Delicate wisps of flamboyant fragility gliding across the sea floor, flatworms bear a superficial resemblance to nudibranchs in colour and pattern, but nudibranchs are not as wafer thin and most species of nudibranchs have gills at the rear of their bodies and rhinophores ( head tentacles) situated behind the mantle edge.
The Firey pseudoceros Pseudoceros ferrugineus is a well known species first described by one of the great flatworm taxonomists, Hyman in 1959. It grows to around 50mm and is fairly widespread, being recorded from the Philippines to Palau and across tropical Australia.
Food consists of pink Didemnum ascidians which mostly grow beneath dead coral.
Eggs are reddish pink. ( Australian Museum)
(Photo Neville Coleman)
Delicate wisps of flamboyant fragility gliding across the sea floor, flatworms bear a superficial resemblance to nudibranchs in colour and pattern, but nudibranchs are not as wafer thin and most species of nudibranchs have gills at the rear of their bodies and rhinophores ( head tentacles) situated behind the mantle edge.
Hundreds of species of flatworms and nudibranchs inhabit shallow waters and intertidal reefs accessible to snorkellers and reefwalkers. However, to really see these magnificent, intriguing and somewhat mysterious denizens of depth, they must be observed in sea water, close up underwater, or in an aquarium.
Another fairly common and relatively easily identified species is the Grateful pseudobiceros Pseudobiceros gratus. Although it is somewhat variable in regard to the width of the black striping, recognition by visual means is not difficult.
I have many records from across the Indo - Pacific, including tropical Australia and the Great Barrier Reef. It also occurs in Japan, Ceylon, Palau, the Solomons and Papua New Guinea. ( Australian Museum)
(photo Neville Coleman)
Due to their soft bodies and living colours, flatworms have in the past been difficult to preserve in natural shape, and their colours almost impossible to retain in alcohol, or formalin, unless a great deal of care and expertise was expressed.
"New techniques of relaxation and freezing before preservation have been introduced by modern taxonomists and this has led to an upsurge in flatworm taxonomy and publication over the last 20 years."
The best, accurate method of recording shape, colour, behaviour, prey and predator relationships, and a host of other natural history observations, is by close-up photography.
(Although when I first started my self-imposed task to record the entire aquatic fauna of Australasia in 1964, I began with drawings and written observations.)
These little guys were discovered on the Sea Fan Melithaea sp. in 14 metres of water off Darwin, Northern Territory Australia in Dec. 1972.
They were perfectly adapted and I was amazed at the time as to just how their colour pattern matched the host so well.
Of course I now know that these are probably not true flatworms BUT at the time I was very keen and photographed, collected and preserved eveything I found, no matter how small.
I actually did get eventually a name for the species (Dalyelloia rhabdocoels) BUT it does not match any checklist of today.( Australian Museum)
(Photo Neville Coleman)
The History
As most Australian Marine Taxonomists of the sixties didn't place much importance on underwater photography and as so little was known, the only way to learn about underwater animals was to collect and preserve one and then take it to a museum, and hope somebody there could tell you what it was.
After 5 years collecting specimens in Sydney Harbour for the Australian Museum I realized that Marine Identification and Diver Education must become environmentally possible.
There would not be time in the future for taxonomists to key out preserved marine life every time somebody wanted to know what something was, there was just too many species and not enough taxonomists.
The only possibility was in the visual identification of living animals and this would be up to photographically recording every species.
So, in 1968 I began the long ( to me ) learning curve that was to reinvent my entire life.
LITTLE KNOWN LIFE FORMS
In the case of flatworms, there had only been a few dozen Australian species described in the scientific literature, and of these, only half a dozen had ever been published in colour in the entire history of popular Australian publishing. Around 3 species were identifiable from pictures.
In regard to the serious study of flatworms in Australia, there hadn't been any, and there were no scientific personnel able to identify (by specimen, or photograph) the wide range of species which I was encountering.
The entire procedure of identifying flatworms was too difficult, and nobody in Australia at the time was suitably inclined to take them on, as jobs and funding for flatworm taxonomy was non existant.
