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You are here: Home / 2020 / Archives for December 2020

Archives for December 2020

What our animals are doing this month….

December 21, 2020 by Mirran Trimble

As we welcome in the New Year, all of our native amphibians and reptiles should be safe and warm in their overwintering sites. The nature and quality of these sites can vary depending on what habitat is available nearby, but one species which doesn’t have to worry about finding a good spot is the Natterjack Toad. Instead, these resourceful toads create their own overwintering sites by digging burrows with their short, powerful legs. These burrows not only keep them warm throughout the cold winter months, but they also provide shade on hot summer days, and make a great hiding spot from predators.

Natterjack Toads are unusual amphibians in that they are specialised to living in coastal, heathland and saltmarsh habitats. The sandy soil in these environments is perfect for digging, and the warm, shallow coastal pools also provide ideal breeding habitat. Unfortunately, Natterjack Toads are rare in the UK and are threatened by the loss of coastal habitats. Protecting these habitats is crucial for the survival of these unique toads!

You can recognise rare Natterjack Toads by their short legs, green irises and the distinctive yellow line down the back!

Filed Under: What our animals are doing this month Tagged With: habitats, natterjack toad, overwintering, specialised

Croaking Science: Venomous Amphibians

December 21, 2020 by Xavier Mahele

Venomous animals are able to inject their toxins into another organism while poisons are ingested, inhaled and absorbed. The ability to deliver venom into another animal has distinct evolutionary advantages such as in defence, prey capture and even sexual selection.

Amphibians secrete a wide variety of compounds from their skin glands. Generally, mucous glands help provide a moist coating on their skin to facilitate cutaneous respiration while granular glands secrete substances that amphibians use as a chemical defence against predators (eg. toxic and noxious compounds) and microorganisms (eg. antimicrobial peptides). This is sometimes displayed with bright, aposematic colouration (Duellman and Trueb 1996). 

Many different toxic secretions have been found in amphibian skin which act in numerous ways to disrupt the physiology of potential enemies (Daly et al. 2005, Savitzky et al. 2012).  For example, newts in the genera Taricha and Notophthalmus synthesise tetrodotoxins in high concentrations and are co-evolving in an evolutionary arms race with Thamnophis garter snakes where toxicity is a selective pressure (Brodie et al. 2005, Mailho-Fontana et al. 2019, Hague et al. 2020).  Fire salamanders secrete samandarin alkaloids through their paratoid glands which can cause convulsions, hypertension and respiratory paralysis in potential predators.  Frogs can sequester an array of toxins such as the potent neurotoxin Zetekitoxin in the Panamanian golden frog and the batrachotoxins in highly toxic Phyllobates poison frogs (Duellman and Trueb 1996).  The bright yellow Australian corroboree frogs of the genus Pseudophryne synthesise their own pseudophrynamine toxins as well as sequestering pumiliotoxins from their environment to deter predators (Smith et al. 2002). Fossorial caecilians are also known to produce defensive toxins with poison glands being discovered on the tails of Siphonops annulatus ringed caecilians as a possible defence against predators as they burrow into the soil (Jared et al. 2019). 

Venom, however, is rare in amphibians with only a few species possessing a system to deliver their toxins into another organism. 

The Iberian ribbed newt (Pleurodeles waltii) is a fascinating salamandrid from Spain and Portugal with an incredible defence behaviour. They have the ability to use their ribs to protrude through the skin to envenomate and ‘sting’ a predator. When distressed these newts can flatten themselves or arch their backs in an antipredator posture. They will then rotate their ribs 65° forwards which increases the angle of the spine to allow its ribs to penetrate through the skin wall and project as ‘spines’. This allows them to coat their ribs with a viscous, milky substance from their skin tubercles and inject it into the mouth of the predator making them unpalatable and allowing them to escape (Heiss et al. 2010). This defence mechanism doesn’t cause any permanent damage as antimicrobial peptides are able to prevent infection in the lacerated skin and their tissue is able to regenerate remarkably quickly. The tip of the ribs are also covered with a periosteum layer which is also thought to prevent microbial infection when the ribs puncture the skin.

