Amphibia-Arboreal Forms

Previous: Burrowing Form

A number of animals are adapted to Arborial habitats and are called tree frog eg. some species of Rana,Rhacophorus,Hyla etc.They belong to different families. They have certain modifications for clinging on trees and climbing purpose.
1)They have adhesive or sucking disc at end of digits.
2)They develop opposable toes.
3)Their eggs develop mostly inside large eggs.


THE END.

Habitat and Adaptation in Amphibia cont'd- Burrowing Forms

Burrowing Forms:

They are found mostly in order Apoda and some other amphibians (Anurans).Apodans are highly specialized for burrowing habit and have following features:

1)Vermiform bodies.
2)Compact bony roofed skull.
3)Absence of limbs.
4)Presence of reduced eyes usually hidden in skin.
5)Presence of some special structure to dig burrow.
6)Dull colored skin.

Next:Arboreal Forms

Habitat and Adaptation in Amphibia continued - Amphibious forms

Amphibious Forms


These are certain amphibians which can live on land and water with same expertise eg.some animals have swimming mode of locomotion in water and jumping habit on land.They use their hind limb for swimming in place of tail fin as in case of aquatic amphibians. Aquatic adaptations found in these Anurans are as follows-
1)Compact boat shaped body.
2)Highly developed powerful muscles in hind limbs for effective swimming strokes.
3)Webbed hind limb digits.
4)Cutaneous respiration.


Next:Burrowing Forms

Habitat and adaptation in Amphibia Page 6- Aquatic Forms

They are found to inhabit water bodies and adopt swimming mode of locomotion.They have certain modifications for swimming purpose as well as aquatic habitat.
1)Eel type body construction.
2)Presence of gills for respiration.
3)Development of fins.
4)Presence of weak limbs.
5)Lidless eyes.
Eg.Salamander,Proteus etc


Continued on Page 7 - Amphibious Forms

Habitat and Adaptation in Amphibia continued Page 5-Terrestrial Forms

Terrestrial forms

They are toads and frogs. They are less dependent on water for their survival. They require water only during breeding season. For locomotion they have jumping habit and in order to avoid enemies they have small and stout body.For locomotion they have certain modifications as-
1)Elongation of hindlimb and loss of tail.
2)Development of powerful muscles.
3)Shortening of vertebral column with very little mobility to avoid jerk during jumping.
4)Attachment of pelvic girdle to vertebral column is shifted quite forward.
Eg. Rana,Bufo etc.


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Habitat and Adaptations in Amphibia continued Page 4

They have not been to leave water completely. Modern amphibian forms are reported to inhabit many possible habitat as aquatic, burrowing, arborial and other possible habitats. In these forms modification or adaptation take place according to habitat. These habitats are listed below along with modification found in these amphibians:
Terrestrial forms
Aquatic firms
Amphibious forms
Burrowing forms
Arborial forms

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Adaptation and Habits of Amphibia (Page 3)

Page 3
Amphibians are mainly aquatic but they live on land and fresh water also.They are usually confined to neighborhood of slowly moving fresh water or stagnant water.This is particularly true for great majority of species where eggs are laid in water.But there are numerous exceptions in which either the development of young ones take without water or parents carry eggs on their bodies during development. Such forms are confined to land only and called terrestrial forms.Apart from this habit,breeding habit ,protective habit which are peculiar in these amphibians.


