Cooper's black caecilian
(Praslinia cooperi)
Very little is known about Cooper’s black caecilian. This species reaches a total length of 230 mm and is limbless with very small eyes. It is similar in appearance to an earthworm and is only found in a range of 20 km sq. (an area a third the size of Manhattan Island), spending most of its life in underground burrows. It is not common, and nothing is known of its population trend in the wild. The main threat is habitat degradation, due to fire and invasive species. It may also be inherently at risk because of its small range, rendering it vulnerable to factors such as ecological disasters and climate change.
Urgent Conservation Actions
Long-term monitoring of this species; sustainable development of ecologically friendly tourism should be encouraged.
The islands of Mahé and Silhouette in the Seychelles.
Cooper’s black caecilian is one of seven species found in the Seychelles.
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Evolutionary Distinctiveness
Order: Gymnophiona
Family: Caeciliidae
The modern caecilians, with their limbless, superficially worm-like or snake-like bodies, are perhaps the most unusual amphibians in appearance, and their behaviour can be equally strange. The order Gymnophiona (the caecilians) is thought to have diverged from other amphibian lineages about 370 million years ago in the Devonian period, over 150 million years before the first mammal. The earliest caecilian is sometimes reported to be known from the early Jurassic period in Arizona, U.S.A. 190 million years ago and was named Eocaecilia micropodia because it had very small legs and feet. It also had well-developed eyes, suggesting that it was not an entirely subterranean species and may have had more in common with salamanders than with the modern caecilians that became its descendents, and its status as a caecilian is in some doubt. Eocaecilia and Gymnophiona have long independent histories, and it is also thought that they may represent separate lineages that developed similar closed-roof skull morphology convergently, i.e. the same trait arose twice in different parts of the amphibian tree of life, which means that species possessing identical traits are not always closely related (e.g. both bats and birds have wings, but flight evolved independently in these two lineages). This means that the morphology of Eocaecilia may not be the best model for the ancestral caecilian.

Modern caecilians certainly evolved from limbed ancestors however, and therefore underwent major changes in their evolutionary history as they developed elongated, externally-segmented bodies and much-reduced eyes, and lost their limbs, limb girdles and, in the case of the most recently evolved species, their tails. The only currently known fossils of ‘true’ caecilians are three records of isolated vertebrae (back bones) from the Late Cretaceous period (about 100-93 million years ago) of Sudan in Africa, and the Palaeocene (65-53 million years ago) of Brazil and Bolivia. Two older fossils from the Cretaceous of Morocco and the Jurassic of North America are not ‘true’ caecilians, but have been argued to be more closely related to caecilians than any other amphibians. The oldest of these two possible members of the caecilian ‘stem’ lineage is Eocaecilia macropodia. Its small fore- and hind-limbs are thought to have been retained from the last common ancestor of the caecilians and the frogs+salamanders lineage.

Carl Linnaeus (the founder of modern taxonomy) described the first species of caecilian (Caecilia tentaculata) in 1758 and initially thought they were related to snakes. The taxonomic order name “Gymnophiona” is actually derived from the Greek words gymnos (meaning naked) and ophis (meaning snake). The caecilians where therefore originally refered to as “naked snakes” because they lack external scales covering their entire body and the first scientific efforts to classify them could not conceive that they were instead closely related to frogs and salamanders. Many caecilians do actually have scales, but these are small, more fish-like than snake-like, and hidden in folds in the skin, although the Sagalla caecilian and its close relatives (in the Boulengerula genus) have no scales.

The family Caeciliidae (the “common caecilians”) are thought to have branched off from the rest of the amphibian tree over 160 million years ago in the upper Jurrasic period when dinosaurs were still abundant in the earth’s terrestrial ecosystems. Pralinia (commonly referred to as “Cooper’s caecilians”) is a monotypic genus of caecilians found only in the Seychelles, which means the genus is represented by just a single species, Cooper’s black caecilian. The Cooper’s caecilian lineage diverged from all other amphibians an estimate 50 million years ago, making this species as separated in time from their closest relative as chincillas are from procupines. Although there are six other caecilian species in the Seychelles (categorised into two genera within the common caecilians), Cooper’s black caecilian is not very closely related to any of them. This species’ closest relatives are in the Gegeneophis genus, also known as the “forest caecilians”, which are exclusively found in India. The geogrpahical distance of the Indian forest caecilains from their close relative in the Seychelles provides further evidence of how the Indian subcontinental land mass became separated from the Seychelles over the course of an estimated 75 million years of continental drift.
Cooper’s black caecilian is worm-like in appearance, with an elongated, limbless body that reaches a total length of around 230 mm. Both the body and head a flattened, with a width of 9-11 mm. The snout projects slightly beyond the mouth and the eye is clear, rather small, and distinct, in a socket through which a tentacle also emerges. The tentacles are retractable, short and globular, and emerge either side of the head from an aperture about 1.4 mm below the eye. The body appears finely segmented, as a series of grooves divide the body cross-ways into narrow sections or annuli. The colour of this species is a nearly uniform brown, although the first description of the species states its colour as blackish-brown, which explains the common name Cooper’s black caecilian.
Very little is known about this species because its underground burrowing lifestyle renders observation difficult. It probably breeds in streams and pools where the eggs hatch into larvae and develop in water, but this is not confirmed.

