01/09/2019

General Features of Reptiles and Classification up to order, Types of snake venom, Symptoms of snake bite and First aid treatment


General Characters of Reptiles and Classification up to order

Class Reptiles include about 8000 to 8200 living species found all over the world. It includes snakes and lizards.  The animals from class reptile are placed in 4 orders as given in the table below:


Sr. No.
Order
Examples
1
Rhynchocephalia
Sphenodon (Living fossil)
2
Squamata
Lizards ( wall lizard (Gecko), flying lizard (flying dragon), Varanus,  Chameleon, etc.

Snakes (Cobra, King cobra, Krait, Viper (Pit viper, Pitless viper) Rat snake, Python etc.
3
Chelonia
Turtles, Tortoises, Terrapins, Tryonix, Green turtle,  etc.
4
Crocodilia
Crocodiles, Alligators, Caimans, Gharials

General Features  of Reptiles
1.     Reptiles are terrestrial or aquatic.
2.     They are carnivorous, some are herbivorous.
3.     They  are the cold blooded animal (Ectothermic or heliothermic Gk. Helios= sun).
4.     Skin is dry and without any gland except femoral gland in male lizzards.
5.     Skin is covered with dry scales, spines, scutes or plates.
6.     Tetrapod and pentaductile.
7.     In lower reptile heart is incomplete four chambered and in higher reptile (Crocodile) complete
        four chambered.
8.     Respiration by lungs.
9.     Presence of cloaca.
10.   Vertebrae are procelus.
11.    RBCs are nucleated.
12.    Presence of 12 pair of cranial nerve.
13.   They are generally oviparous, some are ovi-viviparous.
14.    Fertilization is internal.
x. Chameleon, gecko, cobra, turtle, snakes,  crocodile, etc. 


Order — Rhynchocephalia (Gk., Rhynchos = a beak/snout; Kephale = a head).  
 General characters:
1.       It is lizard like animal measures about 60 cm. long.
2.      This animal remain unchanged since evolved about 200 million year hence called living fossil. .
3.       It is medium sized reptile also called as tuatara.
4.       It found only on few island surrounding New Zealand.
5.       The colour of body is olive  green or brown in colour  with white or yellow spots.
6.       Body covered with scales.
7.       Presence of mid-dorsal crest of spine.
8.       Spines are absent on neck.
9.       Horn of scale present on head. 
10.   Snout is beak like.
11.   Limbs are pentadactyle.
12.   Sphenodon has third eye present on top of the head between eyes.
13.   Presence of two rows of teeth in bucal cavity.
14.   It is nocturnal  animal and burrowing in habitat.
15.   Hibernate (Winter Sleep) during winter.
16.   It is carnivorous.
17.   Female lay dozen of eggs in to the dig burrow.
 Order — Chelonia (Gk. Chelone = a tortoise):
General characters: 
1.      Body more or less  is elliptical and dorso-ventrally flattened.
2.      limbs are weak and pentaductile. In some marine forms limbs are modified into paddles.
3.      Dorsally body is covered with plates, plastron or  polygonal scutes or leathery skin.
4.      Neck, limbs and tails are retractile.
5.      Tail is very short.
6.      In adults teeth are absent and are replaced by horny plates.
7.      Copulatory organ in male attached to ventral wall of colaca.
8.     These are oviparous animals.
9.      Regular hibernation occurs in temperate region.
10.   In the skull, quadrate bone is immovably articulated. 
11    Cold blooded animal
11.  Ribs and thoracic vertebrae are usually fused with carapace.
12.  Pelvic girdle consists of ilium, ischium and pubis.
13.  Pectoral girdle composed of scapula, pro-coracoid and coracoid bones.
14  Oviparous animal  
15.  Fertilization is  internal  
16  Eggs are laid into dug in sand.
17 Presence of 12 pair of cranial nerves. 

