Australonuphis teres occupy the sandy intertidal zones along Australia’s eastern coastline, ranging from Victoria to Maroochydore. They area common source of food for coastal marine life, particularly sand whiting, and are often used by recreational fisherman as a source of bait. They are a scavenger species, feeding on decaying carcasses of, fish, birds and any other animals that may wash ashore. The Australonuphis genus are characterised by their anterior 5-8 pairs of modified parapodia, anterior rounded prostomium and short styles (Paxton,1986). Morphologically Australonuphis teres is very similar to Australonuphis parateres, who also inhabit the same coastal regions. The two can be distinguished from one another by the presence or absence of brown pigment on the anterior portion of their setigers. The degree to which these two species co-exist,is not well documented and as such a small study was conducted to measure the relative abundance of the two species on kawana beach in the sunshine coast. The findings of the study suggested that whilst the species have been found in the same geographical ranges there may be evidence of isolation between populations at a local level, although further study is needed.  

A.teres, is one of two species of beach worm belonging to the genus Australonuphis. It is bilaterally symmetrical, and cylindrical in shape. The species ranges in sizes from 3 cm as a juvenile up to 1 meter in length and 2.5 cm in width as an adult (Paxton, 1979).  Being from the same genus, A teres shares most of its morphology with a sister species A.Parateres, and whilst in sediment the two are very difficult to tell apart. A. teres can be distinguished from A. Parateres, by the presences of brown banding on the dorsal side of each setiger, as well as brown pigmentation on the anterior antennae (Paxton, 1986)(Figures 1,2). A. Parateres also excretes substantial amounts of slime, not observed in A. teres, and grows to significantly larger sizes; 300cm long, 1.5cm wide (Wild fisheries research program NSW, 2008).

Australonuphis teres are not restricted to a single burrow and have the capacity to move around and as such their habitat preference has not been largely studied, but are typically observed inhabiting sandy intertidal zones along Australia’s eastern coastline, ranging from Victoria to Maroochydore. They prefer low gradient slopes, with substantial amounts of intertidal movement. (Status of NSW fisheries resource, 2009). They are detritivores and as such eat decaying material, effectively ‘cleaning’ the benthos. Additionally they are also a common source of food for many coastal species (Status of NSW fisheries resource, 2009), their ecological importance however as a lower trophic level species is not well documented.     

Reproduction 

Feeding and locomotion

Australonuphis teres are scavengers feeding on a variety of decaying organic material, ranging from; dead fish, birds, Molluscs, other invertebrates and seaweed. The worms are also a common source of food for most coastal marine life, such as fish, birds and crabs (Status of NSW fisheries resource, 2009). Typically, A. teres use’s longitudinal muscles to move vertically through the sediment. When feeding the anterior end of their body, typically 4-8 setigers will protrude out of the sediment into the water Colum of an outgoing wave to catch passing organic material. If caught, the individual will ‘arch up’ and extrude its pharynx to grip the material in its jaw, and then pull itself down in one smooth motion pulling the material of the carcass and down into its burrow.

Australonuphis teres belong to the class Polychaeta and the family Onuphidae and as such is triploblastic, bilaterally symmetrical and coelomate. The anterior section of their bodies is cylindrical to accommodate for an eversible pharynx, whilst the posterior end is slightly dorsally flattened (Paxton, 1986). The eversible pharynx comes out of a mouth cavity, located on the ventral side of the anterior region of the animal (Figure  6).  A. teres has a complex jaw within its eversible pharynx, a characteristic shared by members of the onuphid family. The jaw contains a pair of mandibles that grow continuously throughout its life span, forming identifiable growth rings (Paxton, 1986). As well as rows of maxilla, which also continue to grow throughout its life span. The maxilla do not grow in rings as the mandibles do, rather the growth of the maxillae is thought to occur from the inner epidermal layer of the cavity they sit in, with new teeth being derived from the division of the most distal teeth (Paxton, 1986). 

