The Thickness of the Flat Periwinkle Shell

Flat Periwinkle, Littorina obtusata

The flat periwinkle Littorina obtusata is a very common grazer of seaweeds on the middle shore around Ireland (1) and is a large constituent of the diet of the common shore crab Carcinus maenas (2). C. maenus feeds on the shellfish by crushing the shell and extracting the periwinkle. The evolution of the shell is though to be driven mainly by the selection pressures associated with such shell crushing predators (3). However Geoffery Trussell proposes that morphological co-evolution between predators and their gastropod prey may be driven by natural selection on reaction norms rather than genetically fixed phenotypes (4). In his study of geographical variation in L. obtusata in the Gulf of Maine, he found that periwinkles in areas with more C. maenas had thicker shells. This result was underlined in a subsequent laboratory experiment when L. obtusata raised in the presence of C. maenas again had much thicker shells. The trade off for better protection was smaller individuals with an accompanied reduction in body growth.

Shore Crab, Carcinus maenas

References:

1. Chinery 1987, Field Guide to the Wildlife of Britain and Europe p. 200
2. Ropes 1968, Fishery Bulletin 67 pp. 183-203
3. Clements et al. 2008, Biology Letters 4 pp. 179–182
4. Trussell 2000, Evolutionary Ecology Research 2 pp. 803-822

How to Eat an Insect

A common sight on bogs and heaths throughout west Cork and Kerry, the Large Flowered Butterwort (Pinguicula grandiflora) is one of a number of carnivorous plants native to Ireland (1). On these poorer, wetter soils, carnivory offers an advantage to plants (2) and makes them indicative of such wet soils. Due to the low pH of peaty soils, nutrients become unavailable to plants as they become bound in salts. While it was previously held that the main reason for insectivorous behaviour in plants was to obtain mainly nitrogen (3), it has been shown that in a Pinguicula species, only phosphorus absorbed through the leaves leads to a significant increase in plant biomass (4).

Large Flowered Butterwort, Pinguicula grandiflora

 
So how does P. grandiflora capture insects to eat? The leaves of the plant carry a number of cells that are devoted to this task: secretory head cells, endodermal intervening cells and basal reservoir cells (5). The head cells hold drops of mucilaginous secretions which attract and then trap the insect prey. Further incapacitation is achieved by release of more mucilage from the reservoir cells. Digestion can then begin by the release of enzymes from the endodermal-like cells.

References:

1. Phillips, 1977 Wild Flowers of Britain p. 46
2. Brewer et al., 2010 Aquatic Biology In Press, Corrected Proof
3. Thompson, 1981 Biological Journal of the Linnean Society 16 pp. 147-155
4. Karlsson and Carlsson, 1984 New Phytologist 97 pp. 25-30
5. Heslop-Harrison, 1981 Annals of Botany 47 pp. 293-319

The Brittle Star Link

Two Small Common Brittle Stars, Ophiothrix fragilis

The Common Brittle Star (Ophiothrix fragilis) is a widespread invertebrate of European waters. It has a body comprising of a central, flattened disc from which five narrow arms radiate (1). Dense beds of O. fragilis are quite common in European waters, often of up to 2000 individuals m^-2 (2). Their suspension feeding action means that they remove and recycle organic material in the water, and as such provide an important link between benthic and pelagic ecosystems (3).

References:

1. Sterry, 2004 Collins Complete Guide to Irish Wildilfe p. 176
2. Broom, 1975 Journal of the Marine Biological Association of the UK 55 pp. 191-197
3. Allen, 1998 Marine Biology 132 pp. 383-390

Arabian Oryx

A guest post by Ken.

During a recent bout of 'dune-bashing' in the Dubai Desert Conservation Reserve, I came upon a herd of Arabian Oryxes (Oryx leucoryx). Our guide, a man from Burundi (where they have all the usual African wildlife except for elephants he informed me), who had been giving the safari for ten years was quick to spot them. He said this was a rare sight. The Dubai desert plains can reach temperatures of up to high 40's. However, by the time I was there in November it was down to low 30's. It had also just rained heavily, another unusual sight in the Emirate of Dubai in the U.A.E. This maybe why we were graced with a glimpse. I quickly grabbed my sister's camera to take a few pictures.

