Description
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Typhlonectes compressicauda can reach 523 mm in total length (Taylor 1968). The posterior part of the body is compressed, with a keel (Taylor 1968). 81-86 primary annuli are present but secondary annuli are lacking (Taylor 1968). Dermal scales are present (Wake 1975). The skull is zygokrotaphic (Nussbaum 1983). The head is relatively thick and wide (Taylor 1968). There are four rows of teeth (Taylor 1968), which are curved and have broadly dilated crowns rather than pointed tips (Wilkinson 1991; Hraoui-Bloquet and Exbrayat 1996). The tongue has two large narial plugs (Taylor 1968). Tentacles are located directly behind the nasal orifices (Jared et al. 1999). Narial apertures are subtriangular (Wilkinson 1989). Eyes are covered by thin skin in juveniles and thick, nonglandular skin in adults (Wake 1985). Fritzsch and Wake (1986) showed that ampullary organs are present on the head, most densely on the snout, and presumably used for electroreception; the original paper (Fritzsch and Wake 1986) examined a larval specimen of T. compressicauda, and an adult specimen of what was thought to be T. compressicauda, concluding that this species retained ampullary organs into adulthood, but a later paper (Dünker et al. 2000) refers the adult specimen to the closely related T. natans. (See Comments section below for more on taxonomy.)Larvae look like miniature adults, though they possess lateral lines (Jared et al. 1999) and broad leaf-like gills (Taylor 1968). Gills are attached dorsally and fused at the bases (Wilkinson 1989). Within 24-48 hours after birth, the gills fall off (Exbrayat and Delsol 1985). Ampullary organs are present on the larval head (Fritzsch and Wake 1986) and may be retained into adulthood, since adults of the related species T. natans have ampullary organs (see paragraph above).Described by Duméril and Bibron (1841). Typhlonectes compressicauda has a diploid karyotype of n=28 (Wake et al. 1980). This species has frequently been confused with T. natans in the literature (M. H. Wake, pers. comm.); specimens reported as T. compressicauda in the literature prior to 1994 should be regarded as most likely belonging to T. natans (R. Nussbaum, pers. comm., cited in Smits and Flanagin 1994). More extensive taxonomic review is required (IUCN 2008).
- Delsol, M., Exbrayat, J.-M., Flatin, J., and Gueydan-Baconnier, M. (1986). ''Nutrition embryonnaire chez Typhlonectes compressicaudus (Dúmeril et Bibron, 1841), Amphibien Apode vivipare.'' Mémoires de la Société Zoologique de France, 43, 39-54.
- Delsol, M., Flatin, J., Exbrayat, J.-M., and Bons, J. (1981). ''Développement embryonnaire de Typhlonectes compressicaudus, Amphibien apode vivipare. Hypothéses sur la nutrition embryonnaire et larvaire par un ectotrophoblaste.'' Comptes Rendus de l'Académie des Sciences, Paris, 293, 281-285.
- Delsol, M., Flatin, J., Exbrayat, J.-M., and Bons, J. (1983). ''Développement embryonnaire de Typhlonectes compressicaudus (Duméril et Bibron, 1841). Constitution d'un ectotrophoblaste.'' Bull Soc Zool Fr, 108, 680-681.
- Duméril, A. M. C., and Bibron, G. (1841). Erpétologie Générale ou Histoire Naturelle Complète des Reptiles. Volume 8. Librairie Roret, Paris.
- Dünker, N., Wake, M. H., and Olson, W. M. (2000). ''Embryonic and larval development in the caecilian Ichthyophis kohtaoensis (Amphibia, Gymnophiona): a staging table.'' Journal of Morphology, 243(1), 3-34.
- Exbrayat, J. M. (1986). ''Quelques aspects de la biologie de la reproduction chez Typhlonectes compressicaudus (Duméril et Bibron 1841) Amphibien Apode.'' Bulletin de la Société Herpetologique de France, 38, 20-23.
- Exbrayat, J.-M., and Delsol, M. (1985). ''Reproduction and growth of Typhlonectes compressicaudus - a viviparous gymnophione.'' Copeia, 1985, 950-955.
