Yummy mummies, caecilians on the EDGE, and the gigantic Minhocão: 'The Secret World of Naked Snakes', part II

More thoughts on the ZSL meeting 'The Secret World of Naked Snakes', held on Monday 7th December. In the previous article I discussed Mark Wilkinson and David Gower's presentations [for relevance of pic used above, read on].

Alexander Kupfer was up next, and provided an excellent overview of reproductive diversity, viviparity and parental care in caecilians (his talk was titled 'Yummy mummy: skin feeding and caecilian reproductive biology') [images above, from Wilkinson et al. (2008), show mother Siphonops annulatus looking after, and feeding, babies]. Caecilians exhibit five different reproductive modes, which is good for a group that only contains 180 species (anurans exhibit over 40 different reproductive modes, but remember that (as of this month) there are over 5830 anuran species). Maternal investment in huge in caecilians: some oviparous species lay their eggs over a period of three days and produce eggs that can be 10 mm wide (almost as wide as the mother's body). In viviparous species, embryogenesis is completed in the oviducts and the foetuses then feed on secretions from the oviduct lining. In at least some species, the juveniles also imbibe some sort of cloacal secretion that the mother releases (Wilkinson et al. 2008).

The discovery of maternal provisioning of altricial juveniles by way of dermatophagy (the eating of the mother's skin by the babies: Kupfer et al. (2006)) is now quite well known thanks to media coverage and its appearance in the Attenborough TV series Life in Cold Blood (again I must register my dislike of that title). Perhaps less well known is that Kupfer and others have suggested that dermatophagy might be widespread in the group: it's been documented in the African caeciliid Boulengerula taitana and the distantly related South American caeciliid Siphonops annulatus, yet specialised juvenile dentitions (of the sort linked to skin-feeding in Boulengerula and Siphonops) are seen in other caeciliid taxa as well, like Geotrypetes from Africa. In fact, the dermatophagic specialisations seen in caeciliids are almost certainly homologous across the clade, meaning that this form of maternal care may well have been around since the Cretaceous (as this is when the lineages including Boulengerula and Siphonops are thought to have diverged) (Wilkinson et al. 2008). Matrotrophy (the ingestion of oviduct lining practised by the unborn babies of viviparous caecilians) may well represent a modified form of dermatophagy, as the babies of the viviparous species seem to have inherited their hook-like little teeth from those of ancestral dermatophagic, oviparous species (Kupfer et al. 2006, Wilkinson et al. 2008). Sorry if any of this text seems repetitive: I've previous discussed caecilian dermatophagy at some length here [the Siphonops species S. paulensis shown here. Photo by Ariovaldo Giaretta, from wikipedia].

While it's also become well known that male caecilians have complex and unusual eversible sexual organs (the male caecilian sexual organ is termed the phallodeum) (Gower & Wilkinson 2002), research on female genital anatomy has (as usual) lagged well behind. Very little is known, but Kupfer showed slides featuring in-progress work on female genital anatomy. The female caecilian cloaca looks... complex and weird.

Caecilians on the EDGE, Tet Zoo on stage

The final talk of the meeting was Helen Meredith's overview of caecilian conservation biology, focusing in particular on her role as project co-ordinator for EDGE amphibians. You should, by now, know what EDGE means, and what it's all about: if not, please go here on Tet Zoo, or visit the EDGE site. The antiquity, bizarre biology, and low diversity of caecilians ('low diversity' as compared to other extant amphibians: caecilians comprise about 3% of extant amphibian diversity) means that they are - or, at least, should be - high profile in terms of conservation efforts. In fact, ALL top 10 'potential EDGE amphibians' are caecilians! [for more on image used below, read on...].

Unfortunately, the dearth of knowledge I referred to earlier means that we know worryingly little about the conservation status of the 180 known caecilian species. Something like 66% of all caecilian species are 'data deficient' when it comes to information on conservation status: contrast that with the 0.6% of birds in the same category. Helen's lament: "What have birds got that caecilians haven't?". Actually, as Helen explained, raising the public's awareness of caecilians and the conservation issues they face is not particularly easy. They look worm-like, they're obscure, and the bits of their biology that make them fascinating - matrotrophy in particular - "Makes it hard to warm to caecilians, especially if you're a woman".

Efforts to help conserve the highly endangered Sagalla caecilian Boulengerula neideni from the Taita Hills Complex of the Eastern Arc Mountains in Kenya - the first conservation effort focusing on the protection of a caecilian species - involved habitat restoration, reserve creation, and 'caecilian awareness' projects among local school-kids [Sagalla caecilian shown here. Image © John Measey, from the EDGE blog]. One problem was that the local name for this animal - M'gnori - meant simply 'worm', so a competition was held to come up with a new one. The name that won - Kilima-mrota, chosen by school-girl Shali Kiugha - sounds nice, but is arguably disappointing: it means something like 'animal that moves through the ground and goes thin and dies when left out in the sun'. You can read about the conservation efforts surrounding the Sagalla caecilian here on the EDGE blog.

