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You are here: Home / 2019 / Archives for June 2019

Archives for June 2019

Croaking Science: Ancient giants – new insight into the largest living salamanders

June 29, 2019 by editor

Cryptobranchids are giant salamanders which inhabit cool, flowing freshwater in Japan, China and North America. They are an ancient group and are regarded as living fossils that have remained little changed for over 160 million years (Gao & Shubin, 2003). There are just three known species within two genera, all of which are classified as Threatened or Near Threatened. The Chinese giant salamander (Andrias davidianus) is the largest in the world growing to 1.7 m in length and weighing up to 60 kg (Murphy et al., 2000) (Figure 1). This species is Critically Endangered due to threats from over-harvesting and habitat destruction. The Japanese giant salamander (Andrias japonicus) is a closely related species and is slightly smaller than A. davidianus. Although classified at Near Threatened by the IUCN, its habitat is highly fragmented and populations are declining in many parts of its range (Kaneko & Matsui, 2004). The North American hellbender (Cryptobranchus alleganiensis) is the largest salamander in North America, reaching up to 74 cm in length (AmphibiaWeb, 2019). All giant salamanders live secretive lives but have similar ecology and biology, which includes extreme longevity (up to 60 years), parental care by males, and large larvae. However, there are differences in their habitats, diets, reproductive behaviour, egg size and mating strategies (Lou et al., 2018). Although various studies have been carried out on these species, their behaviour and ecology is still poorly understood, and often published research is in national languages which is not readily accessible. Also, much evidence of their behaviour is through occasional observations and not systematic studies (Lou et al., 2018). In this article we highlight some recent research findings of these unusual and important species.

Figure 1. The Chinese giant salamander is the largest salamander in the world growing up to 1.7 metres long. [Photo credit: J. Patrick Fischer; https://commons.wikimedia.org/wiki/File:2009_Andrias_davidianus.JPG]

All three species of giant salamander exhibit paternal care with the male guarding eggs, spending considerable time tail fanning and agitating eggs (Okada et al., 2015) (Figure 2). The first systematic study providing data on paternal from a North American hellbender nest was carried out by Settle et al. (2018). The researchers used unique underwater infra-red video cameras to the record behaviour of a male hellbender in his aquatic nest for a period of five weeks during the breeding season. In this study the male spent 98.4% of the 41.7 hours of observable footage guarding the eggs, rarely leaving them for the whole five week period (Settle et al., 2018). Interestingly, the male was observed to consume its own eggs (filial cannibalism) on seven occasions. The reasons for this are unknown but may either be due to the nutritional value of eggs to the male, or removing eggs that had been contaminated by a fungal infection (Settle et al., 2018). As in other giant salamander species, the male hellbender spent considerable time (60%) fanning the eggs. This is thought to increase oxygen levels in the water and prevent embryo mortality. Overall, this study highlights that male guarding of eggs in hellbenders increases survival of the eggs through decreased predation, increased oxygen levels and potentially removing diseased or dead eggs from the clutch. However, this high level of male guarding comes with several costs including low rate of feeding by the male and increased energy expenditure. Population declines of this North American hellbender could alter the relative costs and benefits of male parental care and impact on survival of populations (Settle et al., 2018).

Figure 2. Male Japanese giant salamander in his nest guarding the developing larvae. This male is spitting out a larva which had previously entered his mouth. [Photo credit: Takahashi et al. (2017).]

Recently, a new species of leech (Placobdella appalachiensis) and an unknown species of parasitic trypanosome (Trypanosoma sp.), have been found in a population of hellbenders from eastern North America (Hopkins et al., 2014). Research by DuRant et al. (2015) showed that hellbenders infected by leeches had altered physiology compared to unaffected hellbenders. Leeches dampened the immune response of the salamanders, increasing levels of trypanosome infection. In addition, infection with leeches altered the circadian rhythms of the salamanders which impacted on metabolic processes, foraging behaviour and social interactions, particularly during the time of the year when hellbender activity increases as a result of the onset of breeding (DuRant et al., 2015). It is thought that leech saliva directly impacts on the salamander’s physiology since it is known to contain many different hormones and neurosignalling molecules that are believed to directly affect the salamander’s responses to infection. Understanding the dynamics between the leech species to hellbenders is important for conservation of hellbenders which are declining throughout its range. The findings from this study increase our understanding of the physiological effects of leeches on hellbenders and future research needs to examine the possible impacts on reproduction which may influence conservation efforts.