- Fritzsch, B., and Wake, M. H. (1986). ''The distribution of ampullary organs in Gymnophiona.'' Journal of Herpetology, 20, 90-93.
- Gonçalves, A. A. (1977). ''Dimorfismo sexual de Typhlonectes compressicaudus (Amphibia: Apoda).'' Boletim Fisiological Animale, Universidade de São Paulo, 1, 141-142.
- Gonçalves, A. A., and Sawaya, P. (1978). ''Oxygen uptake by Typhlonectes compressicaudus related to the body weight.'' Comparative Biochemistry and Physiology, 61, 141-143.
- Hornscheid, A., and Greven, H. (1996). ''Activities of the caecilian Typhlonectes compressicauda in the aquarium.'' Salamandra, 32, 181-192.
- Hraoui-Bloquet, S., and Exbrayat, J. M. (1996). ''The teeth of Typhlonectes compressicaudus (Amphibia, Gymnophiona) during the development.'' Annales Des Sciences Naturelles-Zoologie Et Biologie Animale, 17(1), 11-24.
- IUCN (2008). 2008 IUCN Red List of Threatened Species. www.iucnredlist.org. Downloaded on 6 December 2008.
- Moodie, G. E. E. (1978). ''Observations on the life history of the caecilian Typhlonectes compressicaudus (Duméril and Bibron) in the Amazon Basin.'' Canadian Journal of Zoology, 56, 1005-1008.
- Murphy, J. B., Quinn, H., and Campbell, J. A. (1977). ''Observations on the breeding habits of the aquatic caecilian Typhlonectes compressicaudus.'' Copeia, 1977, 66-69.
- Nussbaum, R. A. (1983). ''The evolution of a unique dual jaw-closing mechanism in caecilians (Amphibia: Gymnophiona) and its bearing on caecilian ancestry.'' Journal of Zoology, London, 199, 545-554.
- Renous, S., and Gasc, J.-P. (1986). ''Le fouissage des Gymnophiones (Amphibia): hypothèse morphofonctionelle fondée dur la comparaison avec autres vertébrés apodes.'' Zool. Jahrb., Abt. f. Anat, 114, 95-130.
- Sammouri, R, Renous, S, Exbrayat, J. M., and Lescure, J. (1990). ''Développement embryonnaire de Typhlonectes compressicaudus (Amphibia, Gymnophiona).'' Ann. Sci. Nat. Zool. Paris, 11, 135-162.
- Sawaya, P. (1947). ''Metabolismo respiratório de anfibio Gymnophiona, Typhlonectes compressicauda (Dúmeril et. Bibron).'' Boletim Faculdade de Filosofia, Ciências e Letras, Universidade de São Paulo, Serie Zoologia, 12, 51-56.
- Sprackland, R. G. (1982). ''Typhlonectes compressicaudus (Aquatic Caecilian). Reproduction.'' Herpetological Review, 13, 94.
- Toews, D., and Macintyre, D. (1977). ''Blood respiratory properties of a viviparous amphibian.'' Nature, 266, 464-465.
- Toews, D., and Macintyre, D. (1978). ''Respiration and circulation in apodan amphibians.'' Canadian Journal of Zoology, 56, 998-1004.
- Verdade, V. K., Schiesari, L. C., and Bertoluci, J. A. (2000). ''Diet of juvenile aquatic caecilians, Typhlonectes compressicauda.'' Journal of Herpetology, 34, 291-293.
- Wake, M. H. (1975). ''Another scaled caecilian (Gymnophiona: Typhlonectidae).'' Herpetologica, 31, 134-136.
- Wake, M. H. (1978). ''Comments on the ontogeny of Typhlonectes obesus, particularly its dentition and feeding.'' Papéis Avuls. Zool. São Paulo, 32, 1-13.
- Wake, M. H. (1985). ''The comparative morphology and evolution of the eyes of caecilians (Amphibia, Gymnophiona).'' Zoomorphology, 105, 277-295.
