Practical Biology The frog Lab. -8-

The frogs are consider from the amphibians in order Anura (meaning tail-less) living on land and in water.

General morphology for frog:*

1- The hind limb longer than forelimb.

2- Absence of neck and tail

3- Up and down movement of the floor of the buccal cavity (a respiratory movement).

4- The external nares or nostrils, which two small openings lying near the anterior tip of the head.

5- The eyes are bulging, which are surrounded by two eyelids and nictitating membrane.

6- The tympanic membrane or ear-drum, which is a more or less circular area found posterior to each eye.

7- Frogs have a long, sticky tongue which they use to capture food.

8- Maxillary teeth: teeth found on the maxillary bone or upper jaw.

9- Vomerine teeth: two knob-like, located on the upper jaw of the frog.( (The vomarine and maxillary teeth are used for holding the prey).

10- frog's external structures also include the webbed feet and the cloaca opening.

* Frog's skin is soft, smooth and loose. It is always kept moist and slimy by mucus secreted by cutaneous glands. therefore, frog's skin serves as an important accessory respiratory organ. Being slimy, it also helps the frog in slipping out of the grip of an enemy.

*Dissection the frog

* Dissection is a fine process which requires certain instruments:

1- Scalpels

2- Scissors: two, a fine pointed pair for dissecting delicate tissues, and another strong pair for cutting bones.

3- Two forceps: one pair pointed, the other blunt.

4- Pins and small nails.

*Note: keep the dissecting instruments in special case and clean after every dissection.

* Anesthesia methods in frogs:

There are three methods using for anesthesia in frog:

1- The knocking: it is knocking a frog is by holding it by it is hind-limbs and striking it violently against edge of table.

2- The pithing: it is mean paralyzes of animal completely by separate spinal cord about central nervous system or brain by using the dissecting needle.


3- The anaesthetizing: by putting the animal in a small tin with a piece of cotton wool rinsed in chloroform or ether.

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