Greg Rouse’s Marine Worm (& Feather Star) Research

Eight Mile Creek Report

The MLSSA Newsletter

The MLSSA Newsletter is your newsletter and it only exists because of contributions from MLSSA members.

My main contributor is Steve Reynolds and he is to be thanked for his diligence in providing so many articles.

However, it is important to have a variety of contributors in order to give balance and range in the topics.

So can I ask all members and friends of MLSSA to put pen to paper, finger to keyboard and supply me with some material for the 2006 year. Illustrated articles are preferred but I can usually source suitable pictures if necessary.

Greg Rouse’s Marine Worm (& Feather Star) Research

by Steve Reynolds

(Part 2)

Greg wrote that the discovery of Myzostoma australe “represents the first description of a myzostome from southern Australian waters” and that it is “distinct from that noted by Grygier (1990) in South Australia, (his species No.37)”.

Now it seems to me that Grygier’s species No.37 is the same one reported in our February 2004 Newsletter (No.307). The article “New Bluff Resident Discovered” in that newsletter explained that Myzostoma seymourcollegiorum “grows to 1cm in diameter and is symbiotic*, living only on a featherstar (crinoid). Myzostoma live as free roaming symbionts* on their host featherstars and are often strikingly camouflaged”.

(* Greg later told me that he considered that “symbiosis is a very broad term that means ‘living together’. Commensalism is where one species benefits and the other is unaffected; Mutualism is where they both benefit. Parasitism is where the host is damaged by the other. With Myzostoma we are often not sure if is commensalism or parasitism so I used the general term symbiotic.”)

The article explained that “The featherstars are filter feeders that catch plankton from the water. The worms use their sucking mouths to dip into the food grooves (like troughs) of the crinoid and take some of the food before it gets to the crinoid’s mouth”.

It went on to explain that “The host crinoid, Cenolia trichoptera, reaching up to 30cm in diameter, is found around the southern coast of Australia. It is common in only 2m of water along the rocky area leading out to the Bluff. This will be the type locality of the new species of Myzostoma. Cenolia trichoptera, and hence its fellow-travelling little worm, can easily be found . .”. More about Cenolia trichoptera later.

A paper, written by Greg Rouse and Mark Grygier, describing Myzostoma seymourcollegiorum was published mid-2005. It is titled “Myzostoma seymourcollegiorum n.sp. (Myzostomida) from southern Australia, with a description of its larval development”. A copy of this paper has now been put into our library.

The naming rights for the species went to Mrs Bardie Simpson who wanted to name the worm after her old school, Seymour College at Glen Osmond, after becoming the successful bidder of an auction held for the rights. Mrs Simpson addressed a school assembly on 22^nd March 2004 to tell the students about naming the worm after their college. The next day’s Advertiser reported the adoption of the name.

I asked Greg for the full classification details for Myzostoma. He told me that “Myzostoma is inside Myzostomatidae, Myzostomida. Where the group goes after that is still the subject of research. I think they belong inside Phyllodocida, Annelida but others suggest that they may be closer to Platyhelminthes. The jury is still out”.

The species of feather stars that Lauren Johnston was studying for her honours degree in science in 2002 were Aporometra. These are a variety only found in southern Australia. A colony of them were found on a reef at Witton Bluff, near Port Noarlunga. Lauren said that they are very hard to see and well-camouflaged amongst the seaweed.

The Advertiser of 22^nd March 2002 said that “Aporometra is the smallest known variety of feather star, easily fitting on a human finger tip. It is also unusual because it gives birth and cares for its young, unlike other feather stars which reproduce by spawning their sperm and eggs into the sea.”

The article in the paper, written by Science Reporter Brad Haran, went on to say that “About 600 kinds of feather star are found internationally, including 70 on the Great Barrier Reef, but there are only six species in SA. The unusual Aporometra was named by one of the world’s leading experts on crinoids, the late Dr Austin Clark, but he did not describe their behaviour or unusual breeding.

“The breeding is thought to work by males releasing sperm into the water and females catching it in their spectacular arms, known as pinnules. Eggs are fertilized and young creatures develop, then new-borns cling to the arms of their parents until they are old enough to drift free.

“The only other crinoids known to breed this way are much larger and found in the waters off Antarctica. Ms. Johnston’s study . . will involve a detailed analysis of the creatures’ DNA and anatomy, using various technologies including an electron microscope.”

Marine Inverts. 1 describes Aporometra species as “Cirri relatively very large, about as long as the arms and not laterally compressed; arms up to 25mm long”. Only one species from SA is described. It is Aporometra wilsoni which is said to be “small . . with arms rarely longer than 25mm and brown, orange or red in colour depending on the colour of the host alga. They often occur in densities exceeding 100 per individual plant. (They) are . . viviparous i.e. the fertilized eggs undergo development on the pinnules. The recorded depth . . is to 30m”. The glossary describes ‘pinnules’ as “slender jointed appendage on arms of crinoids”.

