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Arm regeneration in the eleven-armed sea-star Coscinasterias calamaria (Gray, 1840)
Invertebrata 5, Spring/Summer 1995/96

The Eleven-Armed Seastar Coscinasterias calamaria (Asteroidea: Asteriidae) is a moderately large seastar, common in the lower intertidal region and to depths of 80 m. It occurs around the southern coast of Australia. Generally it is mottled blue, grey and brown in colour, has large spines on the arms and can attain a greatest radius R of 250 mm (Fig. 1).

As the English name suggests, these animals should normally have 11 arms. However, it is very common to find individuals with arms missing or regenerating and the total number of arms has been reported to range from 7-14 (Zeidler & Shepherd 1982). The main reason for this is that C. calamaria can reproduce by self-division (a form of asexual reproduction). The autotomised arms form into a separate seastar. It has been suggested that in Victoria most of the larger individuals of this species have the full complement of arms (P.M. O'Loughlin, pers. comm.). This implies that only the smaller animals undergo regular self-division. With this in mind, the incidence of arm regeneration in specimens of C. calamaria in relation to the size of the animal was briefly investigated.

During field trips to the rocky shores of northern Tasmania in the winter months of 1994, 53 specimens of C. calamaria were found in the intertidal region. When an animal was located, R was measured (see Fig. 1) and the number of regenerating arms, if any, was counted, as well as the total number of arms. The animals were assigned to a size class depending upon R. The number of regenerating arms per animal was then regressed against its size class (Fig. 2).

The greatest number of arms being regenerated at any one time was seven (Fig. 2), and the total number of arms varied from six to 14. In some specimens, the regenerating arms were in two or three groups of different lengths indicating that those animals had undergone self-division several times within a short time period. The resulting relationship between the size of the animal and the number of arms regenerating (Fig. 2) shows that the smaller and larger animals of this species tend to have the full complement of arms. Therefore self-division is more common in the medium-sized animals (those with an Ri of 41-60 mm).

It must be stressed that this was a very small study and was confined to two to three sites along northern Tasmania. To gain a better understanding of the relationship between reproduction (both sexual and asexual) and size in C. calamaria it would be instructive to know whether the medium-sized animals also undergo sexual reproduction to the same extent as the larger animals or whether self-division requires most of their energy. Dartnall (1969) reports that juveniles of this species have an R <20 mm, that is, juveniles are those animals in size class 1 (Fig. 2). As juveniles do not reproduce sexually, it is likely that most of their energy goes into growing rather than into any form of reproduction. This hypothesis, however, would need to be investigated. It would be worthwhile to conduct a larger study to test whether the observed relationship holds true for all C. calamaria in Tasmania. This would be a good project for the newly formed Marine Field Naturalists to complete.

Jane Griffith
Research Officer, Zoology, QVMAG

References:

Dartnall, A.J. 1969. New Zealand seastars in Tasmania. Papers and Proceedings of the Royal Society of Tasmania 103: 53-55.

Zeidler, W. & Shepherd, S.A. 1982. Sea-stars (Class Asteroidea). In Shepherd, S.A. & Thomas, I.M. (eds), Marine Invertebrates of Southern Australia. Part 1.


Fig. 1. A specimen of Coscinasterias calamaria (Gray, 1840) with regenerating arms. R is the 'greatest radius,' measured from the centre of the disc to the tip of the longest arm. Illustration by Judy Rainbird, QVMAG.

Fig. 2. The relationship between the number of regenerating arms for an animal of C. calamaria and its size. X-axis = size class, y-axis = no. of regenerating arms. Size class 1 has R = 0-20 mm; 2, = 21-30 mm; 3, = 31-40 mm; 4, = 41-50 mm; 5, = 51-60 mm; 6, = 61-70 mm; 7, = 71-80 mm; 8, = 81-90 mm; 9, >90 mm. The fitted curve (y = 0.43 + 1.08 x - 0.12 x-squared) is significantly different (p<0.01) from a horizontal straight line. (A horizontal line would indicate that there is no relationship between the number of regenerating arms and the size of the animal.)

Death by sponge
Invertebrata 5, Spring/Summer 1995/96

During July 1995, a 3-4 month-old puppy ate a small piece of sponge washed up at Low Head, northern Tasmania, and promptly died. Following a post-mortem the sponge was identified by Lisa Hobbs (Department of Chemistry, University of Melbourne) as belonging to the genus Cribrochalina (Order Haplosclerida, Family Niphatidae).