Dune Bashing

O. leucoryx are the most easterly-ranging oryxes and are native to Arabia and Iraq. They usually live in deserts, arid plains and rocky hill-sides. Both sexes have straight horns with the female's horns usually being longer and more slender. The mane extends from the shoulders and they possess a slightly tufted tail. The head and body are pale with definite markings of black or brown. They roam in herds of two to a dozen and are always alert and vigilant. If injured or confronted by their natural predators they attack with lowered heads with the horns pointed dangerously forward. They eat primarily grasses and shrubs using streams and waterholes as a source of water. However they can obtain water from desert fruit or succulent bulbs (1).

A herd of wild Arabian oryxes (Oryx leucoryx)

The species was eradicated entirely from the Arabian Peninsula by 1972 due to over-hunting and poaching. Prior to the extirpation, however, several captive breeding programs were started with the intention to reestablish them in their native habitats. Ismail et al. show that the frequency of reproductive activity was significantly related to daytime, temperature and radiation with significant reduction during a drought period. Also extreme climatic events, suitability of habitat aswell as carry capacity must be taken into account when managing introduced populations of desert ungulates in fenced protected areas (2).

Check out my white socks!!!

And then they were gone. Although we slowed down so as not to frighten them too much, we eventually went our separate ways. And for now, at least, we can be certain that the Arabian Oryx is alive and well.

References:

1. Biological Conservation, Volume 1, Issue 2, January 1969, Page 129
2. K. Ismail, K. Kamal, M. Plath, T. Wronski, Effects of an exceptional drought on daily activity patterns, reproductive behaviour, and reproductive success of reintroduced Arabian oryx (Oryx leucoryx), Journal of Arid Environments, In Press, Corrected Proof, Available online 29 October 2010

Hermit Crabs Prefer Winkle Shells

Pagurus bernhardus, the Common Hermit Crab

Pagurus bernhardus, the Common Hermit Crab, is a scavenger of sheltered shores, and is the most common hermit crab in Irish waters. It can often be spotted in rock pools, seen as a seashell with legs scurrying into corners. It has, along with all the hermit crabs, the last thoracic plate on the ventral side free of the carapace (1) and because of this, P. bernhardus lives inside the empty shells of molluscs, exchanging the shells for larger ones as the animal grows. The fifth pair of walking legs are also reduced to allow it to fit into the shell which also allows the animal to grip the inside of the shell (2) and the right handed pincer is larger than the left to block the shell entrance when the crab retreats inside (3). It has been suggested that hermit crabs originated from crevice dwlling ancestors, which had progressively lost their abdominal calcification, and took to using empty mollusc shells due to their mobility (4).

Pagurus bernhardus emerging from Edible Periwinkle (Littorina littorea) shell

Young P. bernhardus individuals have a marked preference for winkle shells, both Littorina littorea (Edible Periwinkle) (5) and L. obtusata (Flat Perieinkle) (6) over Gibbula spp. (Whelk) shells. This preference may be due to a number of factors, such as greater ease of locomotion and ease of manipulation during mating, and does have an effect on the overall performance of an individual. A 1995 survey of female P. bernhardus individuals showed that those living in the preferred shells produced eggs earlier in the season, produced more eggs in the first brood, and produced a second brood more often than did females in the less preferred shells (6). However it was unclear whether this reflected a reduced capacity for mating or if competition for the best shells resulted in low quality crabs occupying the less preferred ones.