Adult Cooper’s black caecilian lives underground, burrowing through the soil using its strong, bony head to compact soil and produce a burrow. They move through the soil by body undulation, and search for their prey, possibly by collecting chemical and tactile signals through its nasal cavity and tentacles. In addition to their sense of smell through their nose, these retractable tentacle sensors either side of their head near to their nostrils may also function to transmit chemical and tactile messages from the environment to the nasal cavity, which aids the caecilian in finding prey.

All caecilians are thought to have internal fertilisation, in that the eggs are fertilised by the male’s sperm inside the female and not when they are being laid. Virtually nothing is known of caecilian mate recognition or courtship, although some aquatic species have been observed performing an undulating dance before mating. During mating, the male everts and inserts his phallus into the cloaca (or reproductive opening) of the female for up to several hours. Caecilians can produce clutches of two to more than 100 eggs.

Coopers black caecilians require damp soil to maintain their moist skin, and to provide a suitable habitat for their prey and good conditions for burrowing.
The Seychelles has a total land area of around 455 km sq., divided between 92 small islands of varying size. Many of the larger islands are the granitic higher peaks of an underwater mountain range called the Mascarene Ridge, although the majority of the smaller islands consist of flat coral atolls. The four largest islands are Mahé, Praslin, La Digue and Silhouette, and the highest point in the Seychelles is Morne Seychellois locate on Mahé, which has an altitude of 905 metres above sea level. The Seychelles endemic caecilian species are only found on the granite islands.

Cooper’s black caecilian lives in relatively undisturbed sites, which are usually forested and above 280 metres above sea level. It burrows in damp soil and leaf litter, and is not recorded from near urban areas or houses.
This species occurs in the granitic Seychelles Islands of Mahé and Silhouette. On Mahé and Silhouette, it has only been found at altitudes above 280 metres above sea level and usually higher in areas that are relatively undisturbed. It is known from only ten localities. The area of occupancy is estimated to be less than 20 km sq.. An old record for Praslin might be erroneous.
Population Estimate
Cooper’s black caecilian is not a common species and it is rarely found.
Population Trend
There is no information about the population trend of this species.
Cooper’s black caecilian is listed as Vulnerable in the IUCN Red List of Threatened Species because its area of occupancy is less than 20 km sq..
The main threat is habitat degradation, mainly due to fire and invasive species. It may also be inherently at risk because of its small range, rendering it vulnerable to factors such as ecological disasters and climate change. Domestic chickens and free-ranging pigs have also been observed feeding on caecilians.
Conservation Underway
Part of the range of this species on Mahé occurs within the 30.5 km2 Morne Seychellois National Park, whilst its Silhouette distribution falls partly in the site of a conservation project that has been established on the island by the Nature Protection Trust of the Seychelles (an NGO with coordinates conservation work on Silhouette) via their Islands Development Company Silhouette Conservation Project. In addition, many small reserves on the islands have been set up by the Seychelles Government and independent agencies to protect specific species and general habitat areas.

The challenges facing conservation projects are very different on the islands of Mahé and Silhouette, the former being a much larger island (148 km2) with a population of 70,000 and number land use conflicts, and the latter being small (just 20 km2) with a population of only 150 people. Silhouette appears to support healthy populations of all four species of Seychelles frog with no immediate threats. However, future hotel and infrastructure development might be a potential threat to these species. In contrast, significant tracts of potentially suitable habitat in Mahé’s central and southern mountains lack any protection against encroaching development, and the distribution and status of Cooper’s black caecilian in these areas is completely unknown.

Conservation Proposed
The long-term monitoring of Cooper’s black caecilian is a vital priority to ensure its conservation in the wild, allowing for any population declines to be quickly detected and investigated. Further research should be conducted into the life history of this species and also the threat processes impacting it Mahé’s central and southern mountains. A Conservation Action Plan should be developed to address the conservation of Cooper’s black caecilian in this region. The development of Mahé and Silhouette for the tourism industry and local population increase is a significant threat to the Seychelles’ biodiversity, including its native amphibians. Wherever possible, sustainable development of ecologically friendly tourism should be encouraged. The Seychelles is marketed as a tourist destination on the basis of its natural beauty, so strategic development of eco-tourism could be immensely beneficial to the conservation of the Seychelles’ endemic amphibians.
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Nussbaum, R.A. 1984. Amphibians of the Seychelles. In: D.R. Stoddart (ed.), Biogeography and Ecology in the Seychelles Islands, pp. 379-415. Dr. W. Junk Publishers, The Hague.

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Roelants, K., Gower, D. J., Wilkinson, M., Loader, S. P., Biju, S. D., Guillaume, K., Moiau, L. and Bossuyt, F. 2007. Global patterns of diversification in the history of modern amphibians. Proceedings of the National Academy of Sciences 104: 887-892.

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