Ex. Green turtle, Testudo, indian soft shell turtle etc.
 Order — Squamata (Latin, sqamatus = scaly):
 1. They are cold blooded animals
2. They are terestrial burrowing and arborial in habit.
3. They lives under the rock or beneath the stone, or burrow of other animals.
4. They are carnivorus, insectivorus.
5. Body is covered with dry skin.
6. Presence of Scale on body.
7. Body is divisible into head, neck, trunk and tail.
8. Tail is long.
9. Presence of nectitating memberane.
10. Eye lids are movable and in organism they are immovable (Snakes).
11. Tongue is protrucible, long, sticky, bifid in some animals (Snake)
12. Hibernation is occure.
13. Exretary product is uric acid.
14. Limbs are pentaductile. in some organism limbs are absent (Snake)
15 RBC are ovel, nucleted.
16. Herat is of incomplete 4 chambers.
17. Vertebrae are pro-coelus
18. Fertilization is internal
19. Oviparous (Lizard, gecko, Chamelion)  or ovi-viviparous (Viper)
20. Eeggs laid on ground, cracks, or burrow of other animals. king cobra build the nest.
 Ex. Lizard, Wall lizard , varanus


Order — Crocodilia/Loricata (Latin: Crocodilus = a crocodile; Loricatus = clad in nail): 
Ex. Crocodile
 General characters:
    1.     Crocodiles are sem-aquatic predator found in feshwater, salt water etc.
    2.       They are carnivorous.
    3.       They  cold blooded.
    4.       Respiration by Lung
    5.       Presence of power full limb with jaws.
    6.       Eyes and nostril are positioned on top of the head.
    7.       Tail is massive and muscular.
    8.       Dorsal side of body is covered with protective plates.
    9.       Four chambered heart.
    10.     Fertilization is internal.
    11..    Presence of 12 pair of cranial nerve
    12     Oviparous animal.
    13     Female lays eggs on ground  in nest near water out of vegetation and 
              mud.
    14.    In adults extensive parental care about young.
 

Types of Snake, Snake Venom and First Aid treatment

 

The actual poison of venom appears to consist of albuminous substances in solution. It has different actions in different snakes. Venom may (i) act on nerve cells and cause respiratory paralysis; (ii) destroy the endothelium of smaller blood vessels and allow blood to seep into the tissues; (iii) destroy erythrocytes and (iv) cause blood coagulation.

1. Neurotoxic Venom:

1.      Neurotoxic venom found in cobras, krait, sea snakes, etc.

2.      It causes paralysis of the respiratory muscles.

3.      Death of victim caused due to respiratory paralysis.

4.      Venom primarily affects the nervous system,

5.      Venom of Kraits is also neurotoxic.

2. Haemotoxic Venom:

1.      It is found chiefly in vipers.

2.      It causes haemorrhage.

3.      The haemolysis and haemorrhage caused by the venom.

4.      so pronounced that bleeding occurs from the eyes, renal and alimentary tract epithelium.

5.      Chance of survival from snake bite depends to a great degree on the amount of venom


Venomous and Non-venomous snake  snake


Non-Poisonous Or  Non- venomous Snakes:

1. Python:

1.      Python is a large, massive, non-poisonous snake covered with small scales and shields on the head and large plates below.

2.      Tail is prehensile.

3.      It has a vertical pupil.

4.      It constricts warm-blooded animals in its coils and kills them due to suffocation,

5.      Pythons have vestigial pelvic girdles

6.      The claws are seen on either side of the cloaca, they play a part in copulation.

7.      They are oviparous.

8.      Indian python, is over 8 metres long.

9.      It is grayish-brown with red and black spots and a mark like a spearhead between the eyes, ventral side is yellowish.

10.  Scales of upper lip have pits.

11.  It is nocturnal and very often waits on trees for its prey.

12.  It loves to lie in water.

13.  Pythons are found in Asia and Africa.

3. Eryx: Sand Boa (Mandul)

1.      Eryx johnii is commonly called Indian or John Sand Boa or Mandul .

2.      It is found in dry, hot, sandy parts of India, Africa and Sri Lanka.

3.      The body is short and flat with a stumpy tail, eyes are minute.

4.      The head is pointed and resembles the tail, hence, it is often called a two-head boa.

5.      It has a uniformly sandy brown colour,

6.      it may have cross bars and dark spots, with small smooth scales above

7.      Eryx is 1 metre long. It is a harmless, sub-terranean snake.

8.      It lives in burrows of small rodents on which it feeds

9.      It also feeds on lizards and worms.

4. Zamenis (Ptyas): Rat Snake

1.      Zamenis mucosus is commonly called dhaman or rat- snake of India.

2.      It is a highly active non-poisonous snake which feeds on rats, small rodents, and frogs.

3.      It grows to a length of 2.5 metres, and has an elongated tail.

4.      Scales above are smooth with pits, below they are large transverse bands. Colour is brownish above with black bands on the tail.