"In fact, it was to be another 27 years on before researchers took on the serious study and identification, together with living photography and began scientifically revising, describing and publishing the flatworm fauna of Australia, specialising in tropical forms on the Great Barrier Reef.
Dr Leslie Newman, Honorary Research Fellow of the Queensland Museum, began post-doctoral research on the taxonomy of polyclad flatworms in 1990 under the direction of Dr Lester Cannon, the senior Curator of Worms at the Queensland Museum."
In an effort to upgrade our knowledge of Australian flatworms in the early 1970's, I spoke to Mr Ian Loch (now collection manager of molluscs at the Australian Museum), himself a keen diver, naturalist and student of flatworm discoveries.
Ian advised me to contact Dr. S. Prudhoe of the British Museum of Natural History.
One of the many new flatworms I photographed and collected that were sent to Dr Prudhoe for description was the Southern cycloporus Cycloporus australis. This was discovered on a joint expedition with the Victorian Museum and the South Australian Museum to Kangaroo Island, South Australia. It was eventually described and published by Dr. Prudhoe in 1982.
Two were found in shallow water beneath a rock on their food ascidian Leach's Botrylloides Botrylloides leachii. ( South Australian Museum)
(Photo Neville Coleman)
NEW SPECIES
Over the ensuing years, I sent material - preserved flatworms; cross-referenced with their close-up colour transparencies of living colour, form, pattern and shape and Dr. Prudhoe described and published quite a number of my new species discoveries in the scientific literature.
First discovered in 12 metres of water at night at Shiprock, Port Hacking New South Wales in the late 1960's Dr. Prudhoe was kind enough to name it for me. Coleman's pseudoceros Pseudoceros colemani was eventually described and published in 1978.
The species is only found on the Brain sycozoa Sycozoa cerebriformis, generally more easily noticed at night.( Australian Museum)
(photo Neville Coleman)
However, Dr Prudhoe was in his 90's at the time and there were just so many new species, his life couldn't fit them all in. His last letter to me remarked; "Dear Dr. Coleman, please do not send me any more flatworms, I wish to die in peace."
With so many of my flatworms still housed in the Australian Museum and in the British Museum, and no hope of ever having them identified due to the time they had been preserved, a great deal of my early work donated to museums was lost in the system, due to lack of staff and expertise at the time.
Even so, the work of years wasn't entirely lost as I had all my pictures with all corresponding data, and of these over 40 species were new to science at the time I discovered and photographed them.
The Learning
As very little was known about Australian flatworms at the time (virtually no natural history at all), everything observed and studied brought forth new questions -
What was a flatworm? How did it function? Why so many bright colours?
Found at Heron Island on the Great Barrier Reef in 1976, Kent's pseudoceros Pseudoceros kentii was one of my most exciting finds. Its so strange, that even though I have completed another 10,000 dives, I have only ever found one more, at Port Stephens, New South Wales.
However, I do now why it is that some flatworms have such bright colours. They are advertising colours to warn visual predators ( such as fish) to leave them alone as they have noxious qualities.( Australian Museum)
(Photo Neville Coleman)
My learning, began at the beginning.
Flatworms belong to the Phylum Platyhelminthes of which there are two classes, Turbellaria and Acoela.
Most of the marine flatworms divers see are found in the order Polycladia.
To date there are around 15 Major families of Polyclad Flatworms, of these the main ones that divers, snorkelors and reef walkers see, belong to the families of Callioplanidae, Leptoplanidae, Planoceridae, Stylochidae, Euryleptidae, Pericelididae with most observed members belonging to the family Pseudocerotidae.
One of my original new species discoveries was the Maiden maritigrella Maritigrella virgulata at Heron Island, Great Barrier Reef in 1973. ( Family: Euryleptidae)
The specimen was lodged with the Australian Museum but was not rediscovered till 25 later when it was described by Newman & Cannon in 2000.
(Photo Neville Coleman)
Another new discovery at the time, was this Lizard maritigrella Maritigrella sp. found and photographed at Lizard Island, Great Barrier Reef in 11- 1975.