The Echinotriton genus of crocodile newts are a sister group to the sharp ribbed newt and are also able to use their ribs to pierce their body wall when attacked by predators (Brodie et al. 1984).  

Sharp ribbed newt (Pleurodeles walti)

Brazil is home to two tree frogs which have incredible cranial morphologies and venomous defensive mechanisms. The Greening’s frog Corythomantis greeningi live in the semi-arid caatinga ecosystem of Eastern Brazil and conceal themselves in tree hollows and rock crevices to stay moist and evade predators. Bruno’s casque headed frog Aparasphenodon brunoi is another endemic Brazilian hylid with a fascinating skull morphology. They inhabit lowland tropical forests and shrubland and like C. greeningi, will hide in water-filled tree or bamboo hollows and bromeliad phytotelmata. 

Both of these peculiar frogs have flattened, casqued heads with their skin co-ossified with underlying bones. They use their heads to aid in a behaviour known as phragmosis (Jared et al. 2006, Blotto et al. 2020).  Phragmosis occurs when an animal enters a hole and blocks the entrance with their head to defend themselves from predators. In the lab, these frogs will exhibit this behaviour by entering test tubes backwards and blocking themselves off with their casqued heads. This phragmotic behaviour along with their venomous spines means these frogs have never been observed being predated in the wild. It is also thought that cranial ossification and phragmosis also indirectly reduces water loss and prevents desiccation by creating a humid microclimate within their tree holes (Jared et al. 2006). 

These frogs have bony spines, ridges and protrusions on their skulls in areas with high concentrations of granular and mucous glands which secrete a potent venom. Their mobile heads allow the frogs to deliver the venom into animals via head-butting and jabbing with their spines which are coated with the toxic secretions as the spines pierce their venom glands. This provides a highly effective chemical defensive mechanism as the toxin coupled with the wound caused by the head spines ensures would-be predators have a bad time when they attempt to ingest these frogs (Jared et al. 2015). Their cutaneous secretions include alkaloids and steroids which can induce oedema and intense pain in predators (Mendes et al. 2016). The venom contains both proteolytic and fibrinolytic agents as well as hyaluronidase which aids the toxins in diffusing around their enemies’ bodies (Jared et al. 2015). 

The venom of Greening’s frog is thought to be twice as lethal as fer-de-lance snakes of the genus Bothrops while Bruno’s casque headed frog secretes a venom 25x as toxic as these notorious neotropical vipers with an LD50 of 94.8µg in mice. A single gram of A. brunoi venom could kill 300,000 mice or 80 humans (Jared et al. 2015)!  However, A. brunoi has smaller spines and granular glands than C. greening and so may not be able to inject as much venom when defending against a predator. 

Top: Bruno’s casque headed frog (Aparasphenodon brunoi) L: Renato Augusto Martins R: Carlos Jared 
Bottom: Greening’s frogs (Corythomantis greeningi) Carlos Jared 

 

There are many other frogs with complex cranial morphology including immense variation in skull shape and hyperossification which often relate to their interesting and diverse ecologies (Paluh et al. 2020). With an array of other anurans having mineralised and spiny skulls, it is possible that there are a few more venomous frogs which are waiting to be studied. Contenders include the fascinating shovelhead tree frog Triprion, the crowned tree frog Anotheca spinosa and Polypedates ranwellai (Jared et al. 2015). 

In a recent paper by Mailho-Fontana et al. 2020, a new set of specialised dental glands were discovered in Brazilian ringed caecilians (Siphonops annulatus) that may produce venomous enzymes – but further research is needed to confirm this. These enzymes were demonstrated to have gelatinolytic, caseinolytic and fibrinogenolytic properties. This incredible discovery may allow researchers to rethink the evolution of venom in vertebrates (since it could have evolved independently in both amphibians and reptiles) and inspire new studies about caecilian toxinology.

