Taxonomic experiments on amphibians and reptiles

Summary

Source of content: general zoology lab guide.

Operation method

Taxonomic experiments on amphibians and reptiles

Principle

1. to understand the characteristics of the order and important families; 2. to recognize common and economically valuable species; 3. to learn how to use a search form for taxonomic identification.

Materials and Instruments

Specimens
Magnifying glass, dissecting mirror, dissecting needle, tweezers, dissecting tray, straightedge, caliper.

Move

I. External morphology and measurements of amphibians

1. anuran amphibians
Body length: from the end of the muzzle to the posterior end of the body;
Head length: from the end of the muzzle to the posterior margin of the jaw joints;
Head width: distance between right and left jaw joints;
Snout length: from the end of the snout to the anterior corner of the eye;
Nasal spacing: distance between right and left nostrils;
Eye spacing: narrowest distance between the inner margins of the right and left upper eyelids;
Upper eyelid width: widest point of the upper eyelid;
Ocular diameter: longitudinal distance of the eye;
Tympanic width: maximum diameter;
Forearm hand length: from behind the elbow to the end of the third finger;
Hindlimb full length: from posterior body center to end of fourth toe;
Tibial length: distance between the two ends of the tibia;
Foot length: from the proximal end of the inner metatarsal process to the end of the fourth toe;
2. Tailed amphibians
Body length: from the end of the muzzle to the end of the tail;
Head length: from the end of the muzzle to the nuchal fold;



Head width: straight line distance between right and left nuchal folds (or at the posterior width of the head);
Snout length: from the end of the snout to the anterior corner of the eye;
Eye diameter: length of eye diameter parallel to body axis;
Tail length: from the posterior margin of the anus to the end of the tail;
Tail height: distance from the highest point of the tail.
II. Classification of Amphibia

The amphibians surviving nowadays can be divided into 3 orders: Caudata, Anuraceae and Amphipoda.
1. domestic search of the families of the order Caudata
2. Domestic search for each family of anurans
III. Classification of Reptilia

The reptiles surviving nowadays can be categorized into Beaked Cephalopods, Turtles, Squamates and Crocodilians. Beakheads are only found in New Zealand, and the rest of the reptiles are searched as follows:
1. Tortoises (Chelonia or Testudoformes) common family search in our country
Squamata: This order is divided into suborders of lizards and snakes, and the main differences are listed in the table below:



2. suborder Lacertilia (Lizards) common family search in China



3. common families of the suborder Serpentes in China
4. Alligator (Grocodiliai): body covered with large firm armor; large body size; strong and powerful tail; male with a single mating organ.
Alligator sinensis: muzzle bluntly rounded; fourth mandibular tooth embedded in a depression in the upper jaw. Skin with horny square scales. Forelimbs 5-fingered, hindlimbs 4-toed.

Caveat

1. Most of the dipped and peeled specimens used in the experiment have changed their original color, and in order to enable students to recognize the true form of the animals, the relevant videos and slides can be shown.

Common Problems

I. Assignment

1. Summarize the taxonomic features of each order of amphibians and reptiles and master one or two of the identifying features.

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