( Family: Euryleptidae) ( Australian Museum)
(Photo Neville Coleman)
In the family Pseudocerotidae there are eight genera, Bulaceros, Eurylepta, Phrikoceros, Pseudoceros, Pseudobiceros, Acanthozoon, Thysanozoon and Prosthiostomum recognised in Australasia.
(Until species are actually published in the scientific literature, species names are not available even though they are known to the scientists and museums. Scientific names are validated by scientific publication of the animal's description in a recognised scientific journal.)
Biology
Discovered at 12 metres at Heron Island, Great Barrier Reef in October 1975 the beautiful pseudoceros Pseudoceros sp. is still awaiting description.
The specimen has been housed in the Australian Museum since then but it as it was not found by the more current authorities, it has remained undescribed.
(Australian Museum) (Photo Neville Coleman)
Flatworms are for the most, wafer-thin, bilaterally symmetrical creatures which crawl across most substrates in a superficially simple, gliding motion produced by a combination of minute, beating cilia (microscopic protuberances issuing from the outer membrane of cells) on the underside of the flatworm, and muscular contraction.
Flatworms swim by undulating the edges of their body margins and by this method are able take off from the substrate, swim up into the water column and swim and drift for substantial distances. Pseudobiceros kryptos Anilao Philippines 04- 2004.
(Photo Neville Coleman)
SWIMMING METHOD
Most flatworms can also swim by undulating their body margins.
(Swimming flatworms are often called Spanish Dancers, being confused with the escape response motions produced by the nudibranch known as the Spanish Dancer, Hexabranchus sanguineus.
However, how anybody could confuse the two is beyond my comprehension, as the Spanish Dancer has an entirely different method of swimming.
I have observed tropical flatworms `taking off' from high reef and being carried along by the current for up to 20 to 30 metres before settling back down to the reef.
Flatworms have no external gills (unlike most nudibranchs), though some have marginal folds at the `head' end called pseudotentacles, which may contain groups of tiny `eyes' or light receptors. Others have true tentacles further back in the vicinity of the brain.
The pseudotentacles can be easily recognised at the left hand anterior end of this Reticulated pseudoceros Pseudoceros reticulatus. Found in 4 metres at St. Helens, Tasmania 10-1977. These flatworms were common on night dives, feeding on the stalked compound ascidians Sycozoa sp.( Australian Museum)
(Photo Neville Coleman)
The development of an anterior (front) and the combination of bilateral symmetry is closely related to the evolution of forward locomotion.
The body is made up of three layers of cells and contains a gut which opens via the mouth on the underside. The pharynx may be eversible (able to be protruded) and is sometimes used to engulf whole prey.
They can also extrude the pharynx as a multiple branched feeding mechanism, able to be extended into the siphons of colonial, and compound ascidians.
Feeding on a small compound ascidian, this Saphire pseudoceros
Pseudoceros sapphirinus
( First discovered and photographed at Heron Island in a cave at 20m 12-1975)
is able to use its multiple branched pharanx to eat a number
of ascidian zooids at the same time.( Australian Museum)
(Photo Neville Coleman)
Digested food is distributed around the body by diffusion. The early biology books stated that flatworms preyed upon small mobile invertebrates. They can also feed on invertebrates almost as large as themselves, which they swallow, digest and if there are any hard bits ( such as shells), these are expelled out through the mouth.
However, it is my experience to observe and photograph that most of those I have seen, feed directly on colonial ascidians.
Bi - lined pseudoceros Pseudoceros bimarginatus feeding on the zooids of small clumps of compound ascidians Clavelina sp. at 20 metres Heron island, Great Barrier Reef in 11- 1975. ( Australian Museum)
(Photo Neville Coleman)
Yet, I have found one species feeds on gorgonians, several on bivalves and on oysters, one feeding on tubeworms, and one living on bryozoans.
However, there is a huge amount of work still to be done in this area. Little is known regarding specific prey and predator relationships.
Flatworms have no anus (food wastes are expelled from the mouth), and no circulatory system. Respiration is achieved by the diffusion of oxygen into the body from surrounding sea water. Carbon dioxide wastes are expelled by this process in reverse.
Sex
Flatworms are hermaphrodites, having complex male and female sex organs. Mating and cross-fertilisation occur between two individuals.
