole column (body) is covered by numerous nonadhesive vesicles. According to a recent revision of Urticina, the valid name of painted anemone is Urticina grebelnyi.'

Urticina grebelnyi, Rock Bay, Canada

A rather dull coloured/patterned painted anemone.

I asked Nadya and Karen Sanamyan for help. In a very prompt reaction Karen told me all my photo's regarded Urticina grebelnyi, except for one (see further). 

Urticina grebelnyi, Deep Cove Bay, Canada (same specimen as photo below)

Karen Sanamyan: 'I never saw colourless specimens of U. grebelnyi before as on your images, but I nevertheless have no doubt it is this species. The overall habitus is characteristic and a row of white-pearl spherules on the margin is characteristic.' See the band of white markings just below its tentacles (or above, just how you are looking) at the next photo.

Urticina grebelnyi, Deep Cove Bay, Canada

The painted anemones I photographed at Deep Cove Bay were attached to a jetty. Click here for a post about Deep Cove Bay.

Sea anemones are carnivores. Usually the anemones with fewer, more stout tentacles - like the Urticinidae - are the most 'sticky' ones, i.e. the sea anemones with the more potent or plentiful nematocyst (the stinging cells).

Urticina grebelnyi, Cottam Point, Canada

A gorgeous coloured specimen of the painted anemone. Below in detail with partly opened mouth. As you have seen by now, there is a lot of variety in colour and pattern in this species.

Urticina grebelnyi, Cottam Point, Canada

Urticina species, Rock Bay, Canada

This is the odd one out. Karen Sanamyan: 'I can not say to which species this one belongs. It is hexamerous and white bands on the tentacles are arranged in a different way in comparison with Urticina grebelnyi.' 

Cribrinopsis fernaldi, Rock Bay, Canada

I found the next species of this post, Cribrinopsis fernaldi, the crimson anemone, on sandy bottom at Rock Bay; the same biotope as the forthcoming tube-dwelling anemone. I can't recall if it was attached to a rock(s) or shell fragments, but I suppose it must be, otherwise it will drift with upcoming tide to the shore. Up to 30 cm tall.

Cribrinopsis fernaldi, Rock Bay, Canada

Detail with partly opened mouth. The common name is - as is often the case - dull and not very characteristic. What about 'magma anemone'.

Cribrinopsis fernaldi, Rock Bay, Canada

unidentified species, Rock Bay, Canada

This small white anemone is unidentified. It is about 10 mm in diameter. I found towards 10 specimens attached to the jetty at Rock Bay, next to some tube-dwelling worms (click here for the tube-dwelling worms post; in this post you can see another specimen of the white anemone).

unidentified species, Rock Bay, Canada

I asked a few specialists for identification. I wrote Daphne Fautin (Professor Ecology and Evolutionary Biology, University of Kansas, USA). Part of her answer: 'I have never seen an animal such as in your photo. This is lovely! But I could not even venture a family without examining the internal anatomy and nematocysts of the animal you photographed.' Before I forget: have a look at her website Hexacorallians of the World.
Karen Sanamyan wrote: 'Most probably a species of the family Sagartiidae'. 

Pachycerianthus fimbriatus, Rock Bay, Canada

The tube-dwelling anemone, Pachycerianthus fimbriatus (also figuring in the first photo of this post), is a very different kind of sea anemone.

Pachycerianthus fimbriatus, Rock Bay, Canada

It lives buried in the ground in a self made tube of mucus, sand and mud. When disturbed it retracts itself with quite some speed in its tube; an excellent way of protection. It has no adhesive foot like 'normal' sea anemones. The tube-dwelling anemone is a beautiful monster: the tentacle crown grows up to 30 cm across, the tube up to 1 m long.

tube of Cerianthus lloydii, Strangford Lough, near wreck Inner Lees, Northern Ireland

As examples of the tube: the top of the tube of another Cerianthid: Cerianthus lloydii, lesser cylinder-anemone (NL: viltkokeranemoon) and below the same species with the tube lying uncovered on the sandy bottom (probably because of a storm as we found several uncovered specimens that day).