Pagurus bernhardus, the Common Hermit Crab. Note the difference in size of the pincers

References

1. Lancaster, 1988 Field Studies 7 pp. 189-238
2. Challinor et al., 1999 A Beginner's Guide to Ireland's Seashore p. 142
3. Sterry, 2004 Collins Complete Guide to Irish Wildilfe p. 168
4. McLaughlin, 1983 Journal of Crustacean Biology 3 608-621
5. Elwood et al., 1979 Animal Behaviour 27 pp. 940-946
6. Elwood et al., 1995 Marine Biology 123 pp. 431-434

A Delicate Beauty

Tunbridge Filmy Fern (Hymenophyllum tunbrigense)

Hiding among the moss, blending in to such an extent that it can be easily mistaken for one of them, the Tunbridge Filmy Fern (Hymenophyllum tunbrigense) has a diaphanous magnificence. It grows in shady habitats, forming a mat when growing, either vertically or at an incline, against rocks or tree trunks by streams or under dripping water (1). It has numerous, overlapping leaves which have multiple pinnae. These arise from slender rhizomes which are much-branched (2). Tunbridge Filmy Fern is very similar in appearance to Wilson's Filmy Fern (H. wilsonii), but both are found at different elevations: Wilson'd Filmy Fern tends to be found on mountain tops, while Tunbridge Filmy Fern inhabits lowland or slightly elevated wooded glens (3). This difference in locality is due in part to the different light requirements for the two species, with Tunbridge Filmy Fern having a lower light requirement than Wilson's Filmy Fern (4). Tunbridge Filmy Ferns is a very long lived species, with some colonies being 200 years old.

Tunbridge Filmy Fern (Hymenophyllum tunbrigense)

References

1. Phillips, 1980 Grasses, Ferns, Mosses and Lichens of Great Britain and Ireland p. 108
2. Richards and Evans, 1958 Journal of Ecology p. 245
3. O'Mahony, 2009 Wildflowers of Cork City and County p. 323
4. Proctor , 2003 Annals of Botany 91 pp. 717-727

Brown Seaweeds of Kelp Beds

Laminaria hyperborea

Laminaria hyperborea

Holdfast of Laminaria hyperborea

Laminaria digitata

Laminaria digitata

Holdfast of Laminaria digitata

Saccharina latissima

Saccharina latissima

Frond of Saccharina latissima

Holdfast of Saccharina latissima

Saccorhiza polyschides

Saccorhiza polyschides

Holdfast of Saccorhiza polyschides

Flight of the Butterfly

Red Admiral, Vanessa atlanta

One of the larger butterflies top be seen in Ireland, the Red Admiral (Vanessa atlanta) is a common sight of meadows, hedgerows and gardens with red bands and white spots contrasting boldly with its black upperwings (1). V. atlanta can be seen from May onwards in Ireland, with some individuals hibernating through the winter (2). Most, however, migrate from central and southern Europe to escape the summer droughts of these areas (3). Nettles (Urtica doica) are the food of choice of the larvae and these have begun to wither when migration begins. When the butterflies arrive in the north, there is a plentiful supply of food. Most adults will return south in late September to mid November when nettles are again in good supply.

Red Admiral, Vanessa atlanta

When returning south, V. atlanta engages in a high elevation return at a reported altitude of 2000 meters (3), riding on cool northerly winds. While flying it generates large forces that cannot be accounted for by conventional steady-state aerodynamics, as do all insects. Investigations into V. atlanta flight using wind tunnels and smoke-wire flow visualisations show that they use a variety of unconventional aerodynamic mechanisms to generate force, often different mechanisms in successive strokes (4)

References

1. Sterry, 2004 Collins Complete Guide to the Irish Wildlife p. 104
2. Chinery, 1987 Field Guide to the Wildlife of Britain and Europe p. 234
3. Mikkola, 2003 European Journal of Entomology 100 pp. 625-626
4. Srygley and Thomas, 2002  Nature 420 pp. 660-664

Blennies Seek Out the Dark

The Blenny (or Shanny, Lipophyris pholis) is a very common fish of the the North East Atlantic from Norway to Mauritania and the Atlantic islands, with some records in the Western Mediterranean (1). It is particularly widespread on the Western coast of Ireland. Found among stones and seaweeds in rocky gullies on the lower shore, it often becomes trapped in rock pools at low tide where the specimen pictured was spotted. While this is a small (c. 4 cm) example of the species, they can reach 10 cm in size (2).