Copulation itself is quite an interesting event, whereby each flatworm stabs the other anywhere in the body with its sharp everted penis, which comes out just below the mouth in the `chest' region. In the genus Pseudobiceros, the penis stylets are paired.
During courtship, the worms may circle each other, crawl all over each other and eventually face up to each other, bringing the front part of their bodies up off the bottom (rearing), penis to penis.
The body stab (intercourse) leaves quite a hole in the recipient, which may be noticed on the body for sometime after.
Rearing to stab its combatant another time, this Bi - lined pseudoceros Pseudoceros bimarginatus shows that it also has recently been impregnated and as such, will eventually lay eggs. Heron Island, Great Barrier Reef in October, 1985.
(Photo Neville Coleman)
(It is by microscopic examination of sections of the reproductive structures on which the taxonomy of flatworms is based). (It is also interesting to note that land snails and slugs use sharp, arrow-like darts which they stab into and stimulate each other during mating.)
Sometime after copulation, eggs are laid on the substrate, sometimes beneath rocks, or coral, and sometimes on, or near the species food source, though due to planktonic larvae dispersal.
The eggs are laid in spiral ribbons, somewhat similar in shape to those of some nudibranchs and other opisthobranchs (molluscs).
Egg strings of the Margined callioplana Callioplana marginata
( Family: Callioplanidae ) in an aquarium. Woolwich, Sydney, New South Wales in October 1967. (Photo Neville Coleman)
Before the prospect of underwater cameras came along I used to try and take aquarium images to record marine life. My first attempts were not so hot, but I did improve........
Although flatworms don't reproduce asexually, they are able to reconstruct two flatworms from one bitten in half, or a badly damaged one can regrow. However, sometimes the new growth does not follow the original pattern, or design, and can be more, or less.
Predators
With such fantastic colour patterns and designs, it is thought (certainly my observations bear this out) that some species at least have toxic properties (similar to many nudibranchs), and that visual predators such as fish can be repelled when trying to eat one for the first time (younger fish).
Older ones learn either not to touch them again, or learn how to `wash' out the toxic taste and eat them anyway).
(See reference "Australian Fish Behaviour" by the author).
Colour
Few mobile invertebrates (with the exception of nudibranchs and other opisthobranch molluscs) can exhibit even a fraction of the incredible diversity shown by flatworms. As studies progress, it is increasingly apparent that colour photography is becoming even more important as a scientific tool than was ever imagined by scientists decades ago.
Identified by flatworm taxonomists as the Semi pseudoceros Pseudoceros dimidiatus this (1) colour form is from Milne Bay Papua New Guinea.
(Photo Neville Coleman)
Identified by flatworm taxonomists as the Semi pseudoceros Pseudoceros dimidiatus this form (2) is from Loloata Island Papua New Guinea.
(Photo Neville Coleman)
Identified by flatworm taxonomists as the Semi pseudoceros Pseudoceros dimidiatus this colour form (3) comes from Beqa Lagoon Fiji Islands.
(Photo Neville Coleman)
( If there is so much variation as to have the same species with a positive and negative design and a zebra pattern, then perhaps it must be realized that some of the current recent descriptions of published species may not be quite as clear cut as we are led to believe, and perhaps the only answer is DNA?)
A new breed of marine scientist has arisen from the sceptical ivory armchairs of the past, entered the sea, and with an enthusiasm inspired by the pioneering underwater exploring naturalist photographers, discovered what we always new...
For recording the biological diversity of the sea and all its creatures, photography is the future!
Flatworms in Close up!
Almost any underwater digital camera which has at least 6 Megapixels can be used to record the colours, patterns, diversity and natural history of living flatworms.
With any close up study of nature's smaller creatures, two things are important: strobe lighting and depth of field. Most other things can be learnt (technique) but if your equipment is not set up to do the job, no matter how good your technique is, the results will not be adequate.
( Photo Jorina van der Westhuizen)
Flatworms in the Future?
With over 250 new species to describe just from the Great Barrier Reef and Papua New Guinea, taxonomists at the Queensland Museum have unfortunately retired, one due to retirement age and the other to ill health, and currently there is no more work going on.