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Page 2-Biology,Amphibians cont'nd

Page2 (amphibians cont'nd)

Limbless Amphibians

Limbless amphibians are included in order Apoda and sometimes called as blind worms also(eyes poorly or less developed)
They mostly inhabit tropical and subtropical regions of Americas,Africa and Asia excluding Medagasca.They do not have fossil forms.
Habitat-
1)They are burrowing forms except few strictly aquatic forms.They burrow in moist ground with their strong heads.
2)They are long body worm like burrowing animals and resemble large earthworms.
3)Limbs and girdles abscent.
4)In many genera in grooves a series of small calcified scales are found unlike other amphibians. Due to linear arrangement of these scales in transverse grooves false segmentation appears in their body.
5)Eyes small functionless and covered by skin.
6)Mouth terminal.
7)They are carnivorous in food habit feeding upon small animals which are found on ground.
8)Tail either absent or very small just like Anurans.
9)Anus or Vent present at posterior end of body at ventral surface.
10)There is a characteristic sensory protrusable tentacle present on side of face between nostril and eyes in all species. It arises from a special groove in maxilla and called as facial tentacle. It compensates for sensory organ. It is protruded by being descended with blood like eractile organ and retracted by strong muscles.

11)Tympanic cavity and tympanic membrane absent. Columella also absent.
12)Kidney extends whole length of coelom.
13)Liver posteriorly constricted into many numbers of lobes.
14)Laryngotracheal chamber is prolonged into distinct trachae supported by cartilage.
 Tracheal lungs are found in these animals just like snails.Left lung is rudimentary (because body is not narrow, therefore cannot accommodate)
15)Comus arteriosus is without spiral valve.There are only 2 pairs of aortic arches i.e. systemic arch and pulmonary arch.
16)Unlike 4 branchial clefts in embryonic life of Apoda.
17)Fertilization is internal with the help of enlarged,eversible cloacal valve which serves as copulatory organ.It is armed with hooks.

Copulatory organ

18)Skull differs considerably from modern amphibians and reveals resemblances with extinct labrynthodontia i.e. limbless amphibians are primitive and retain some primitive characters mentioned below:
1.Skull solid,compact on dorsal side and have large number of bones than modern amphibian skull.
2.Cranium covered by dermal bones.
3.A pair of post orbital and post frontal bones are present.
4.Frontal and parietal are not fused and separate unlike modern amphibians.
5.Orbit is small and surrounded by bones.
6.Hyoid apparatus and dentary primitive.
7.Vertebral column also differs in many respect from modern amphibians such as
1.Number of vertebrae numerous i.e. 200 to 300 and centrum is me amphicoelus.
2.Notochord persists.
3.First vertebra devoid of odontoid process.
4.Ribs bifurcated.

20.These are either oviparous, ovoviviparous and sometimes viviparous.In oviparous forms female guards eggs in burrows after egg laying until larvae hatch out.


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Our Frog family Amphibia

Amphibia are cold blooded animals.

Poikelotherms- cold blooded
Home other swarm blooded.

It may be defined as a class of those animals which are cold blooded vertebrates amphibious in habit having tetrapodous limbs or pentadactyle pattern and require presence of water for breathing purpose.Amphibia have got an intermediate position between fishes and reptiles. They resemble in general pattern of their body with fishes and to some extent in anatomical pattern of body they are more reptilian. In development they are fish like and exhibit many important fish characters in larval forms.They possess some important characters which are mentioned below-
1)In animal kingdom amphibians are placed between fish and reptiles. They include frogs,toads,salamanders, Gymnophions(Apoda-order limbless amphibians or Ceacelians).They are amphibious in habit i. e. they may live on land as well as in water.They have 2 pairs of pentadactyle limbs.

2)They are cold blooded animals. Their skin is smooth or rough,moist, glandular and naked without any scales except in Gymnophiona.

3)Eyes with movable eyelids.

4)Nostrils paired and connected to mouth cavity.

5)Skull with occipital condyles to articulate with atlas.

6)Teeth present.

7)Heart 3 chambered,RBCs nucleated and oval.

8)Respiration by gills,lungs,skin and by buccal cavity.

9)Aotic arches symmetrical.

10)Kidney mesonephric provided with permanent nephrostoma.

11)Cloaca present which receives duct from reproductive system, excretory system and opening of digestive system.

12)Brain with 10 pairs of cranial nerves.

13)Eggs with gelatinous covering usually laid in water.

14)Larva pass through aquatic stage before metamorphosis.

15)They reveal some parental care.


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