Blenny, Lipophyris pholis, in a rock pool

Blennies show a preference for rocky over sandy substrata from an early age (3). The reason for this is unclear, but in such environments, Blennies will immediately make for the first dark area as soon as possible. Dodd et al. (4) have shown that in an artificial novel environment, they will move towards a black screen, pressing themselves up against it. Once they have gained experience of this environment, they will us the positions of large objects around them to relocate a refuge.

References

1. Steffani et al., 2006 Molecular Phylogenetics and Evolution 39 pp. 282–287
2. Sterry, 2003 Collins Complete Guide to Irish Wildlife p. 102
3. Almada and Faria, 2000 Journal of the Marine Biological Association of the UK 80 pp. 1143-1144
4. Dodd et al., 2000 Behavioural Processes 49 pp. 69-75

Sponge Repair

The Breadcrumb Sponge, Halichondria panicea

Probably the most common sponge to be seen on Irish seashores is the Breadcrumb Sponge, Halichondria panicea. It can be seen on the lower shore, varying in colour from yellow to green, with crater like openings dotting the surface (1). These are the exhalent openings through which seawater passes.

The Breadcrumb Sponge, Halichondria panicea

H. panicea is predated by a number of organisms, generally molluscan (2). It is also prone to wave damage due to its frequent position on rock faces on the lower shore and these two destructive forces pose a real problem for the sponge. Yet it persists, often in large amounts. This is due to its incredible regenerative abilities. Simulation of feeding in H. panicea by creating grooves in the sponge resulted in high growth rates in these areas, with most of the damaged area being recovered within 4 weeks (3).

References 

1. Challinor et al., 1999 A Beginner's Guide to Ireland's Seashore p. 71
2.  Knowlton and Highsmith, 2000 Marine Ecology Progress Series 197 pp. 285-291
3. Knowlton and Highsmith, 2005 Journal of Experimental Marine Biology and Ecology 327 pp. 36-46

Antimicrobial Synergism and the Spindle Tree

Fruit of Spindle Tree, Euonymus europaeus

Though the fine weather of the summer has given way to storm warnings and cold, dark mornings, its memory still lingers in the fruit of the Spindle Tree (Euonymus europaeus). This native shrub usually produces very distinctive, shocking pink, three to four lobed fruit from September to October (1) that is quickly eaten by blackbirds. This year, the summer has given a plentiful harvest of fruit that has until now meant many E. europaeus berries have gone untouched.

Spindle Tree, Euonymus europaeus

E. europaeus has proved to be quite useful: its hard timber was used to make skewers and spindles for spinning wool (hence the common name (1)). It has also been shown to produce secondary metabolites with remarkable antimicrobial abilities. Van den Bergh et al. (2) isolated a hevein-type antimicrobial peptide in 2002 from the bark of E. europaeus that show excellent antimicrobial activity against plant pathogenic fungi such as Fusarium oxysporum, Pythium ultimum and Rhizoctonia solani and Gram-positive bacteria such as Bacillus megaterium. This E. europaeus chitin-binding protein or Ee-CBP was also shown to be very stable as activity was not affected by boiling for ten minutes or prolonged storage.

Bark of Spindle Tree, Euonymus europaeus

A  further chitin binding protein was also isolated (3) that acted as a classical class I chitinase (Ee-chitinase) which was not as potent as the Ee-CBP. However, the Ee-CBP and Ee-chitinase displayed a pronounced synergistic effect in assays against fungal activity. These proteins have potential to be used in genetic engineering for biological control of plant diseases.

References

1. Phillips, 1978 Wild Flowers of Britain pp. 58 and 172
2. Van den Bergh et al., 2002 FEBS Letters 530 pp. 181-185
3. Van den Bergh et al., 2004 Planta 219 pp. 221–232

Roman with the Fallow Deer

Fallow Deer, Dama dama

The Fallow Deer (Dama dama) is the most common deer in Ireland. It is not a native species, having been introduced by the Normans to the Royal Deer Forest in Glencree, Co. Wicklow in 1244 (1). The deer is originally from the Eastern Mediterranean, and has been transported by humans throughout Europe, Africa, America and Australasia (2). One of the earliest translocations has been traced to the Neolithic period when animals were introduced to Rhodes (3). Movement of the animals throughout Europe has been attributed to the Normans (4), but Sykes et al. (5) suggest that the Romans were also a force in distributing D. dama across Europe. Analysis of remains found in 2003 at a Roman settlement at Monkton on the Isle of Thanet, Kent in England showed that it was highly likely that herds of D. dama existed here during Roman times.