Faced with the task of promoting a seminar on caecilians, how do you drum up interest? Here were some of the highlights of the meeting, and I say this for purely egotistical reasons, as you'll see. Helen searched far and wide to see what sort of presence caecilians have on the web. Most sites that use the name caecilian are not about zoology at all, but concern all kinds of other crap, for shame. Web pages promoting the ZSL event were sometimes accompanied by hilarious comments that Helen flagged up on her slides. The Londonist's promotional article on the meeting includes the choice comment "I'm repulsed, yet really tempted to go" (sadly, the commenter in question failed to identify themselves in the audience and hence didn't attend after all). The Londonist article is titled 'Ken Livingstone and the Naked Snakes', a line that inspired the comment "Great band - I got all their singles in the 70s back when Ken was barely known" [see image above].

Best of all, however, was Helen's discussion of Tet Zoo's promotion of the event. Wow, my own blog up there in lights (though, note: not the first time Tet Zoo has been mentioned during an academic conference). Regular commenters will be pleased to hear that Helen was quite interested in the discussion we had about 'politicians with extra-curricular interests', and choice quotes from Retrieverman, Chris Taylor, Don Cox, Dartian, Neil Phillips and others all appeared on a slide during her talk [see pic above].

I'm also very pleased to note that at least a few people attended the meeting after seeing it advertised on Tet Zoo. It was nice to meet you, and thanks for saying hello.

The Minhocão: an unappreciated promotional tool for caecilian science (yeah, right)

We attended a fantastic meal after the meeting, and eventually pressed on to the pub. I regaled the assembled with tales of the incredible Minhocão: a gigantic, black, worm-like creature from Brazil and Uruguay that makes tunnels in the ground and also frequents rivers and pools, possesses two horns, and pulls horses, cattle and other livestock to their doom. It's said to have a pig-like snout and under-slung mouth [artistic reconstruction here from wikipedia. By 'Kryptid']. This alleged animal is not a new invention that post-dates Tremors or Dune; rather, it was first reported by Auguste de Saint Hilaire in 1847, and was reportedly seen in additional incidents dating from the 1840s and 1870s. Suggested by some to be a lungfish or (even more stupidly) a living glyptodont, the Minhocão was argued by Karl Shuker to be a gigantic, as-yet-undiscovered semi-aquatic caecilian (Shuker 1995, pp. 147-148). I agree with Karl that the accounts certainly describe a creature that sounds quite caecilian-like (the 'horns' could correspond to the sensory tentacles), but some pretty serious exaggeration must have occurred given that the beast was apparently observed up-rooting trees and grabbing cows, plus it's reported to be about a metre wide and 25 m long!

Funnily enough, the proposed caecilian identity for the Minhocão is not all that well known to caecilian researchers. Needless to say, the reality of the creature might be doubtful, alas [all four speakers shown below. From left to right: Mark Wilkinson, Alexander Kupfer, David Gower, Helen Meredith].

Anyway... well done to the organisers: I enjoyed 'The Secret World of Naked Snakes' a great deal, and I'm sure it did a great job in promoting interest and concern about these remarkable, poorly known animals. Clearly, there is much about caecilians to learn, and meetings such as this one will surely inspire more zoologists to become interested in them. Abstracts of all the presentations given at the meeting can be downloaded from here on the ZSL site.

For previous Tet Zoo articles on caecilians please see...

• Surreal caecilians part I: tentacles and protrusible eyes
• Surreal caecilians part II: pass mum's skin, hold the mayo
• 'The Secret World of Naked Snakes': a ZSL event
• Carnivorous, worm-like amphibians invade London: 'The Secret World of Naked Snakes', part I

Refs - -

Gower, D. J. & Wilkinson, M. 2002. Phallus morphology in caecilians (Amphibia, Gymnophiona) and its systematic utility. Bulletin of the Natural History Museum, London (Zoology) 68, 143-154.

Kupfer, A., Müller, H., Antoniazi, M. M., Jared, C., Greven, H., Nussbaum, R. A. & Wilkinson, M. 2006. Parental investment by skin feeding in a caecilian amphibian. Nature 440, 926-929.

Shuker, K. P. N. 1995. In Search of Prehistoric Survivors. Blandford, London.

Wilkinson, M., Kupfer, A., Marques-Porto, R., Jeffkins, H., Antoniazzi, M. A. & Jared, C. 2008. One hundred million years of skin feeding? Extended parental care in a Neotropical caecilian (Amphibia: Gymnophiona). Proceedings of the Royal Society B 4, 358-361.