CLASSIFICATION OF ICHTHYOPHIS
PHYLUM :- CHORDATA (Notochord, dorsal tubular nerve cord present and gill slits present )
Group :- CRANIATA ( Definite head. Cranium with brain present )
Sub-phylum :- VERTEBRATA ( vertebral column present)
Division :- GNATHOSTOMATA ( Jaws and paired appendages present )
Super class :- TETRAPODA ( Paired limbs, lungs, bony skeleton and cornified skin)
Class :- AMPHIBIA ( Scaleless glandular skin , have 3 chambered heart , cold blooded, 2 occipital condyles, can live in water and land both )
Order :-GYMNOPHIONA (Vermiform Amphibia without limbs or limb girdles).
Genus :- Ichthyophis
Ichthyophis is distributed in tropical regions and found in Sri Lanka, Philippines, Borneo, Java, Scychelles, Mexico to Argentina and India (Mysore) and is the only representative of Gymnophiona living today in tropical countries.
HABIT AND HABITAT
Ichthyophis lives in burrows and leads a fussorial life in moist ground. The animal is blind and adapted for burrowing life. It feeds on invertebrates.
GENERAL CHARACTERSTICS OF ICHTHYOPHIS
- Commonly called as caecilian.
- Animal is wonn-like and slender, measuring about 30 cm in length. Body divided into head, trunk and tail.
- Body is covered with a smooth, slimy and transversely ringed skin consisting of small calcified scales arranged in transverse rows. Squirt glands in skin discharge an irritating fluid.
- Head contains eyes, nostrils and a pair of sensory tentacles. Tympanic membrane, tympanic cavity and columella absent.
- Eyes small, functionless and covered by skin. Though reduced but contain all the parts. A small protrusible tentacle is present between eye and nostril.
- Skull compact, roofed with bone.
- Limbs and limb girdles absent. Vertebrae amphicoelous.
- Laryngotracheal chamber is prolonged into a distinct trachea. Right lung elongated, while left lung is reduced. Anus is sub-terminal.
- Males are provided with eversible copulatory organ, which shows advanced characters. Fertilization internal. Male’s cloaca is everted like copulatory organ. Eggs are laid in moist burrows. Mother coils around eggs till they hatch into tadpoles.
Ichthyophis resembles Amphibia in having a 3- chambered heart, conus arteriosus, urinogenital organs and brain like Amphibia. But it differs from living Amphibia in having scales in dermis and meroblastic eggs. The animal also shows parental care, as the females take care of the eggs by keeping
them in the coils of the body, till they hatch. It shows combination of primitive and advanced characters. The fonner characters include dennal scales in the skin and number of dennal bones in the skull. Loss of limbs, short post-anal part and copulatory organs are specialized characters.
The animal is limbless, contains calcified Scales and vestigeal tail and above features, hence it is Ichthyophis.
- Book of Practical Zoology VERTEBRATE by S.S.LAL – Rastogi Publications.
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