Understanding the longevity of declining species is crucial and provides important information for conservation, such as total lifespan, age of sexual maturity, and age structure of populations in the field (Yamasaki et al., 2017). However, research on longevity in the Japanese giant salamander is lacking since it is not possible to determine age from weight or length. The only reliable method to determine age in salamanders is through skeletochronology. This method is based on the presence of growth layers recorded in cross sections of long bones (Halliday & Verrell, 1988). By taking cross sections of toes, it is possible to count the layers and thus calculate the age of an individual (Figure 3). Yamasaki et al. (2017) are the first researchers to successfully use skeletochronology to estimate age in the Japanese giant salamander. In this study hellbenders lived up to 11 years. Anecdotal observations suggest that this species may live up to 60 years, but this is based on captive specimens. Long-lived species have slow growth rates and long generation times which means they are slow to adapt to environmental change. Therefore further studies on this species will help understand maximum life span and will have implications for conservation of this declining species.

Figure 3. Growth rings in the Japanese giant salamander. This individual was 11 years old. [Photo credit: Yamasaki et al. (2017)]

References

AmphibiaWeb (2019) Cryptobranchus alleganiensis: Hellbender <http://amphibiaweb.org/species/3861> University of California, Berkeley, CA, USA. Accessed 21 June, 2019.

DuRant, S., Hopkins, W. A., Davis, A. K. & Romero, M. (2015) Evidence of ectoparasite-induced endocrine disruption in an imperilled giant salamander, the eastern hellbender (Cryptobranchus alleganiensis). The Journal of Experimental Biology, 218: 2297-2304. doi:10.1242/jeb.118703.

Gao, K. & Shubin, N. (2003) Earliest known crown-group salamanders. Nature, 422: 424-428.

Halliday, T. R. & Verrell, P. A. (1988) Body size and age in amphibians and reptiles. Journal of Herpetology, 22 (3): 253-265.

Hopkins, W. A., Moser, W. E., Garst, D. W., Richardson, D. J., Hammond, C. I. & Lazo-Wasem, E. A. (2014) Morphological and molecular characterization of a new species of leech (Glossiphoniidae, Hirudinida): implications for the health of its imperilled amphibian host (Cryptobranchus alleganiensis). ZooKeys, 378: 83-101.

Kaneko, Y. & Matsui, M. (2004) Andrias japonicus. The IUCN Red List of Threatened Species 2004: e.T1273A3376261. http://dx.doi.org/10.2305/IUCN.UK.2004.RLTS.T1273A3376261.en. Downloaded on 21 June 2019.

Luo, Q., Tong, F., Song, Y., Wang, H., Du, M. & Ji, H. (2018) Observation of the breeding behavior of the Chinese giant salamander (Andrias davidianus) using a digital monitoring system. Animals, 8: 161. doi:10.3390/ani8100161.

Murphy, R. W., Fu, J. Z., Upton, D. E., De, L. T. & Zhao, E. M. (2000) Genetic variability among endangered Chinese giant salamanders, Andrias davidianus. Molecular Ecology, 9: 1539–1547.

Okada, S., Fukuda, Y., & Takahashi, M. K. (2015) Paternal care behaviors of Japanese giant salamander Andrias japonicus in natural populations. Journal of Ethology, 33: 1–7.

Settle, R. A., Briggler, J. T. & Mathis, A. (2018) A quantitative field study of paternal care in Ozark hellbenders, North America’s giant salamanders. Journal of Ethology, 36: 235–242 https://doi.org/10.1007/s10164-018-0553-0.

Takahashi, M. K., Okada, S. & Fukuda, Y. (2017) From embryos to larvae: seven-month-long paternal care by male Japanese giant salamander. Journal of Zoology, 302: 24–31. Yamasaki, H., Taguchi, Y., Minami, S., Kuwabara, K. & Shimizu, N. (2017) Age determination by skeletochronology of the Japanese giant salamander Andrias japonicus (Amphibia, Urodela). Bulletin of the Hiroshima University Museum, 9: 41-47

Filed Under: Uncategorized Tagged With: ancient, Croaks, giant salamanders, paternal care

What our animals are up to this month…

June 29, 2019 by editor

What our animals are up to this month… July 2019 edition

In the amphibian world, newts may be seen during a period of transition in July. Some adult newts may still be present in ponds during this time, while others may be moving to terrestrial areas. Developing larvae will be exclusively in freshwater habitats until reaching metamorphosis.

