Earthworms, how snakes walk, how earthworms crawl

Meandering and crawling. The difference is that earthworms are slow, while snakes crawl fast!

All I know about the earthworm is that it has a lot of fine bristles, and it uses the bristles to sense things around it, and it uses this to walk.

Snake: A snake is a reptile with a long cylindrical body with no limbs and scales all over its body with many ribs. The snake has no legs, but it can walk, and it crawls with the help of the flexion of its body and the scales under its belly.

The end of the snake's ribs is movable, and the scales on the ventral surface are flattened and arranged like roof tiles. When the snake crawls, the tip of the ribs, against the scales of the ventral surface, nails the ground and supports the body. The front section is nailed, and the back section moves forward; The back section is nailed, and the front section moves forward.

The ribs of the whole body and the scales underneath moved in turn, and the snake wriggled and slid away. However, snakes do not easily crawl on slippery ground.

The snake walks on its belly.

The muscles in the abdomen push backwards.

Earthworms walk by telescoping.

The tail retracts and sticks out at the head.

Earthworms crawl through the body wriggling, earthworms belong to the phylum Annelids, the main feature of this phylum is that the body is composed of many segments, earthworms except for the front and last few segments, the rest of the segments have bristles, the body wall of the earthworm is muscular, divided into ring muscle and longitudinal muscle.

Earthworms rely on the alternating contraction of the ring muscle and the longitudinal muscle and the coordination with the bristles on the body surface to move. When the earthworm advances, the bristles on the back of the body are nailed into the soil, so that the back part cannot move, and the ring muscle contracts and the longitudinal muscle relaxes, and the body stretches forward.

Then the bristles on the front of the body are nailed into the soil so that the front part cannot move, and then the longitudinal muscles contract, the ring muscles relax, and the body shortens forward. In this way, the earthworm stretched and shrank and moved forward.

The movement of earthworms relies on the interaction and contraction of the longitudinal and annular muscles and the cooperation of the bristles on the body surface.

When the earthworm advances, the bristles at the back of the body are not moving, then the ring muscle contracts, the longitudinal muscle relaxes, and the body stretches forward, and then the bristles at the front of the body are nailed into the soil and does not move, then the longitudinal muscle contraction, the ring muscle relaxes, and the body shortens forward and advances. The inner end of the bristles has bristle follicles, traction muscles, and traction muscles, and due to the alternating expansion and contraction of the traction muscles on the bristle follicles, the bristles can stretch out or retract into the body wall.

For example, when the longitudinal muscles of the 4 segments at the front end of the earthworm are contracted, the earthworm here becomes shorter and thicker, the bristles stretch out, insert into the ground, support and fix the worm body at the place, and pull the 5th and 8th segments of the earthworm body to the front; When the anterior 4 longitudinal muscles are dilated and the annular muscles are contracted, the vermiform becomes elongated, and the bristles retract into the body wall and leave the ground, so that the anterior 4 segments stretch forward. By analogy, earthworms can produce wavy wriggling.

Test Method1. Equipment:

coarse paper; flat glass;

2. Main operation steps:

Bounded by the middle line of the horizontal axis, one side is covered with a glass plate, and one side is covered with rough paper;

Place 10 earthworms on both sides, 5 on each side;

Observe after 5 minutes.

3. Experimental results:

Earthworms move through the expansion and contraction of body muscles and the coordination of bristles, on glass with water, bristles can not fix and support the body, on rough paper, bristles can fix and support the body Therefore, earthworms move faster on rough paper than on glass plates.

Earthworms move in a creeping contraction.

The mode of movement is peristaltic contraction. Several somites form a group, one group of medial longitudinal muscles contract, the ring muscles relax, and the somites shorten, while pressure in the body cavity increases, and bristles stick out to attach. In the adjacent somite group, the annular muscle contractions, the longitudinal muscle relaxes, the somites lengthen, the pressure in the body cavity decreases, and the bristles are retracted.

Each somite group alternately contracts the longitudinal and annular muscles with the adjacent somite group, causing the body to move forward in waves. The earthworm can advance 2-3 cm with each contraction, and the direction of contraction can be reversed, so it can do backward movements.

Catch an earthworm, take a needle, and try it yourself.