Although it is a common sponge, little is known of its chemistry. Many sponges have toxic or noxious chemicals and the type of chemical varies not only between species but also within species collected from different parts of the ocean (R. Capon, pers. comm.). According to James Watson (Department of Primary Industries and Fisheries, Launceston), the puppy died too quickly to determine what part of the animal was affected specifically by the sponge toxin. And so, if you're at the beach with a small child or dog, be aware that some sponges washed ashore may still contain enough toxins to cause sickness if eaten.

Jane Griffith
Research Officer, Zoology, QVMAG

Treatment of redback spider bite
Invertebrata 5, Spring/Summer 1995/96

Several months ago our department received an inquiry regarding the treatment of bites from the Redback Spider, Latrodectus hasselti. Our caller had spoken to a particular hospital and was told by a medically qualified person in the emergency department to apply the pressure-immobilisation technique used for snake bites. On further investigation, a call to a particular centre one would call in this situation revealed that a constriction bandage should be used, but not a tourniquet!?? This was very worrying.

A recent article on envenomation points out that approximately 2000 people in Australia are definitely bitten by the Redback Spider each year. In 80% of cases, mild local symptoms are treated with analgesics. Severe symptoms may be experienced by about one in five patients and if untreated may persist for up to several months.

The bite should be treated by the application of an ice pack or compress for local pain and medical treatment should be sought as soon as possible. Redback Spider envenomation occurs relatively slowly so unless severe symptoms (e.g. vomiting, headache, nausea, hypertension and tremor) are present, there is no need for urgency.

Louise McGowan
Research Officer, Zoology, QVMAG

A proliferation of Rosy Screw Shells
Invertebrata 5, Spring/Summer 1995/96

The Rosy Screw Shell, Maricolpus roseus, belongs to the family Turritellidae which contains about 50 species. Originally native to New Zealand, it was accidentally introduced into Tasmania in the Hobart area, probably via ballast water, several years ago. This alien invertebrate has since spread south as far as Recherche Bay and north as far as Cape Portland.

Rosy Screw Shells are herbivorous molluscs which live in the sand and mud below the tide level. They are prolific breeders and compete strongly with indigenous species, almost to the point of exclusion.

The aftermath of recent East Coast storms (9-10 November 1995) saw M. roseus washed up at Falmouth in their thousands. In a typical one-metre-square quadrat I counted 563 individual shells on the sand surface alone. They were densely packed and outnumbered other molluscs species by 50 to 1.

As an aside, the same storms also brought in two Balmain Bugs, Ibacus peroni, the first such specimens I have seen on Steels Beach in over 35 years of beachcombing. On the same day, 12 November, I also identified a single Dominican Gull, Larus dominicus, again the first of this species recorded at Falmouth, although they are common further south.

Tim McManus
Falmouth, Tasmania

Evening strolls in the forest
Invertebrata 5, Spring/Summer 1995/96

Many so-called 'cryptic' invertebrates are hidden only by day. At night they emerge from their shelters to browse, hunt, mate or change address, and can be easily observed or collected by torchlight.

In 1990 and 1991 (references below) I hand-collected a range of litter invertebrates on 0.05 ha circular plots laid out in the forest. About one-third of all species collected were represented in the nightcatch. A few species were only collected at night. When I calculated the per-hour catches by night and day for different invertebrate groups, I found, perhaps not surprisingly, that snails, spiders and flatworms were collected faster after dark. The day and night rates were more or less the same for millipedes and velvet worms.

My biggest night-time surprise was finding earthworms climbing manfern trunks. In a New Zealand study (Moeed & Meads 1983), earthworms were among the invertebrates taken in traps designed to capture upwardly mobile animals (up-traps, as opposed to down-traps). The authors suggested that the earthworms were fleeing rain-soaked ground and heading for perched litter in limb crotches.

For serious evening strolls I recommend a serious torch - a powerful headlamp, not just a handheld firefly that gobbles up drycell batteries. For the 1991 study I fixed a 6 volt, 21 watt lamp unit from an auto parts shop to the plastic 'inner cap' from a discarded hard-hat. Heavy gauge wire connected the lamp via a switch to a 6 volt lead-acid motorcycle battery carried in a belt pouch. The canvas pouch was lined with a thick plastic insert (a suitably sized lubricant container with its top cut off, used to catch any acid spills from the battery) and all connections, slits and cracks were waterproofed with plastic tape. This homemade apparatus cost about $40 in 1991 and gave me 4-6 hours of very bright, wide-angle illumination before a battery recharge was needed. More robust (and dearer) headlamps are available ready-made through caving groups and from safety equipment shops supplying the mining industry.