- Wake, M. H. (2006). ''A brief history of research on Gymnophionan reproduction and development.'' Reproductive biology and phylogeny of Gymnophiona. J. M. Exbrayat, eds., Science Publisher Inc., Enfield.
- Wake, M. H., Hafner, J. C., Hafner, M. S., Klosterman, L. L., and Patton, J. L. (1980). ''Karyotype of Typhlonectes compressicauda (Amphibia, Gymnophiona) with comments on chromosome evolution in caecilians.'' Experientia, 36(2), 171-172.
- Wilkinson, M. (1989). ''On the status of Nectocaecilia fasciata Taylor, with a discussion of the phylogeny of the Typhlonectidae (Amphibia: Gymnophiona).'' Herpetologica, 45, 23-36.
- Wilkinson, M. (1991). ''Adult tooth crown morphology in the Typhlonectidae (Amphibia: Gymnophiona): a reinterpretation of variation and its significance.'' Zeitschrift für Zoologische Systematische und Evolutionsforschung, 29, 304-311.
Distribution and Habitat
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This species occurs in Colombia, Venezuela, and Peru, Brazil, French Guiana, Guyana, and possibly in Bolivia and Suriname, at elevations of 0-200 meters above sea level (IUCN 2008). Typhlonectes compressicauda is aquatic, living in small, submersed holes within the muddy banks of small river tributaries (Toews and Macintyre 1977), in swamp savannas (Exbrayat and Delsol 1985).
Life History, Abundance, Activity, and Special Behaviors
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Typhlonectes compressicauda live in small aquatic mud burrows in the banks of river tributaries, near the air-water boundary (Toews and Macintyre 1977). Observations of captive animals indicate that they can stay immersed in water up to 100 minutes at 24°C (Hornscheid and Greven 1996). Juvenile T. compressicauda have been observed actively foraging in shallow water at night (Verdade et al. 2000). When they do move, it is accomplished by lateral undulations (Renous and Gasc 1986).Both lungs are developed in the genus Typhlonectes, in contrast to most other Gymnophiona, and a "tracheal" lung is also present (Wilkinson 1989; Smits and Flanagan 1994). Typhlonectes compressicauda also has a higher hemoglobin concentration than most other amphibians (Toews and Macintyre 1978). Given its habitat, it may frequently encounter both hypoxic and hypercarbic conditions (Toews and Macintyre 1977). Lungs provide the majority of respiration in this species (Sawaya 1947), but during immersion more than half of the oxygen uptake may be cutaneous (Gonçalves and Sawaya 1978). Carbon dioxide release is accomplished primarily by transcutaneous means in T. compressicauda (Sawaya 1947). Breeding occurs in the rainy season, which extends from about December/January to July/August (Exbrayat and Delsol 1985). Males are sexually mature at about the age of three years, and thereafter breed annually, while females breed biennially (Exbrayat 1986). Copulation in captivity has been reported to last up to three hours (Murphy et al. 1977; Sprackland 1982). Fertilization is internal, as is the case for all caecilians (Gower and Wilkinson 2002; Wake 2006). This species is viviparous with gestation lasting about 6 months, after which 2-4 larvae are born (Delsol et al. 1981; Delsol et al. 1983). Young are born at the beginning of the dry season, when water levels are still high (Exbrayat and Delsol 1985).During gestation, embryos depend initially on yolk for nourishment. After the yolk supply has been depleted, the fetuses consume uterine wall secretions (Delsol et al. 1986), degenerating unfertilized oocytes (Delsol et al. 1986; Exbrayat 1986), and dead sibling embryos (Delsol et al. 1986; Exbrayat 1986).This species forages actively at night in shallow water, both at the bottom and at the surface (Verdade et al. 2000; Wake 1978). Juvenile T. compressicauda consume aquatic oligochaete worms, aquatic insects and larvae (especially surface-dwelling culicid larvae), and terrestrial insects in the wild, as well as occasional frog tadpoles and frog eggs (Verdade et al. 2000). In addition, decomposing plant matter is frequently found in juvenile caecilian stomach contents, though it is not clear whether this represents accidental ingestion or deliberate detritivory (Verdade et al. 2000). Adults eat dead fish (Exbrayat and Delsol 1985), aquatic arthropods such as shrimp (Moodie 1978), coleopteran pupae (Wake 1978) and pieces of aquatic plants (Exbrayat and Delsol 1985). Ampullary organs in the head of T. compressicauda are thought to function in the detection of weak electrical signals from live prey as well as predators (Fritzsch and Wake 1986; Jared et al. 1999).