Cerianthus lloydii, Zeelandbrug, The Netherlands

Pachycerianthus fimbriatus, Rock Bay, Canada

Another differentiating feature are the tentacles. Wikipedia: 'Cerianthids have a crown of tentacles that consists of two whorls of distinctly different sized tentacles. The outer whorl consists of large tentacles that extend outwards. These tentacles taper to points and are mostly used in food capture and defence. The smaller inner tentacles are held more erect than the larger lateral tentacles and are used for food manipulation and ingestion.'

Seascape at Rock Bay, Canada

It was abundant at Rock Bay: I noted 'towards 100 specimens'.

Pachycerianthus fimbriatus, Rock Bay, Canada

And then the tide came in… The top of its tentacles moving like banners in the wind. The same Pachycerianthus, just another colour variety. Cerianthid species are hard to distinguish. Distribution, length and colour(pattern) - especially the combination of these elements - are differentiating features. But to be really sure, as mentioned with the unidentified white anemone, you have to collect the specimen and dissect it, to examen its nematocysts and internal morphology.

Cerianthus lloydii, Stavenisse, The Netherlands

Colour is always a tricky characteristic. The first time I saw a white Cerianthus lloydii like the one above, I thought it was another species. Sometimes it is easy because there are no other relatives, as is the case with the Cerianthids at Vancouver Island and in the Netherlands. But only until the moment someone collects and examines a few and finds a different species!

This is a cropped version of the first photo of this post. When I enlarged the photo on my computer screen, I saw a few Amphipod, sea flea species, on the tentacles. Remarkable that these crustaceans are not devoured by Pachycerianthus. Are they too small, just morsels? Or are they immune for the nematocyst - the stinging cells - of the anemone? Are they parasites or commensals?

Amphiprion frenatus & Heteractis magnifica, Kandooma, Maldives

I know of and have seen the symbiotic relationship between anemone fish and sea anemones, like the tomato clownfish, Amphiprion frenatus and the magnificent sea anemone, Heteractis magnifica. Wikipedia: 'The mucus coating of the fish may be based on sugars rather than proteins. This would mean that anemones fail to recognize the fish as a potential food source and do not fire their nematocysts.'

I asked marine biologist Marco Faasse (eCoast Marine Research, Belgium) if he knew of the association between Pachycerianthus and these Amphipods: 'Associations of certain crustaceans with anemones are fairly common. They derive their immunity in some cases, just like anemone fish do. It is also known of certain Amphipods. I do not know of associations of Amphipods with Cerianthids, but maybe you can find them in literature. Interesting to find out if this specific association is known. Would be nice if you find something new. But then you have to go back to collect those Amphipods….'

Inachus phalangium in Anemonia sulcata, Porthkerris, United Kingdom

Closer to home: Inachus phalangium, Leach's spider crab (NL: gladde sponspootkrab) is often found in the tentacles or clasping the column of Anemonia sulcata, the snakelocks anemone (NL: wasroos). Excellent protection for the spider crab against predators, just like it is for anemone fish.

About protection from stinging cells in liveaquaria.com: 'The glass anemone shrimp is protected from the stinging cells of the anemone by the mucus secreted by the anemone, which coats the shrimp's body. Every time the shrimp molts to grow, it has to hide from the anemone since it loses its mucus-covered shell. It then has to slowly approach the anemone and re-cover its body with the mucus.'


What about other well known sea anemones of Vancouver Island as the green surf anemone, Anthopleura xanthogrammica, the pink-tipped anemone, Anthopleura elegantissima and the giant plumose anemone, Metridium farcimen? I already posted about these anemones in 2008 (see the link in the aforementioned scientific name).

