Animal Diversity: Chordata

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Table 3: Classification of Apoda up to families Family Character Eocaecilia Rhinotrematidae Small (up to 30 cm) Terrestrial with aquatic larvae Ichthyophidae Moderately large (up to 50 cm) Terrestrial with aquatic larvae Uraeotyphlidae Small terrestrial, oviparous forms with possibly direct development Scoleocomorphidae Moderately large terrestrial forms, possibly viviparous Caeciliidae Very small (10 cm) to very large (1.5 cm) terrestrial and aquatic forms, oviparous and viviparous species, no aquatic larval stage Typhlonectidae Small to large (75 cm) aquatic and semi-aquatic forms, viviparous with aquatic larvae b. ORDER 2. URODELA (CAUDATA). Distribution Example Fossil from Early Jurassic of N. America 9 Species in S. America Eocaecilia Epicrionops, Rhinatrema 36 Species in Asia Caudacaecilia, Ichthyophis 4 Species in India Uraeotyphlus 5 Species in Africa Crotaphatrema, Scoleocomorphus ~ 90 Species in Central and S. America, Africa, India and the Seychelles Islands 13 Species in S. America Boulengerula, Brasilotyphlus, Caecilia, Dermophis, Gegeneophis, Geotrypetes, Gymnopis Typhlonectes, Atretochoana, Chthonerpeton, Nectocaecilia, Potomotyphlus These include the salamanders and newts, the latter being small, semi-aquatic forms. Urodeles are found in temperate and subtropical climates in the Northern Hemisphere but do not reach the tropics in the New World. The elongated body consists of head, trunk, and a well developed tail, the latter being retained throughout life. Two pairs of limbs occur in most species. Larvae resemble adults except for the presence of gills, and like adults, have teeth in both the upper and lower jaws. The urodeles have a greater tendency to show generalized characters of the class amphibia, in comparison to the much more specialized Anura. The group shows different types of forms, varying from the terrestrial salamanders, such as Salamandra maculosa, which is viviparous, to the fully aquatic forms, such as Necturus. Furthermore, there is a tendency to retain larval characters in the adults of certain aquatic forms, the process known as paedomorphosis / neoteny. Examples include Megalobatrachus, which has no eyelids but loses its gills in the adult; In Cryptobranchus, the spiracle remains open being used for expulsion of water during 8
espiration. Amphiuma is an elongated form with very small legs, no eyelids and four branchial arches. An extreme example of neotenous forms is Necturus, which has external gills but has such a reduced lung that the animal can live as a permanently aquatic form. Similarly, Siren shows all larval characters and has no hind limbs. The terrestrial newts are of different types: some are definitely terrestrial like Triturus vulgaris, although it is not able to live in very dry habitats. The limbs support the body weight, their soles being applied to the ground and turned forwards. The tail shows reduction to form a rod-like organ but when the animal returns to the water for breeding purposes, the tail develops a large fin. On the other hand, is the genus Ambystoma, which has eleven species, in which some races become mature without metamorphosis, because of lack of iodine in water, whereas others are genetically neotenous. The important families of urodeles include: Table 4: Classification of Urodela up to families Family Character Distribution Example Species Karaurus Fossil from Jurassic of Kazakhstan Sirenidae Small (15 cm) to large (75 cm) elongate aquatic forms, with external gills, pelvic girdles and hind-limbs absent Cryptobranchidae Very large (1 m) to huge (> 1.5 m) aquatic forms, paedomorphic with external fertilization of the eggs Hynobiidae Small to medium size (30 cm) aquatic or terrestrial forms, external fertilization of eggs, aquatic larvae Amphiumidae Very large (1m) elongate, aquatic forms, lacking gills Plethodontidae Tiny (3 cm) to large (30 cm) aquatic or terrestrial forms, direct development or some with aquatic forms 9 4 Species in N. America 1 Species in N. America and 2 Species in Asia Karaurus sharovi Siren, Habrosaurus, Pseudobranchus Cryptobranchus, Megalobatrachus ~ 36 Species in Asia Batrachuperus, Hynobius, Onychodactylus, Pachynynobius, Ranodon, 3 Species in N. America ~ 265 Species in N., C. and S. America, 1 Species in Europe Salamendrella Amphiuma Gyrinophilus, Eurycea, Pseudotriton, Manculus
Page 1 and 2: List Of Contents I. Introduction An
Page 3 and 4: Tetrapoda The class Amphibia is com
Page 5 and 6: II. CLASSIFICATION Basal tetrapods
Page 7: Microsaurs represent a diverse grou
Page 11 and 12: latter living on land have a warty
Page 13 and 14: Family Character BRACHYCEPHALIDAE V
Page 15 and 16: Family Character Rhacophoridae Very
Page 17 and 18: mineralized tissue in their mesoder
Page 19 and 20: available led to an extensive remod
Page 21 and 22: Devonian. This is particularly mark
Page 23 and 24: The median fin is completely lost a
Page 25 and 26: special development for water absor
Page 28 and 29: Respiratory movements involve the a
Page 30 and 31: heart they are separated by a peric
Page 32 and 33: capillaries. The ventral branch cal
Page 34 and 35: Skull of frog (Figure 12) 1. Skull
Page 36 and 37: Typical second vertebra 1. In frog
Page 38 and 39: 10. The sternum lies in the mid-ven
Page 40 and 41: Hind-limbs bones of frog (Figure 17
Page 42 and 43: diencephalon with the medulla oblon
Page 44 and 45: tympanic membrane or tympanum. The
Page 46 and 47: kidney with peritoneal connections
Page 48 and 49: desert-dwelling frogs like Cycloran
Page 50 and 51: the ova as they pass down the ovidu
Page 52 and 53: C. Eggs carried by the parents- I.
Page 54: 4. Walter, H.E. and Sayles, L.P. Bi

Animal Diversity: Chordata

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