A.Teres have well developed branchiae that begin on setiger 6-7 (Paxton,1979). It was suggested by (Fauchald 1982) and (Paxton 1986) that the well-developed branchiae may be because they inhabitant non-Permanent tubes and require more specialized branchiae to compensate for the poor aeration of their tubes,comparative to that of permanent tube dwellers. The size of the individuals was also suggested to be a factor (Paxton 1986). A. teres have highly developed longitudinal musculature, utilised in burrowing and attaching to the inner burrow walls, making them difficult to remove. They also secret a mucus lining within their temporary burrows to strengthen the walls (Queensland marine identification guide, 2017).

Their anterior most segment is called a Prostomium and consists of five dorsal antennae and a pair of labial palps, located ventrally (Paxton, 1980).  The antennae consist of proximal ceratophores and distal styles, these styles are covered in sensory/secretory structures referred to as 'Sinnesknospen' (Paxton, 1986),This enables A. Teres to gather information from the water column, however there full range of sensory capability’s is unknown.

On Each setiger A . teres has a pair of parapodia, the 6 most anterior stigers however are unique in that the parapodia have been modified into pseudo compound hooks (Paxton 1986)(Figure 3, 4) ,likely to grip onto passing organic matter and keep it from being pulled away by the waves and tide as well as assist in burrowing. The parapodia also change as you travel further towards the posterior end of the animal. There is a long transition zone of glandular pads with reduced cirri until setiger 15-25, the cirri later fuse with the ventral pad by setiger 40-70 (Paxton,1986) (Figure 7). 

The light sensory spot present in most Laval forms of onuphid (Paxton 1986), was believed to be observed in the A. teres specimens examined (Figure 5) suggesting the individuals may not have been fully developed. To test if these were eye spots, during the night time a bright light was shone on the individuals and they became visually agitated, violently swivelling, suggesting they had some limited ability to detect the light.  The presence of these spots could be an interesting point of further study. Perhaps, they help in orientating up from down during initial settlement phases, finding and making new burrows in sediment or are maintained for a short duration post Laval phase for some other means. None of the individuals collected were larger than 40cm, which is the general size of sexual maturity (Queensland marine identification guide,2017) and thus they may have just been undergoing the final stages of transition from juvenile to adult form, as adults are typically blind (Paxton,1979).

A. teres, and A. Parateres are two species of the Australonuphis genus found in Australia, they along with a third species Hisutonuphis mariahirsuta, all are a part of the Onuphidae family and make up the group of animals commonly referred to as beachworms (Status of NSWfisheries resource, 2009) (paxton1986). All three species have been observed up and down the eastern coast of Australia, from NSW to Yeppoon. Whist they share this habitat with one another, the relative abundance of each species is not well known, particularly due to the difficulty in discerning A .teres and A. Parateres apart in sediment.  With limited time and resources a full scale study of the Australian coastline was out of the question, however a local study on the sunshine coasts Kawana beach was conducted with the aim of measuring the relative abundance of A. teres and A. paratres.

Method

Four 1x1 meter transects were placed 25 meters from the dunes along the foreshore of beach held down from the waves by metal pegs. Each transect was placed 15 meters apart from the other, spanning a 60m stretch of the beach. Each transect was ‘baited’ with a bag of decaying squid for 2 minutes. After this point the total amount of worms observed in the transect was recorded, and then five from each were picked at random to be caught (Figure 8) through the tossing of a coin and were later examined and categorised into species with the assistance of a magnifying glass. Due to limited man power the transects were laid, baited and measured 1 at a time.  This was conducted during the low tide of Monday the 28^th of May 2018,between 10am-2pm.

Results

The average number of worms observed per transect was 9 (n=4, rounded down),with transects 1, 2, 3 and 4 having 11 , 11, 3 and 13 worms observed respectively. A total of 20 individuals were collected, 5 from each transect except for transect 3, which had the two worms nearest the transect collected in addition to the three inside. Of the 20 worms collected, all 20 were observed to be A. Teres. Showing A. teres had a higher relative abundance than A. Parateres (P<0.05) which were not observed.N.B* no Hisutonuphis mariahirsuta were observed.  