Balanophyllia elegans, Neck Point, Canada

The only hard coral I found: orange cup coral, Balanophyllia elegans. Not to be confused with, what is also called orange cup coral: Tubastraea coccinea, a tropical species. That is why I always mention scientific names. Up to 2.5 cm across and 1 cm tall.

Balanophyllia elegans, Neck Point, Canada

As you can see Balanophyllia are solitary corals. Meinkoth (1981) about their colour: 'Its orange colour is a fluorescent pigment and even at depths of 9 m or more, where red light is lacking, it shows the same bright hue.'

Ptilosarcus gurneyi, Cottam Point, Canada

It was my first dive at Vancouver Island and I did not expect to find this extraordinary animal looking like a hair brush: the orange sea pen, Ptilosarcus gurneyi. Let alone in such shallow water (12 m deep at low tide). But Friese (1972) describes: 'L. gurneyi is sometimes found inter tidally, but more often below the low tide level.'

Sea pens are not attached to a substrate. Instead their 'foot', the peduncle, is thrust into soft bottom. It then expands the lowest part of its foot to work like an anchor.

Ptilosarcus gurneyi, Cottam Point, Canada

I found up to five specimens of this Octocorallian. Up to 48 cm high and 10 cm wide; the specimens I saw were up to 25 cm high.

Ptilosarcus gurneyi, Cottam Point, Canada

Rather than being an individual animal, a sea feather is a colony of polyps.

Sometimes a bit of foreknowledge would have been nice: 'Try gently stroking one of these colonies on a night dive, then turn out your light. Presto - a 'natural' blue-green cyalume stick!' (Lamb & Hanby, 2005). It was dark enough at 12 m deep (heavily overcast and milky water)...

The next two species belong to the subclass Medusozoa. 

Hydractinia species & Pagurus armatus, Cottam Point, Canada

Another colony of Cnidarians, but not directly related to sea anemones, corals and sea pens. Snail fur hydroid, Hydractinia species (NL: zeerasp soort) belongs to the class of Hydrozoa. Snail fur species attach themself to snails occupied by hermit crabs, like this black-eyed hermit crab, Pagurus armatus. Snail fur takes advantage of the mess hermit crabs create while eating: food for free and easy pickings.

Hydractinia species & Pagurus armatus, Cottam Point, Canada

In this further cropped photo you can easily distinguish the individual polyps of the colony. 

Aequorea species, Rock Bay, Canada

Looking very different from the previous species, but also a hydroid: Aequorea species, water jelly species (NL: soort lampekapje). Up to 17.5 cm across.

Aequorea species, Rock Bay, Canada

Aequorea belong to a group of hydroids, which start their life as larva, develop into a polyp (something like the aforementioned snail fur) and then change - for a short period of their life - into a hydromeduse, a kind of jellyfish (which they are not). The hydromeduse develops larvae and so on. Of Aequorea species little is known. Of some species marine biologists are not sure if a certain polyp (usually with a different scientific name!) really is a stage of that Aequorea. The only means is breeding larvae into polyps into hydromedusae and so on. But that appears very difficult. As you can imagine: something out of my amateur reach.

I thank Karen Sanamyan and Daphne Fautin for their help in identifying some sea anemones and Marco Faasse for his comment on the Amphipod association.

References:

• Actiniaria.com (the website of Karen and Nadya Sanamyan)
• Friese, U.E., 1972. Sea anemones.
• Lamb, A. & B. Hanby, 2005. Marine Life of the Pacific Northwest. 
• Liveaquaria
• Meinkoth, N.A., 1981. The Audubon Society Field Guide to North American Seashore Creatures.
• Sanamyan, N.P. & K.E. Sanamyan, 2006. The genera Urticina and Cribrinopsis (Anthozoa: Actiniaria) from the North-Western Pacific. Journal of Natural History, 40(7-8): 359-393.
• Vervoort, W. & M. Faasse, 2009. Overzicht van de Nederlandse Leptolida.