Bob Mesibov
Research Associate, QVMAG

References:

Mesibov, R. 1991. Species-level Comparison of Litter Invertebrates at Two Rainforest Sites in Tasmania. Unpublished report for the Plomley Foundation. [Now published as: Mesibov, R. 1998. Species-level comparison of litter invertebrates at two rainforest sites in Tasmania. Tasforests 10: 141-157.]

Mesibov, R. 1993. Species-Level Comparison of Litter Invertebrates from Three Vegetation Types in Northwest Tasmania. Tasmanian NRCP Technical Report No. 13. Forestry Commission, Tasmania, and Department of Environment, Sport and Territories, Canberra.

Moeed, A. and Meads, M.J. 1983. Invertebrate fauna of four tree species in Orongorongo Valley, New Zealand, as revealed by trunk traps. New Zealand Journal of Ecology 6: 3-53.

A first sighting?
Invertebrata 5, Spring/Summer 1995/96

Some years ago the State Library of Tasmania produced a facsimile and transcription of 'Workbook No. 2 (17 May - 26 July 1826)' of the Van Diemen's Land Company surveyor Henry Hellyer. On 20 May 1826, Hellyer and his companions were exploring the country around Port Sorell on Tasmania's north coast, and the 'Workbook' records Hellyer's observation of mud chimneys made by burrowing parastacid crayfish (Engaeus).

The facsimile is reproduced below. Notice that Hellyer first calls the structures 'anthills', then corrects that to 'land crab chimnies.' Did he dig out a burrow to see what had made the chimney, or was he put right by a bush-wise member of his party? Is this the first recorded observation of such structures in Australia?

Bob Mesibov
Research Associate, Zoology, QVMAG

The text reads: "Saturday May 20th The PackHorse being much galled we divided his load by putting part on another horse & started at 9 o'clock Went N 3 Miles thro Forest with much scrub & at 10 am to 11 ascended a Ridge of Rocks with very few Trees on which we went till 1/4 to 1 saw curious anthills [crossed out] land crab chimnies a dwarf kind of Mimosa yellow in bloom here very much enlivened the appearance of the Country Went on ascending & descending through Forest & scrub 3 Miles in a NW directn till [illegible] 2 when having arrived at the top of a lofty ridge of small Trees so thick, our Horses pushed them down right & left with great labor, we were anxious to see how far the Sea was from us Thompson ascended a Tree & told us he saw the [etc]"

Rediscovery of the Lake Fenton Funnelweb
Invertebrata 5, Spring/Summer 1995/96

The Tasmanian Museum is now the proud owner of a live female Alpine Funnelweb Spider, Plesiothele hickmani (Hickman, 1935). In the booklet Native invertebrates which are rare or threatened in Tasmania, P. fentoni is listed as extinct. In late June 1995, Dr Robert Raven returned with Maria Moore to the type localities and recorded that the species was still reasonably abundant at these sites.

Small for most funnelweb spiders, the holotype male measures 11.0 mm in total length, excluding chelicerae and spinnerets. The allotype female is 15.0 mm in length. The carapace is medium brown with a brown abdomen. The dorsal surface of the male is marked with five pairs of dark oblique stripes and a median stripe. The abdomen of the female is more yellowish-brown with a median black stripe, which becomes narrower posteriorly, with six pairs of greyish-black oblique stripes on the sides.

The habitat of this species is in moss growing on well-drained boulders at Lake Fenton, Mt Field National Park. It seems to require a moss depth of at least 10 cm. Burrows are simple and lined with silk, without a lid, and are fairly numerous in mossy boulders among the deciduous beeches Nothofagus gunnii and the grass-trees Richea pandanifolia near the spillway from Lake Fenton. Other individuals were found along the creekline from Lake Fenton, in the boulder field, on a south-facing slope.

The holotype male and allotype female are lodged in the Australian Museum, Sydney. The Tasmanian Museum's female will eventually be placed in the TMAG collection.

Elizabeth Turner
Invertebrate Zoology, TMAG

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