5.      It is pale yellow ventrally.

6.      The eyes are large with round pupil.

7.      It is very swift, ill-tempered and bites viciously.

8.      It is oviparous.

9.      It is regarded as a friend of the farmers because it destroys rats.

10.   It is found in India, Myanmar and Java.

Poisonous or Venomous Snakes:

The poisonous snakes are kraits, cobras, pitless vipers and pit vipers, sea snakes, etc. These possess poison glands and fangs.

Following poisonous snakes are found in India 

1. Bungarus: Krait (Manyar)

2. Naja: Cobra

4. Viper:

3. King cobra   (Nagraj)

5. Hydrophis: Sea snake

 

1. Bungarus: Krait (Manyar)

1.      Bungarus is commonly called krait.

2.      It has several species in India and Malaya.

3.      It is slender and about 1 metre long, of pale brown colour with darker bluish-black markings having white cross bars, ventral surface is white.

4.      Fangs are small.

5.      Scales are smooth.

6.      The backbone is ridged having a central row of enlarged hexagonal  scales.

7.      It is oviparous and the female incubates the eggs.

8.      It feeds on toads, mice and smaller snakes.

9.      The common krait, Bungarus caeruleus, comes into homes, is slow moving, but is highly poisonous.

10.  Its venom is more poisonous than that of a cobra.

2. Naja: Cobra

1.      Naja is commonly called Indian Cobra or nag.

2.      Naja naja is also called Naja tripudians.

3.      It is a highly poisonous snake growing up to 2 metres in length, of brown or blackish colour.

4.      It lives in holes and under stones.

5.      It feeds on frogs, lizards, rats and other snakes.

6.      Scales are smooth, dorsal surface of the head has small scales and large shields.

7.      Presence of hood is characteristics of  cobra.

8.      hood spread is more than in other cobras.

9.      Pupil is round.

10.  Fangs are small and non-movable.

11.  On each side is a large poison gland enclosed in a fibrous capsule, its duct runs into a canal in the fang.

Venom is neurotoxic

3. King cobra  -

1.      Naja hannah (king cobra also called Hamadryad), is found in India, Malaya, and southern China.

2.      It grows up to 6 metres, but has a diameter of only 7.5 cm, the average length is 3.5 metres.

3.      It is the world’s largest poisonous snake and the most deadly and venomous of all snakes. 

4.      The venom injected is large in quantity and causes quick death due to respiratory paralysis.

5.      The king cobra has a small head, the hood spread is only about 10 cm, on the hood are transverse bands and white marks.

4. Viper:

1.      Vipera (viper) head is large, flat, and covered with small scales.

2.      Nostrils are lateral, eyes are far forwards and there is a sensory pit between the eye and the nostril in some.

3.      Pits are sensory organs with which the snake can detect its prey. The scales on the body are keeled. Tail is short and tapers abruptly.

4.      Scales on the head are small and keeled.

5.      In vipers,  movable fangs with canals.

6.      The fangs are erected for biting and folded back against the roof of the mouth when not in use.

5. Hydrophis: Sea snake

1.      Hydrophis is commonly called Sea snake.

2.      The body is long and laterally compressed posteriorly.

3.      Head and neck are very slender.

4.      The general colour is dark olive green above with yellowish cross bars and white below. The ventral scales are small.

5.      Tail is laterally compressed and acts like paddle in swimming.

6.      Eyes are small with rounded pupil.

7.      Viviparous. Carnivorous, feeding on fishes, etc. Hydrophis is deadly poisonous.

8.      its venom is neurotoxic.

Symptoms of snake bite

Signs or symptoms of a snake bite may vary depending on the type of snake, but may include:

1.      Puncture marks at the wound

2.      Redness, swelling, bruising, bleeding, or blistering around the bite

3.      Severe pain and tenderness at the site of the bite

4.      Nausea, vomiting, or diarrhea

5.      Labored breathing (in extreme cases, breathing may stop altogether)

6.      Rapid heart rate, weak pulse, low blood pressure

7.      Disturbed vision

8.      Metallic, mint, or rubber taste in the mouth

9.      Increased salivation and sweating

10.  Numbness or tingling around face and/or limbs

11.  Muscle twitching

 First Aid treatment; Definition 

First aid is emergency care given immediately to an injured person. The purpose of first aid is to minimize injury and future disability. In serious cases, first aid may be necessary to keep the victim alive.