Through histological and biochemical analysis of saliva samples, researchers found A2 phospholipase enzymes which could mean that some fossorial caecilians inject venomous saliva via these dental glands into their earthworm prey in order to incapacitate and digest them. These enzymes are found in many other venomous creatures such as scorpions, snakes and insects. It is also worth noting that many venoms have originated as saliva such as in komodo dragons, shrews, bats and slow lorises making the prospect of venomous gymnophiones very exciting!

Other caecilians including the basal genus Rhinatrema showed similar dental glands to the ringed caecilians which could suggest that caecilians evolved to inject oral venom early on in their evolution (Jared et al. 2020). 

Written by Xavier Mahele

References

Blotto, B.L., Lyra, M.L., Cardoso, M.C., Trefaut Rodrigues, M., R. Dias, I., Marciano‐Jr, E., Dal Vechio, F., Orrico, V.G., Brandão, R.A., Lopes de Assis, C., Lantyer‐Silva, A.S., Rutherford, M.G., Gagliardi‐Urrutia, G., Solé, M., Baldo, D., Nunes, I., Cajade, R., Torres, A., Grant, T., Jungfer, K.‐H., da Silva, H.R., Haddad, C.F. and Faivovich, J. (2020) The phylogeny of the Casque‐headed Treefrogs (Hylidae: Hylinae: Lophyohylini). Cladistics

Brodie, E.D., Feldman, C.R., Hanifin, C.T. et al. (2005) Parallel Arms Races between Garter Snakes and Newts Involving Tetrodotoxin as the Phenotypic Interface of Coevolution. Journal of Chemical Ecology 31, 343–356.

Brodie, E., Nussbaum, R., & Marianne DiGiovanni. (1984) Antipredator Adaptations of Asian Salamanders (Salamandridae). Herpetologica, 40(1), 56-68.

Daly, J. W., Spande, T. F. & Garraffo, H. M. (2005) Alkaloids from Amphibian Skin:  A Tabulation of Over Eight-Hundred Compounds. Journal of Natural Products 68, 1556–1575 

Duellman, W. E. & Trueb, L. (1996) Biology of Amphibians. McGraw-Hill.

Hague, M.T.J., Stokes, A.N., Feldman, C.R., Brodie, E.D., Jr. and Brodie, E.D., III. (2020) The geographic mosaic of arms race coevolution is closely matched to prey population structure. Evolution Letters 4: 317-332.

Heiss, E., Natchev, N., Salaberger, D., Gumpenberger, M., Rabanser, A. and Weisgram, J. (2010), Hurt yourself to hurt your enemy: new insights on the function of the bizarre antipredator mechanism in the salamandrid Pleurodeles waltl. Journal of Zoology 280: 156-162.

Jared, C., Antoniazzi, M.M., Navas, C.A., Katchburian, E., Freymüller, E., Tambourgi, D.V. and Rodrigues, M.T. (2005) Head co‐ossification, phragmosis and defence in the casque‐headed tree frog Corythomantis greeningi. Journal of Zoology 265: 1-8.

Jared C, Mailho-Fontana PL, Antoniazzi MM, Mendes VA, Barbaro KC, Rodrigues MT, Brodie ED (2015) Venomous Frogs Use Heads as Weapons. Current Biology Volume 25, Issue 16,

Jared, C., Mailho-Fontana, P.L., Marques-Porto, R. et al. (2018) Skin gland concentrations adapted to different evolutionary pressures in the head and posterior regions of the caecilian Siphonops annulatus. Scientific Reports 8, 3576.

Mailho-Fontana, P.L., Jared, C., Antoniazzi, M.M. et al. (2019) Variations in tetrodotoxin levels in populations of Taricha granulosa are expressed in the morphology of their cutaneous glands. Scientific Reports 9, 18490.