Life History, Abundance, Activity, and Special Behaviors
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Typhlonectes compressicauda appears to be common and occurs in many protected areas (IUCN 2008).
Relation to Humans
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This species approaches permanent fishing nets in search of dead fish to eat, and may be captured by bringing the nets in (Exbrayat and Delsol 1985). Typhlonectes compressicauda has also been collected by digging animals out of riverbank burrows (Toews and Macintyre 1977). Juveniles have been collected foraging at night among vegetation at river margins (Verdade et al. 2000).
Lifespan, longevity, and ageing
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Maximum longevity: 4.9 years (captivity)
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Typhlonectes compressicauda
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Typhlonectes compressicauda, the Cayenne caecilian, is a species of amphibian in the family Typhlonectidae that lives in water. It is found in Amazonian Brazil, Peru, and Colombia as well as in Guyana and French Guiana, and likely Suriname,[2] and according to some sources, Venezuela.[1] It is an aquatic caecilian that inhabits permanent rivers and marshes mainly in the lowland forest zone.[1]
Description
The Cayenne caecilian is an elongated, dark grey, black or steely blue amphibian with no limbs. The body is flattened laterally and has a number of transverse folds, giving it a segmented appearance. A long fin runs along its back, and it grows to a length of 30 to 55 cm (12 to 22 in). It has a more highly derived morphology than some more primitive species, showing differences in lung structure, the reproductive organs, and the kidneys.[3]
Distribution
The Cayenne caecilian occurs in South America, including the Amazon basin and river systems in the Guianas. It is found at altitudes of up to 200 m (660 ft) above sea level. Because it is common and has a wide range, it is listed as of "Least Concern" in the IUCN Red List of Threatened Species.[1]
Biology
The Cayenne caecilian lives in shallow streams and rivers. It spends the day in a communal burrow, emerging at night to hunt through the sediment for small invertebrates, such as insect larvae and shrimps. It also eats small fish. It has no functional eyes and probably detects its prey by touch or by the vibrations made when the prey moves. It has slime glands all over its body and secretes copious amounts of noxious mucous if attacked. Nevertheless, it is eaten by birds, snakes, and large fish.
At breeding time, a male and female Cayenne caecilian twine around each other and the male places a spermatophore in the female's cloaca. Fertilisation is internal and the Cayenne caecilian is ovoviviparous. Six to 14 young hatch inside the female's oviduct with gills. At first, they feed on the yolks of their eggs, but they develop rasping teeth and later consume glandular secretions produced by the lining of the oviduct. Birth takes place after about eight months and the juvenile caecilians shed their temporary teeth and develop their adult dentition.
The Cayenne caecilian is considered to have several characteristics that are more highly derived than other more primitive species. Its karyotype has been compared with that of other caecilians, and its diploid number has been found to be 28, a fact that does not support the hypothesis that, during the period of amphibian evolution, the number of chromosomes became reduced. However, many caecilians have not yet been karyotyped and the exact evolutionary relationships between the species have not yet been determined, so the hypothesis is not necessarily incorrect.[3]
References
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Typhlonectes compressicauda: Brief Summary
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Typhlonectes compressicauda, the Cayenne caecilian, is a species of amphibian in the family Typhlonectidae that lives in water. It is found in Amazonian Brazil, Peru, and Colombia as well as in Guyana and French Guiana, and likely Suriname, and according to some sources, Venezuela. It is an aquatic caecilian that inhabits permanent rivers and marshes mainly in the lowland forest zone.
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