 

The first aid  treatment for snake bite 

·         Treat all bites as poisonous

·         Keep person calm and as still as possible

·         Remove all jewelry

·         Wash wound with soap & water

·         Apply suction device if person is more than an hour from treatment

·         Immobilize limb below the heart

·         Give 100% oxygen if available.

·         Apply tourniquet, ice, or water.

·         Take a photograph of the snake from a safe distance if possible. Identifying the snake can help with treatment of the snakebite.

·         Keep calm.

·         .


Venomous and non venomous snake Distinguishing Characters 


Near about 2500 to 3000 species of snake found all over the world. But not all the species of snake are poisonous.  Because of few of them, entire snake world have bad reputation. 
According to WHO in India about 45000  to 50000 victims die due to snake bite every year. But official record is only about  12000 to 15000. 
About 350  species of snake are poisonous. In India 216 species of snake are found and about 52 specis are poisonous . 
Many snakes are similar in appearance and colour patterns. So, there is need of clear cut identification of poisonous and non-poisonous snake. Majority of snakes are non-poisonous and harmless. The non-poisnous snakes are python, rat snake, trinket snake, freshwater snake, etc. the common poisonous snakes found in India are cobra, king cobra, Indian viper, russel’s viper, krait, coral snake, sea snake,


Identification of poisonous and non-poisonous snake is not hard task. 

Following key will serve to distinguish poisonous and non-poisonous snake.
1.    Identification of snake by the nature of bite mark
2.    Identification of snake by flow of blood from wound
3.    Identification of snake by nature of tail.
4.    Identification of snake by nature head shield or scales.
5.    Identification of snake by vertabrial
6.    Identification of snake by ventral scales.

1.    Identification of snake by the nature of bite mark:

If non-poisnous snake bites tends to several small punctures in two rows due to maxillary teeth mark and palatine teeth mark.
But if poisonous snake bite it shows two prominent spots due to fang , along with a palatine teeth mark.
  
 2.    Identification of snake by the flow of blood from the wound
When non-poisonous snake bites, blood flows from the wound for short period and gets clots naturally but if poisonous snake bites, blood-coloured fluid continuously oozes through the wound because venom prevents the clotting of blood.

3.    Identification of snake by nature of tail.
If the tail is flattened and laterally compressed then the snake is a sea snake and deadly poisonous. 
If we observed the tail is rounded and cylindrical, it is a land snake. Then, snakes may be poisonous or non-poisonous. 

4. Identification of snake by nature the nature of ventral scales. 
If ventral scales are broader and extending fully acros the belly. Snake may be poisonous or non-poisonous . 
 
If the ventral scales are large transverse plates extending fully across the ventral side of the belly, the snake may be poisonous or non-poisonous. Now examine the dorsal scales of the head

5.  Identification of snake by nature head shield or scales.
If the dorsal side of head is covered with shields. The snake may be poisonous or non-poisonous.
Head shield: 
If 3rd supra-labial shield touches to the nostril and eye then the snake is poisonous.  The snake may be a cobra, king cobra or coral snake.



 But if the 3rd supra labial shield is not touched to the nostril and eye then the snake is non-poisonous and the snake may be a rat snake.
If the snake has small scales and a large shield on the head but does not have the characteristics of the cobra, or rat snake then examines the ventral side of the head. If 4th infralabial shield extends fully from the ventral side of head. Then it is a poisonous snake and the snake may be krait.

Scales on head 
If the head is covered with a smaller scale, then the snake is a viper and it is a poisonous snake.
If the head is covered with smaller scales and there is lorea pit.  it is pit viper and snake is poisonous.

 

6.  Identification of snake by nature of vertebral.
if the mid-dorsal side shows the presence of hexagonal scales called vertebral the snake is poisonous and it is krait. In addition to vertebral scales, the krait can be identified by examining the 4th infra-labial shield and a single row of sub-caudal.


 

 



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