Mailho-Fontana, P. L. et al. (2020) Morphological Evidence for an Oral Venom System in Caecilian Amphibians. iScience 23, 101234.

Mendes VA, Barbaro KC, Sciani JM, Vassão RC, Pimenta DC, Jared C, Antoniazzi MM. (2016) The cutaneous secretion of the casque-headed tree frog Corythomantis greeningi: Biochemical characterization and some biological effects. Toxicon Volume 122.

Paluh D, Stanley EL, Blackburn DC. (2020) Evolution of hyperossification expands skull diversity in frogs. Proceedings of the National Academy of Sciences 117 (15) 8554-8562.

Savitzky, A.H., Mori, A., Hutchinson, D.A. et al. (2012) Sequestered defensive toxins in tetrapod vertebrates: principles, patterns, and prospects for future studies. Chemoecology 22, 141–158.

Smith, B. P. et al. (2002) Evidence for Biosynthesis of Pseudophrynamine Alkaloids by an Australian Myobatrachid Frog (Pseudophryne) and for Sequestration of Dietary Pumiliotoxins. Journal of Natural Products 65, 439–447.l

 

Filed Under: Croaking Science Tagged With: Amphibians, Croaking Science, sharp ribbed newt, Venomous

TOAD IN THE HOLE!   Froglife’s new Yorkshire T.O.A.D project, leaps forward thanks to a ‘Green Recovery Challenge Fund Award’.

December 14, 2020 by Kathy Wormald

At a time when amphibians are declining at a faster rate than birds and mammals, Froglife’s new Yorkshire T.O.A.D. (Tails of Amphibian Discovery) project is about to launch, with a grant by the ‘Green Recovery Challenge Fund’ – a key player in the Prime Minister’s 10 Point Plan to kick-start nature recovery and tackle climate change. Froglife is one of the first environmental projects awarded a grant from the £80million fund which is being delivered by the National Lottery Heritage Fund in partnership with Natural England and the Environment Agency. The funding, just shy of £250k, (£247,800)  is set to run from now until 31st March 2022 and builds on Froglife’s existing work in Yorkshire –  from the successful Toad Summit they ran in 2020 to their extensive habitat work, in particular a corridor in Sheffield helping birds and dormice as well as amphibians.

Yorkshire T.O.A.D will focus on work around Common Toads, a species that has declined by 68% over 30 years, and if allowed to continue at the same rate, could be extinct within 10. Froglife will address these declines by working with council landowners in Wakefield, Kirklees, Leeds, York and Calderdale on 22 wildlife sites that have been identified either as in need of restoration or will benefit from new habitat creation,  by helping improve freshwater and terrestrial habitats whilst also implementing mitigation strategies at toad patrol sites. They hope to create 32 ponds, restore 22, plant 5 wildflower meadows and install 1 dipping platform and deliver a volunteer training programme on habitat management for a minimum of 660 volunteers.

Froglife have already been co-ordinating ‘Toads on the Roads’ toad patrols up and down the country for over 20 years. Yorkshire T.O.A.D will work with existing toad patrols in Yorkshire, to undertake a toad patrol audit in order to identify further improvements that can be made to stop toad road mortality – the largest contributor to the decline in toad populations. (Toads return to their traditional breeding ponds each year and new and busier roads are hard for them to successfully navigate).

Credit: Peter Wolstenholme

To raise awareness and understanding of the importance of conserving toads and indeed all of the UKs wildlife as well as the vital role that nature plays in combatting the negative impacts of climate change, Yorkshire T.O.A.D will also run a public engagement programme. This will include working with communities to create 5 Neighbourhood Wildlife Corridors through urban landscapes, the hosting of Wildlife Gardening Workshops and Open Days: Pond Doctor Marquees, VR Experience, AR Experience, Wildlife Photography, Walks and Graffiti Boards.