“Sea Stars of Australasia and their relatives” by Neville Coleman says that “A number of other sea creatures have formed close relationships with feather stars (and other echinoderms?), including cling-fish, gobies, snapping shrimps, pontonine shrimps, squat lobsters, worms, brittle stars and crabs. Small parasitic molluscs also live on them”.

Neville Coleman’s “Underwater” magazine (later “Underwater Geographic”), issues 7 & 8 discussed echinoderms including commensalisms and parasitism. Issue 8 said that ’ectoparasites’ are (mollusc) “parasites which retain their shell and can be seen on the surface or hidden in living galls”. The article features a photo of the parasitic univalve Stilifer species burrowed deep into a sea star’s arm, causing a living gall (blister-like swelling or outgrowth).

In 1971 Neville Coleman discovered and photographed an undescribed species of commensal worm on the Rhinoceros (or Horned) sea star Protoreaster nodulosus (or nodosus) - Family Oreasteridae. That same year he discovered that the Dancing shrimp, Hymenocera picta was a voracious predator on small sea stars. I seem to be, however, getting away from the topics of worms and feather stars.

On page 279 of “Reader’s Digest Book of the Great Barrier Reef” there is a photo of a (Precious?) clingfish, Lepadichthys lineatus (or Lepadichthys caritas), clinging to the arms of a Comanthus feather star. The caption for the photo says that this “clingfish uses its sucking disk to cling to the arms of a Comanthus feather star and is superbly camouflaged by its longitudinal stripes and background colour patterns which blend perfectly with that of its host*. These fish are predators on other feather star symbionts – they eat worms and shrimps and occasionally some of the host’s tissues”.

(* Sounds like a case of ‘allosematic’ colouring – the use of the colours of another animal by hiding in it or blending with it.)

A (Precious?) clingfish, Lepadichthys caritas can be seen on a feather star on page 55 of the book “Australian Fish behaviour” by Neville Coleman. The caption for the photo (a) says that the clingfish is “Only found on and around feather stars . . (and it) is not as rare as once thought and occurs over a wide area where its crinoid hosts are abundant”.

Another little clingfish that may be found on other echinoderms (& more) can be seen on page 54 of Neville’s book. The caption for the photo of the Long-nosed clingfish, Diademichthys lineatus (c) says that it “inhabits sea urchins, Crown of Thorns sea stars (and) staghorn corals”.

Now for some more details about Cenolia trichoptera. Greg tells me that the description of Cenolia trichoptera in Marine Inverts. 1 is actually another species, Cenolia tasmaniae. A photo of Cenolia trichoptera can be seen on page 358 of “Australian Seashores” by Isobel Bennett. Comanthus species such as Comanthus bennetti, C. japonicus and Comanthina nobilis occur on the Great Barrier Reef and photos of these species can be seen in “Reader’s Digest Book of the Great Barrier Reef”, Reader’s Digest Services P/L, Sydney, 1984.

Now for more details about Ptilometra macronema. “Sea Stars of Australasia and their relatives” by Neville Coleman describes Ptilometra macronema as follows: - “Family: Ptilometridae, Common Name: Long-cirried feather star, Distribution: Temperate seas, Depth: 25 – 120m, Habitat: Rocky reefs, Food: Plankton, Size: 150mm and Notes: The long-cirried feather star is found attached to algae, rocky reefs, bryozoans and gorgonians. The species is extremely prevalent in the deeper waters throughout its distribution, and its colour pattern seems to be constant. The animal is firm to the touch with spiny arms and extremely long cirri which it uses to cling to objects on the bottom. The first specimen of this species was studied in Europe over 130 years ago, the type locality being given as King George Sound, south-western Australia. It can be distinguished from its eastern counterpart, the southern feather star (Ptilometra australis), by the number of arms on adult specimens (25 to 31), and in most cases P. australis is dark purple. Both species are generally fully expanded night and day.” Marine Inverts. 1 describes Ptilometra macronema as having “Pinnules spike-like, stiff, upstanding and triangular in cross-section; arms to 70-80mm long” and “An attractive species with brittle arms delicately coloured orange, red or purple, common in deeper water (20-50m) attached to sponges, bryozoa or rock. The species ranges from Shark Bay, WA to Port Phillip Bay, Vic.”. There is a photo of Ptilometra macronema by the late Kevin Branden in the book (Plate 29.1). Another photo can be found in Neville Coleman’s book (on page12).

As discussed earlier, polychaetes used to be divided into the two Orders Errantia and Sedentaria according to whether they are ‘free-wandering’ (Errantia) or they are modified for a permanent life in tubes or sand-burrows (Sedentaria). When I asked Greg about this later, he directed me to :-

http://tolweb.org/tree?group=Annelida&contgroup=Bilateria . I have kept a file copy of the web page which included the following comments about ‘Errantia’ and ‘Sedentaria’'.