Discussion

The total absence of A. Parateres was unexpected and may have been due to some level of competition between the species, causing localized separation. It may also have been due to their natural tendency to occur in patchy distributions (Queensland marine identification guide, 2017). It is also possible that a mechanism of larval settlement may promote settling near adults of the same species, and result in a similar scenario of localised separation. Due to QLD bagging limits, the total No. of specimens collected may also have been a factor, and a simple increase in sample size may yield a differing result, as well as increasing the sample range, taking samples over numerous days and differing tides. Miss identification may have been a factor. It is also possible that the pushing of tent pegs into sediment skewed results in the form of a disturbance. Due to the limited nature of the study, results and conclusions should be observed with a healthy dose of scepticism. They may serve as a foundation for future studies however regarding the ecology of the Australonuphis species . An interesting point of note, is that the results may also be an indicator that some level of population isolation does occur between the species and may have aided historically in the inhibition of gene flow between populations, however being broadcast spawners this would remain to be seen.

Evolutionary history & classification 

Kingdom: Animalia
Phylum:Annelida            
Class:Polychaeta
Order:Eunicida 
Family:Onuphidae
Genus: Australonuphis
Species: Australonuphisteres

Australonuphis teres are classified as polychaetas because of their segmented bodies and parapodia, a feature shared by all polychaetas. They are further classified in the order Eunicida due to a ventral eversible pharynx that houses a complex jaw apparatus, with ventral mandibles and dorsal maxillae, a trait shared by all members of the Eunicida (Paxton, 1986).  They are further categorized as Onuphidae, a sister group to the Eunicida. In Onuphidae notosetae are reduced to internal setae in the dorsal cirrus, or are completely absent, as well as the presence of well develop ceratophores and frontal palps (Paxton,1986). In some species the palps are reduced and/or absent (Paxton, 1986).

Australonuphis are characterized by their anterior 5-8 pairs of modified parapodia, anteriorly rounded prostomium and short styles (Paxton,1986). The Presence of a maximum of 7 Branchiae from setiger 6 with thick stem and pectinate filaments, strongly sclerotized mandibles and tube structure with a layer of mucus inside (Paxton, 1986).  A.teres and A.parateres are unique in their genus as they are the only two that express six anterior segments with pseudo compound hooks, and can be distinguished from one another by the presence or absence of brown transverse banding on the dosal side of the setigers (Paxton,1986) (Figure  9) .

The resent evolutionary history of A. teres is not well studied, and remains a point of scientific interest as to what mechanisms may have driven the speciation of A.teres and A.parateres, given that they share the same geographical distribution.

Commercial value and threats 

Due to being the natural prey of many coastal fish species,they are often used by anglers as a bait source to catch, Whiting, Dart, Bream and Flathead (Status of NSW fisheries resource, 2009).  In order to catch A . teres the nature of their feeding is exploited by fishermen. In practice, a bag of decaying fish is swashed in the waves enticing the animals to stick their heads from the sand, a fisherman will then place a small piece of fish in front of the animal to grip. Whilst the animal is gripping the material the fisherman slides his fingers into the sediment parallel with each side of the worm ensuring there is a layer of sand between his/her fingers and the animal so as not to ‘spook’ the worm. Once the worm begins to arch up and extrude its pharynx to better grip the prey the fishermen pinches the sides of the animal and pulls it from the sediment. Due to the strength of their muscles, and in the case of A. teres, the absence of slim this can sometimes be very difficult and result in a tug of war that can cause the worm to  snap in half under the strain.  

A. teres and other beach worms are collected by commercial and recreational fishermen, however the labour intensive nature of their capture keeps the industry relatively small. The annually harvests have been deemed non-impactful in relation to the amount of available bio mass (Status of NSW fisheries resource, 2009). Although the fishery has the potential to be much larger than it currently is, without a means of increasing the efficiency of extraction it is not commercially viable to expand.

There has been speculations about increasing urbanization and activity on beaches affecting both A. teres and A. parateres populations, although no study has been able to demonstrate such an effect to any degree of statistical significance.

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