A complete collection of frogs

Frogs belong to amphibians of the family Anura. Adults are tailless, eggs are laid in water, fertilized in vitro, hatched into tadpoles, breathe through gills, after variation, adults mainly breathe with lungs, and breathe with skin. Taking insects and other invertebrates as staple food, almost all of them are experts at killing forest and farmland pests. Let's take a look at the data of frogs.

The living environment of frogs

Frogs are variable temperature animals with bare skin, which can not effectively prevent the evaporation of water in the body. They can not live without water or humid environment all their life. They are afraid of drought and cold. Most of them live in tropical and temperate rainy areas, and there are very few species distributed in cold zones. They can only live in water when they are young, and can live on land when they grow up. The respiratory organs of frogs are lungs and skin, and the respiratory organs of larval tadpoles are gills.

The tongue structure of frogs

The frog's tongue root is at the front of the mouth, the tip of the tongue is inward, and there is mucus on the tongue to catch insects. It blinks when swallowing food, and the eyes and faces are closed from the bottom up. Frogs are omnivorous animals, of which plant food accounts for only about 7% of the diet, and animal food accounts for about 93% of the diet. The main foods are rice leaf roll, rice borer, rice bract insect, armyworm, corn borer, cotton red bollworm, gray borer, eyebrow mosquito night moth, rice eye butterfly, rice negative mud worm, rice weevil, beetle, ladybug, white-backed planthopper, gray-backed planthopper, rice black bug, brown-backed planthopper, rice leafminer, duckweed, fruit fly, mosquito and so on.

Reproduction and development of frog

Frogs are dioecious, fertilized in vitro, sperm and eggs are fertilized in water, the fertilized eggs hatch into tadpoles, the newly hatched tadpoles have a flat and long tail, breathe with the Gill on both sides of the head, grow the tadpoles in the inner gills, look like a fish, grow the baby with limbs, breathe with lungs, the skin is exposed, assist breathing, the baby gradually develops into a frog, and the development process is fertilized egg → tadpole → young frog → adult frog.

The visual nerve of frog

The nerve cells in the retina of frog eyes are divided into five types, one only responds to color, the other four only responds to a certain feature of the moving object, and can transmit the decomposed characteristic signal to the visual center of the brain-the optic tectum. There are four layers of nerve cells in the optic tectum. The first layer responds to the contrast of the moving target, the second layer can extract the convex edges of the target, and the third layer can only see the surrounding edges of the target. The fourth layer is only concerned with the light and shade change of the dark leading edge of the target. These four layers of features are like drawings drawn on four sheets of transparent paper, stacked together to form a complete image. As a result, among the fast-moving small animals of all shapes, the frog can immediately identify its favorite flies and moths, while not responding to other flying things or motionless scenery.

Morphological characteristics of frog

1. Head: the head of the frog is flat, slightly triangular, the snout is slightly pointed, the mouth is broad, transverse fissure, and is composed of the upper and lower jaws, the dorsal front of the maxilla has an external nostril, the outer edge of the external nostril has a nasal flap, and the eyes are large and protruding, born on the left and right sides of the head, with upper and lower eyelids, the inner side of the lower eyelid has a semi-transparent nictitating membrane. At the back of the mouth corner of the male frog, there is a light brown membrane fold as a vocal sac, which bulges into a bubble when singing.

2. Trunk: behind the tympanic membrane of the frog, the trunk is short and wide. There is a small hole on the dorsal side of the trunk between the two legs of the trunk, which is the cloacal hole.

3. Limbs: the forelimb of the frog is short, composed of five parts: upper arm, forearm, wrist, palm and finger. 4 fingers are unwebbed. In the reproductive season, there is an inflated protuberance on the inside of the first finger of the male frog, which is called marriage tumor. The hind legs of frogs are long and developed, which are divided into five parts: thigh, tibia, tarsal, metatarsus and toe, 5 toes, webbed between toes, and a hard keratinized distance on the inside of the first toe.