“Until relatively recently the most commonly used system to divide polychaetes was as ‘Errantia’ and ‘Sedentaria’. This was essentially a system of convenience with no real intention of depicting evolutionary relationships. This classification was supplanted in the 1960s and 1970s by ones which split polychaetes into as many as 22 orders with no explicit linkage between them (Fauchald and Rouse, 1997). A recent cladistic analysis of Annelida and other groups has resulted in a new classification of polychaetes (Rouse and Fauchald, 1997). This used an evolutionary tree of worms as the basis for the naming of groups. There are two major branches containing all polychaetes- Scolecida and Palpata. Scolecida is a small group of less than 1000 named species, and these worms are all burrowers of one form or another, with bodies reminiscent of earthworms. Palpata comprises the vast majority of polychaetes and is divided into two branches; Aciculata and Canalipalpata. Aciculata contains about half of the polychaete species and largely encompasses the old taxonomic group Errantia. Representatives of this lineage are characterized by having internal supporting chaetae, or aciculae, in the parapodia. It includes major groups such as Phyllodocida and Eunicida, which tend to be mobile forms with well-developed eyes and parapodia for rapid locomotion. Canalipalpata, a group with more than 5000 named species, is distinguished by having long grooved palp structures that are used for feeding. Canalipalpata is then subdivided into Sabellida, Spionida and Terebellida. Most of these groups’ members live in tubes and use their palps* to feed in various ways.”

(*A glossary in Marine Inverts. 1 describes ‘palps’ as being “paired projections arising from the sides of the head” and these are illustrated in Fig.6.6B (bp) on page 244 of that book.)

I asked Greg to explain the many names used on the web page. I asked him “Which names are Class, Order, Family, etc.. - Scolecida and Palpata, Aciculata and Canalipalpata, Phyllodocida and Eunicida, Sabellida, Spionida and Terebellida?” and “Are all those that end in ‘ida’ Orders, those that end in ‘ata’ Classes and those that end in ‘idea’ Families?” He told me “For a variety of reasons I tend not to use taxonomic ranks such as Class, Order or Family. The ending ‘idae’ is only used for family but the other names were developed as a rankless classification. People have applied them with ranks in various ways and I’ve done this for you on your Excel spreadsheet. FYI, I’ve attached a very technical article on why I am for a new system”.

The attachment was a paper titled (in French) “Ceci n’est pas une pipe:names, clades and phylogenetic nomenclature” which had been written by Fredrik Pleijel and Greg Rouse. It was an introduction to the literature and to issues relating to phylogentic nomenclature and the PhyloCode, together with a critique of the current Linnaean system of nomenclature. This paper has been added to our library.

I also asked Greg if he could suggest the necessary changes to the worm section of our Photo Index Excel spreadsheet file. He made several changes to the file himself and I was then able to copy those details straight into our complete spreadsheet file. Work on the spreadsheet is still continuing with Greg’s assistance.

I see from many of the above mentioned papers that Greg Rouse has also written many more papers, including “A cladistic analysis of Siboglinidae Caulerry, 1914 (Polychaeta, Annelida): formerly the phyla Pogonophora and Vestimentifera”, Zool. J. Linn. Soc. 132, 55-80”, 2001. He also co-wrote (with K Fauchald) “The articulation of annelids”, Zool. Scr. 24, 269-301, 1995.

Many of Greg’s papers include photomicrography. “Encounter 2002 Expedition to the Isles of St Francis, South Australia: Myzostoma australe (Myzostomida), A new crinoid associated worm from South Australia” features photos of Myzostoma australe and “Myzostoma seymourcollegiorum n.sp. (Myzostomida) from southern Australia, with a description of its larval development” features photos of Myzostoma seymourcollegiorum.

The book “Marine Flatworms – The World of Polyclads” by Leslie Newman and Lester Cannon, a recent acquisition for our library (mlssa No.1055), has a good chapter about worms in general, including marine worms.

BIBLIOGRAPHY:

“Greg Rouse – worms and featherstars” file including newspaper cuttings – mlssa 2215.

“Encounter 2002 Expedition to the Isles of St Francis, South Australia: Myzostoma australe (Myzostomida), A new crinoid associated worm from South Australia” in the “Transactions of the Royal Society of South Australia (2003), 127(2), 265-268, 28 November, 2003” – mlssa No.2216.

“Myzostoma seymourcollegiorum n.sp. (Myzostomida) from southern Australia, with a description of its larval development” by Greg Rouse and Mark Grygier, Zootaxa 1010:53-64 (2005), ISSN 1175-5326 (print edition) ISSN 1175-5334 (online edition) – mlssa No.2217.

“Annelida” by Greg Rouse, Fredrik Pleijel and Damhnait McHugh

- mlssa No.2218.

“Osedax: Bone-eating Marine Worms with Dwarf Males” by GW Rouse, SK Goffredi & RC Vrijenhoek – mlssa No.2219.

“Worms discovered living on whale bones” (source unknown) – mlssa No.2220.

“Ceci n’est pas une pipe: names, clades and phylogenetic nomenclature” by Fredrik Pleijel and Greg Rouse, J.Zool. Syst. Evol. Research 41 (2003) 162-174, ISSN 0947-5745 – mlssa No.2221.