Kathy Wormald, CEO of Froglife said “At other sites where we’ve made habitat improvements, we’ve witnessed an increase in common toad populations so we’re very excited to have received this funding to further are work in Yorkshire, a county in which we already have close working relationships.”

Environment Minister, Rebecca Pow, speaking of Yorkhire T.O.A.D and all of the other projects which have been awarded government funding said:  

“These projects will drive forward work across England to restore and transform our landscapes, boost nature and create green jobs, and will be a vital part of helping us to build back greener from coronavirus. I look forward to working with environmental organisations as these projects help address the twin challenges of biodiversity loss and climate change, while creating and retaining jobs as part of the green recovery.”

 

 

Filed Under: News Tagged With: green recovery challenge fud, National Lottery Heritage Fund, new, Project, T.O.A.D, toads, Toads on Roads, TOADSVR, yorkshire

The Future’s looking ‘Rose-y’

December 9, 2020 by Kathy Wormald

You may know Mya-Rose Craig better as ‘Birdgirl’, as she has been publicly sharing her passion for birds, wildlife and nature for the majority of her 18 years, but what may not be so well documented is her love of amphibians. That is, until now! UK amphibian and reptile conservation charity, Froglife are delighted to announce that Mya-Rose will be joining zoologist and author Jules Howard and wildlife gardener and writer Kate Bradbury, by becoming a Patron.

The youngest person to receive an honorary doctorate in science from the University of Bristol AND the youngest to have seen half of the world’s birds (approximately 5,400), Mya-Rose started her blog ‘Birdgirl UK’ aged just 11. She set up the not-for-profit organisation Black2Nature just a few years later, hosting nature camping excursions into the Somerset Countryside for Visible Minority Ethnic (VME) young people, many from inner cities.

Already engaged in similar immersive activities around social inclusion as those employed by Black2Nature, Froglife provides interaction with nature for those with dementia, learning difficulties, inner city schools and prisons through pond creation, reptile and amphibian identification, the creation of wildlife gardens and other habitats including bird-boxes, and both Mya-Rose and Froglife see their partnership as a natural fit.

“I am hugely excited to become a Patron of Froglife and look forward to us working together to create more opportunities to help encourage children and teenagers from minority ethnic backgrounds connect with the natural world. I have been really interested in frogs and amphibians since I visited the Ecuadorian Amazon age eight years old and saw my first poison dart frogs and the hugely dangerous Fer De Lance snake.” said Mya-Rose.

 

“Mya-Rose’s campaigning and passion for the environment are much to be admired and we know she’ll be an inspiration for all of us at Froglife, as well as all of our supporters.  We know how busy she is and we feel honoured and delighted to have her on board,” said Froglife CEO Kathy Wormald.

 

 

 

 

Filed Under: News Tagged With: BirdgirlUK, Patron, Welcome, Youth

Yorkshire Wildlife Tunnel

December 7, 2020 by admin

After a new housing development near Sowerby Bridge was completed, local naturalists started to report seeing large numbers of toads being killed on the newly built road when migrating to their breeding pond. The large size of the toad population had not been noted during the planning stages for the development so it had not been factored in to the plans.

The council took the matter very seriously and approached the developer to install a wildlife tunnel retrospectively.  The road was closed to traffic while it was dug up and the tunnel was installed.  This will make a massive difference to the toads in the area because they can now pass safely under the road to their breeding pond. A camera has been installed in the tunnel to monitor the usage and to check that the tunnel is working well for toads and other wildlife. This is an excellent result for toads and a demonstration of how we can make a difference for wildlife when developers, the public and the council all work together.

Sign our Wildlife Tunnel Campaign: Give Wildlife the Green Light – Build Wildlife Tunnels to save the Common Toad

Filed Under: News Tagged With: camera, common toad, wildlife tunnel, yorkshire

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