It has been great to see that the scientific descriptions include colour pictures of each species. After many years of not knowing, it was such a special thing at last being able to curate some of my many flatworm pictures which are part of the Australasian Marine Photographic Index. ( World of Water Image bank)
FUTURE TAXONOMY?
Today with access to thousands of images from hundreds of locations our knowledge as to the variation in speciation has increased to the point where even the taxonomists are at times scratching their heads as to where a species begins and ends.
Certainly DNA appears to have become the new star of species determination. However, once again in reference to flatworms, all the material so far determined is from specimens preserved in formalin and for DNA purposes specimens I believe specimens need to be preserved in alcohol?
This would seem to mean that all the species must once again be found ( a piece specially preserved in alcohol, cross referenced with the flatworm preserved in formalin ( to be able to compare it to the original taxonomy of a described species) and again cross - referenced with the image?
Certainly it appears that there is a wide open field for some up and coming marine taxonomist/biologist to once again take on the field of flatworms and beginning from scratch rebuild up a profile on each and every species and republish the results. Unfortunately flatworm taxonomy is not easy and finding a job and the grant moneys might prove difficult and for this reason I doubt that it will happen anytime soon.
COLLECTING SPECIMENS
Due to my initial collecting, photography, cross - referencing and publishing efforts and those who have followed my lead, we can now identify over 7000 species of Marine Life by visual means and there is no longer any reason to collect specimens to get identifications. So, all my reasons for doing all the work in the first place have been realised at last.
Conservation by Camera has arrived!
It is important to realise that we have been so succesful at having Marine Parks declared that much of our accessable coastal areas are reserves and that indescriminate
collecting without a permit is unlawful.
Should specimens be required by Museums, Fisheries, or National Park services, permits can be obtained.
Originally found at Dunsborough, Western Australia in 06-1971 and described by Dr. Prudhoe in 1977, this species was known as Pseudobiceros fuscopunctatus. Since then it has been allocated to another genus and is now known as the Orange - spotted maritigrella Maritigrella sp. and the name of fuscopunctatus has been alligned with another of my discoveries. ( see below)( Australian Museum)
(Photo Neville Coleman)
Found at 10 metres at Heron Island in 11-1976 this species was photographed and collected and housed at the Australian Museum. It was to be another 25 years before it was found again and published by (Newman & Cannon, 2000) as the Dusky maritigrella Maritigrella fuscopunctatus. There is some resemblance to the species above but certainly not enough to confuse the two.
So, I now have another species still out there, from one I thought was determined long ago.
I guess flatworm taxonomy is a bitch!( Australian Museum)
(Photo Neville Coleman)
I was a bit disappointed by the fact there was no mention of any my pioneering collecting work on flatworms and no reference to any of my registered specimens housed at the Australian Museum, or any reference to the many specimens donated to the Queensland Museum in any of the new scientific papers describing a large number of my original discoveries.
I was informed in two different messages from the Queensland Museum flatworm taxonomists that (1) my material was not preserved to their standard of taxonomic requirements and (2) ( years later) that all my AMPI cross- referencing numbers had somehow got mixed up?
However, I can now publish my own credits and my contribution of discovering over 450 species new to science and I will still include those flatworms I originally discovered and photographed 20 years previous to any collection dates of those species published in scientific papers.
With the Marine Life Inventory of Dive Sites coming more into reality each year, photographic fauna surveys, teach tours, underwater naturalist and photography courses and tours taking place across Australasia on a regular basis, flatworms are high on the list as subjects of our photographic fauna surveys and I for one will continue to keep my flatworms in focus!
Acknowledgements
I would like to take this opportunity to thank Mr. Ian Loch, Dr. Prudhoe,( posthumously) Dr. L. Newman & Dr. L. Cannon ( for current identifications) and the Boards of the Australian and Queensland Museums for assistance and for housing my donated specimens over the many years of association. I have over 4000 specimens located at Australian Museums and with over 6000 species published in colour in my books, I would hope that in my own way ( regardless of the pitfalls) I have contributed to advancing the overall knowledge of Asia/Indo - Pacific Marine Life.