Fallow Deer, Dama dama

References

1. Nolan and Walsh, 2005 Wild Deer Management in Ireland: Stalker Training Manual
2. Chapman and Chapman, 1975 Fallow Deer: Their History, Distribution and Biology
3. Masseti et al., 2006  Human Evolution 21 pp. 167–176
4. Sykes, 2007 British Archaeological Report, International Series 1656
5. Skyes et al., 2011 Journal of Archaeological Science 38 pp. 156-165

The Ability of Nostoc commune to Resist Dessication

Nostoc commune

The cosmopolitan cyanobacteria Nostoc commune is found on all continents, in all conditions, from tropical rain forests to the poles (Whitton and Potts, 2000 Ecology of Cyanobacteria: their Diversity in Time and Space). It is a common pest of gardens, associated with areas of poor drainage and/or poor nutrients, often forming masses of gelatinous, globular, brown-green colonies. These are composed of filaments of cells surrounded by a sheath. In the past, these colonies were believed to have fallen from the sky and were referred to as, among other things, “Sternschnuppen” (shooting stars) (Potts, 1997 International journal of Systemic Bacteriology p. 584).

Nostoc commune in a dessicated state

N. commune shows a remarkable capacity to resist desiccation, being able to survive storage at -400 MPa (0% relative humidity) for centuries (Potts, 1994 Microbiology Reviews 58 pp. 755–805). Prior to rehydration, N. commune appears as a brittle crust which increase in size rapidly upon the addition of water.

This remarkable ability is due to the presence of a viscous extracellular polysaccharide that is excreted by the cells. This glycan consist of a 1-4-linked xylogalactoglucan backbone with D-ribofuranose and 3-O-[(R)-1-carboxyethyl]-D-glucuronic acid (nosturonic acid) pendant groups (Helm et al., 2000 Journal of Bacteriology 182 pp. 974-982). Prevention of dessication is achieved by a number of processes. The glycan inhibits fusion of membrane vesicels during dessication (Hill et al., 1997 Journal of Applied Phycology 9 pp. 237–248). It also provides a structural and/or molecular scaffold with rheological properties which can accommodate the rapid biophysical and physiological changes in the community upon rehydration and during recovery from desiccation. The glycan matrix contains both lipid- and watersoluble UV radiation-absorbing pigments which protect the cell from photodegradation (Hill et al., 1994 Protoplasma 182 pp. 126–148). Finally although epiphytes colonize the surfaces of N. commune colonies, there is no penetration of the glycan due in part to a silicon- and calcium-rich pellicle and inherent resistance of the glycan to enzymatic breakdown.

Production of such an extracellular polysaccharide as this by N. commune may explain why microfossils of cyanobacteria are preserved so well from more than 3.5 billion years ago (Schopf and Klein, 1992 The Proterozoic Biosphere p. 185–193).

Snuff Said

Candle Snuff Fungus, Xylaria hypoxylon

To be found throughout the year, Candle Snuff fungus (Xylaria hypoxylon) is most visible now as most ground cover in the deciduous woodlands it is associated with has died back for the winter. It is cylindrical to flattened in shape, branching into an antler formation. The upper stromal surface is white and powdery and becomes black tipped at maturity. The lower, sterile parts are black and downy (Jordan, 2004 The Encyclopedia of Fungi of Britain and Europe p. 78).

Candle Snuff Fungus, Xylaria hypoxylon

Carabid Controller

The carabid beetle, Pterostichus madidus is a very common ground beetle that although being mainly active at night, is often seen in the day time if disturbed from under stones of logs. It is readily identified by its shiny, black body, the fine grooves in its elytra and its typically reddish legs (Sterry, 2004 Collins Complete Guide to Irish Wildlife p. 146). P. madidus is sometimes called the strawberry beetle as it feeds on strawberries as well as other fruit, but it is mainly carnivorous (Chinery, 1997 Collins Gem Insects, p. 129).