In the reptile world, this is an important month for our slow-worms.  Female slow-worms will be gravid and carrying developing young inside their bodies from July – September. Slow-worms bask even more than usual during this period in order to help along the development of young inside their bodies and may be found under objects that heat up from the sun’s energy.  But with the strong need to bask, we may also see our legless lizards out in the open, using roads or paths to gain more warmth. Females carrying developing young will appear larger than your average slow-worm with young slow-worms being live-birthed in August to mid-September. The gold or silver juveniles, measuring only 4cm long, will break through their egg membrane and remain active until temperatures lower in the autumn.

To find out more about our species, click here.

Remember to record your sightings on our free Dragon Finder app.

Female slow-worms carrying young are more likely to be basking out in the open during the summer months

Filed Under: Uncategorized Tagged With: slow-worm

Animation (voiced by Stephen Fry) Highlights the Devastation of Ranavirus

June 26, 2019 by editor

Comedian, author, writer and frog enthusiast Stephen Fry has lent his voice to an emotive new animation created by international conservation charity ZSL (Zoological Society of London), hoping to raise the profile of the deadly Ranavirus threatening UK common frogs.

Introduced to Great Britain by humans in the 1980s, Ranavirus mainly affects common frogs (Rana temporaria) but also affects other amphibians and could affect fish and reptiles. Research from ZSL, which formed the basis of the film’s content, found that at least 20% of Ranavirus cases over the past 30 years could be attributed to human-caused introductions such as pond owners introducing fish, frog spawn or plants from other environments.

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Stephen Price, amphibian disease expert at ZSL’s Institute of Zoology and UCL said: “Having studied Ranavirus for more than a decade, it was becoming ever more apparent that we needed to do something different to get people‘s attention and alert them to this deadly disease unfolding in their back gardens – because they can do something about it. People can help stop the spread by avoiding moving potentially infected material such as spawn, tadpoles, pond water and plants into their own pond. Disinfecting footwear or pond nets before using them in other water bodies will also help, while building wildlife ponds that mimic more natural freshwater habitats, which provide shade, will help frogs to keep cool and therefore lower the severity of the disease.”

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Amphibians are vital to the world’s ecosystems, they are one of the most incredibly diverse forms of life, found almost everywhere. They are essential components of food webs; frogs and newts keep the insect and slug populations in check and serve as prey for foxes and birds. Without frogs, localised ecological collapse could follow.

Members of the public can assist by reporting sick or dead amphibians to ZSL’s Garden Wildlife Health Project, which helps track diseases affecting British garden wildlife:www.gardenwildlifehealth.org

For information on what Froglife are doing to tackle amphibian diseases, take a look here. 

Take a look at ZSL’s Ranavirus fact sheet here.

Watch the animation narrated by Stephen Fry below:

 

Filed Under: Uncategorized Tagged With: CommonFrog, disease, GWH, Ranavirus, ZSL

CJ Wildlife – Your garden in June

June 1, 2019 by editor

This month, CJ Wildlife – Europe’s leading garden wildlife specialist and Froglife partner are reminding us that all of our gardens, no matter what size, can become bustling nature reserves for our local wildlife.

As June arrives you may start to notice a new crop of fledglings that have left the nest and are noisily making their way to independence.  Young frogs and toads will start to leave ponds this month, continuing the journey from tadpole to adult, and will move into long grass and quiet corners to feed and grow until the autumn. The same areas are also used by lizards, slow worms, hedgehogs and other wildlife. It’s also a busy time for female hedgehogs as they will begin to give birth, so you may spot a hoglet or two in your garden or local area.

Things to do in your garden this month:

  • Keep birdfeeders clean and topped up in preparation for new fledglings.
  • Provide live foods to help busy adults and hungry juveniles as they learn to fend for themselves. 
  • Provide a source of clean drinking and bathing water for garden birds and wildlife.
  • Tread carefully in the long grass – particularly if you’re using a strimmer!  The vegetation could be concealing hedgehogs and their youngsters, plus frogs, toads and newts, not to mention reptiles such as slow worms or, if you’re very lucky, a grass snake. 
  • Be aware of potential fledgling traps such as loose fruit netting, open water butts, steep-sided ponds and, of course, pet cats.
  • Add a frog and toad house to your garden, these houses will provide a cool dark area for these creatures to shelter during warmer days.
  • If you have hedgehogs now is a great time to provide them with a reliable source of food as they are likely to be caring for young.

For more hints and tips on making the perfect wildlife garden this summer, visit www.birdfood.co.uk, plus as a Froglife supporter, you can save 10% off when you buy from CJ Wildlife, simply use discount code UKFROG18 when you order.

Filed Under: Uncategorized Tagged With: CJ Wildlife

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