Pterostichus madidus

Quantitative ELISA analysis of crop content of the beetle has shown that quite a large proportion of its diet has consists of molluscs (Symondson and Liddell, 1993 Bulletin of Entomological Research 83 pp. 641-647). This feeding habit was shown to posit P. madidus as a potential biological control agent for slugs and snails by a glasshouse experiment (Asteraki, 1993 Entomophaga 38 193-198). This demonstrated that it controlled slug (Deroceras reticulatum) populations in a grass/clover sward. However Mair and Port (2001, Agricultural and Forest Entomology 3 pp. 99-106) have shown that the original serological tests may have been misleading as they showed that dead slugs were consumed by P. madidus in preference to live ones in laboratory conditions. Live slugs that were killed and consumed were quite small (<0.11 g). Yet the use of P. madidus to control molluscan pests is still a viable alternative to chemical means, as long as it is combined with methods to control the larger individuals.

Ascent of the Ascidians

Star Ascidian, Botryllus schlosseri

Phylogenetics is slowly rewriting our ideas of relationships between many organisms. Take for example the Ascidians. These tunicates (urochordates) were beliveved to once be a sister group of the vertebrates, due in part to the presence of characteristics such as segmented muscle (Lemaire et al., 2008 Current Biology 18 R620–R631). The lancelets (cephalochordates) were assumed to be the most closely related to the vertebrates as there are overall morphological similarlties and an increased complexity between these two groups when compared to the seemingly simpler tunicates. However in 2006, Delusc et al. (Nature, 23 pp. 965-968) analysed data from the sequencing of the tunicate Oikipleura dioica genome and found that tunicates represent the closest living relatives of vertebrates. Indeed, Delusc suggested that the lancelets be grouped with the echinoderms rather than than the tunicates or vertebrates.

Star Ascidian, Botryllus schlosseri

Botryllus schlosseri (Star Ascidian) is a cosmopolitan, colonial ascidian that is found encrusting on rocks, shells and large brown seaweeds (Challinor et al., 2003 A Beginner's Guide to Ireland's Seashore p. 74). It has been used for over 50 years in the laboratory as a model system for the study of blastogenesis, colony fusion and regeneration (Manni et al., 2007 Developmental Dynamics 236 pp. 335-52). It forms free living, pelagic larvae by sexual reproduction that attach to a substrate and in turn reproduce asexually to form colonies of numerous genetically identical zooids. Individuals are arranged around a common cloak siphon, thus forming the “star” of the common name.

Red Squirrels Have Come Back Before

Red Squirrel, Sciurus vulgaris

The Red Squirrel (Sciurus vulgaris) is the only native Irish squirrel and is easily recognisable by its orange-red fur and distinctive ear tufts. Its body is 20-28 cm in length and its tail is usually paler than its body (Sterry, 2004 Collins Complete Guide to Irish Wildlife p. 20). Its decline in Ireland in recent years has been well documented in the popular press. The most recent survey of S. vulgaris numbers by Carey et al. in 2007 showed no individuals in counties Meath or Westmeath and only a few records from Louth, Carlow and Kilkenny combined (The Irish Squirrel Survey 2007, COFORD). It is estimated that there are currently 40,000 individuals in the whole of Ireland (2008, National Parks and Wildlife and Environment and Heritage Service of Northern Ireland, All-Ireland Species Action Plan: Red Squirrel).

This decline has been blamed on the spread of the Grey Squirrel (S. carolinensis), a species introduced from America to Castle Forbes in Co. Longford in 1911. S. carolinensis is a larger animal than S. vulgaris (body length 25-30cm) and this, along with their wider dietary range allows them to outcompete the Red Squirrel. Woodland availability and woodland species composition also have an effect on S. vulagris numbers.

Yet S. vulgaris has experienced all of this before. In 16th century Ireland, a large part of the native woodlands were cleared, which possibly lead to the extinction of S. vulgaris. In the 1800s, individuals were translocated from Britain to Ireland, thus reintroducing the species (Barrington, 1880 Scientific Proceedings of the Royal Dublin Society 2 pp. 615-631). In 2003, 19 S. vulgaris individuals were successfully translocated to Derryclare, Connemara in western Galway, which prompted a further translocation of individuals to Belleck Forest Park in Co. Mayo (Finnegan, 2007 The Translocation of Red Squirrel (Sciurus vulgaris) to Belleek Forest Park, Mayo – Phase One).

The Shaggy Ink Cap is a Nematophage

Shaggy Ink Cap, Coprinus comatus

The Shaggy Ink Cap (or Lawyer's Wig, Coprinus comatus) is a large, gregarious basidiomycote fungus that is often collected from the wild and eaten. The fruiting body first appears as an oval structure with no visible stem. The cap is covered with shaggy pale white to brown scales. It pulls away from the stem, turning pink, then black. The cap then dissolves into a black ink-like fluid (Harding et al., 1996 How to Identify Edible Mushrooms p. 54).

Shaggy Ink Cap, Coprinus comatus with cap dissolving

C. comatus was assumed to be an excusively saphrophitic fungus. However, Luo et al. (2004 Mycologia 96 pp. 1218-1224) report on trapping, killing and feeding on two nematode species, the free living Panagrellus redivivus and the root-knot nematode, Meloidogyne arenaria by the fungus. It produces burr-like structures on sporophore-like branches called spiny balls that damage the nematode cuticle leading to leakage of the inner materials of nematodes (Luo et al., 2007 Applied and Environmental Microbiology 73 p. 3916-3923). In addition, C. comatus produces toxins that immobilise the nematodes. Once a nematode has been infected, it is digested and consumed within days. Hyphae then grow out of the nematode.

Enchantingly Perennial

Enchanter's Nightshade, Circaea lutetiana

Enchanter's Nightshade (Circaea lutetiana) is a delicate herb of damp woods, shady places and hedgerows on basic soil (Phillips, 1977 Wild Flowers of Britain p. 90). It has opposite pairs of oval leaves and bears flowers in loose spikes above the leaves. It exhibits a pseudo-annual life cycle: it is a perennial (clonal) plant that behaves as a vegetatively propagating annual (Verberg and During,  Plant Ecology 134 pp. 211-224). C. lutetiana completes its life cycle at the end of the summer, producing seeds or hibernacles from the rhizome apices. These hibernacles do not produce new ramets and remain dormant over winter, giving rise to new vegetative growth in the spring.

We Only Come Out at Night

Millipedes are important detritivors in most ecosystems as they promote the decomposition of dead plant material, thus stimulating microbial growth. Ingested leaf litter is particulated in the millipede gut, meaning that when egested as faeces more surface area is available for bacterial and fungal colonisation (Hopkin and Read, 1992 The Biology of Millipedes p. 4).

Tachypodoiulus niger

Two of the most common species of millipede found in Ireland are Tachypodoiulus niger and  Polydesmus angustus. T. niger is commonly known for its tendency to curl up like a spring when disturbed. It is often found under tree barks (Chinery, 1987 Field Guide to the Wildlife of Britain and Europe p. 275). P. angustus has a flattened body (earning it the common name Flat-Backed Millipede) and resembles a centipede, but its two pairs of legs per segment identifies it as a millipede (Sterry, 2004 Collins Complete Guide to Irish Wildlife p. 172).

Polydesmus angustus

Both of these species are quite numerous, for example making up to 50% of the April diet of starlings (Lindsey, 1939 The Wilson Bulletin 51 pp. 176-182), but are often inconspicuous due in part to their presence in leaf litter but also because they tend to be nocturnal animals. Banerjee (1967, Oikos 18 pp. 141-144) observed that both species are most active during darkness from one hour after sunset till one hour before sunrise. Activity extends into the afternoon in the summer months.

Is the Future to be Jellyfish?

Compass Jellyfish, Chrysaora hysoscella

Reduction in the numbers of fish due to commercial fishing activities combined with changes in climate mean that blooms of the Cnidarian subphylum Medusozoa (jellyfish) are becoming more frequent and more numerous (Mills, 2001 Hydrobiologia 451pp. 55–68). While Ctenophores are also on the increase (see here), the physical size of the larger Medusozoa pose a variety of problems for various industries, both direct marine and non. 

Common Jellyfish, Aurelia aurita

Lynam et al. (2006, Current Biology 16 pp. R493-R494) report on blooms of large jellyfish (>13 cm in diameter, such as Chrysaora hysoscella) in the heavily fished area of northern Benguela off the coast of Namibia, where jellyfish biomass (12 million tonnes) now exceeds that of fish (3.6 million tons). This increase has manifested itself in burst fishing nets, blockage of power station coolant intakes and blockage of alluvial sediment suction used in diamond suction. Similar nuisances are reported by Nagata et al. (2009, Pan-American Journal of Aquatic Sciences 4 pp. 312-325) in Southern Brazil where artisanal prawn fishermen noted shortening the duration of trawl hauls, displacement of hauls to areas further away from the landing ports and the necessity of changing to other fishing gear types.

Lion’s Mane Jellyfish, Cyanea capillata

Chessie Season

Flowers of the Horse Chestnut, Aesculus hippocastanum, in May

The Horse Chestnut, Aesculus hippocastanum, is an introduced deciduous tree originally used for decoration in avenues and gardens but now naturalised in woods throughout Ireland (Phillips, 1977 Wild Flowers of Britain pp. 38, 174) where it makes an attractive component of the country's hedge banks (O'Mahony, 2009 Wildflowers of Cork City and County p. 54). It is indigenous to the Balkan Penninsula and was brought to Vienna in 1576, via Constantinople, and onwards to Central and Western Europe (Avtzis et al., Sofia 2007 Phytologia Balcanica 13 pp. 183–187). It has a spreading habit and produces spikes of white to red flowers in April and May (Sterry, 2004 Collins Complete Guide to Irish Wildlife p. 182). The leaves are bright green and divided into 5-7 oval leaflets. A. hippocastanum is among the first trees to turn brown in the autumn.

Leaf of The Horse Chestnut, Aesculus hippocastanum

It is, however, because of its fruit that A. hipposcastanum is best known. These consist of a fleshy outer part that is usually covered in spikes and a glossy brown nut, commonly called conkers, chestnuts or 'chessies'. These were very mush sought after when I was a child and are used to play the game of Chessies (more commonly called Conkers). This involves drilling a hole in the chessie and threading a piece of string or shoe lace through it. One then challenges an opponent and both players take turns to crack the other's dangling chessie with one's own. The winner is that who cracks the others chessie. All sorts of underhand schemes were employed to become the victor, such as yanking the opponent's chessie from their grasp, throwing it to the floor and stamping on it and treating the nuts to make them stronger. Some of these preserving methods are outline by O'Hare and Gerrel (2000, New Scientist: The Last Word 2 pp. 7-11), including baking in the oven, pickling in vinegar, varnishing and even soaking in hand lotion.

Fruit of the Horse Chestnut, Aesculus hippocastanum, in September

Unfortunately A. hippocastanum in Europe is now under threat from a bleeding canker disease which causes bleeding cankers on the stem and branches, foliar discoloration, and crown dieback often leading to tree death (Green et al., 2010 PLoS ONE 5: e10224). This disease was first reported in 2002/3 and has since infected hundreds of thousands of European A. hippocastanum trees across several countries in northwest Europe (Forestry Commission, 2008 Report on the National Survey to Assess the Presence of Bleeding Canker of Horse Chestnut Trees in Great Britain). The causative agent is the bacterium Pseudomonas syringae pathovar aesculi. This pathogen is identical to a P. syringae pathovar that infects Indian horse chestnut (Aesculus indica), indicating that it has found a new host in A. hippocastanum - one in which it is aggressively spreading.

Fruit of the Horse Chestnut, Aesculus hippocastanum