What are the main differences between arthropods and molluscs

Arthropod. Features:

The body consists of a series of segments;

2. The whole body is covered with a layer of chitin.

exoskeleton; 3. Most of the body segments have paired segmented appendages;

4. The body cavity is the blood cavity, and the circulatory organ, the dorsal blood vessel, is located on the back of the digestive tract, with the large artery opening in the head cavity, and the blood circulation is opened;

5. Central nervous system.

Consists of a series of paired ganglia, with the brain located on the dorsal surface of the internal digestive tract of the head and the ventral nerve cord located on the ventral surface of the digestive tract.

Mollusca. Characteristics: The morphological structure of mollusks varies greatly, but the basic structure is the same.

The body is soft and has a hard shell in which the body is hidden for protection, and they are quite slow to move due to the fact that the hard shell hinders movement. It is not segmented, it can be divided into three parts: head, foot, and visceral mass, and the outer membrane often secretes shells. The foot is shaped like an axe and has two shells.

Arthropods are a large group of the kingdom Broadfauna, including spiders, scorpions, crustaceans, and insects. Their main features are the following:

Body segmentation: The body of arthropods is usually made up of multiple links, each with distinct gaps between them, allowing their bodies to move and twist flexibly.

exoskeleton: Arthropods often have a hard exoskeleton covering their body surface, which is made up of keratin, which provides protection and support.

Foot structure: Arthropods' feet are usually connected by multiple segments, each controlled by muscles and syndicated nerves, allowing them to perform complex locomotions and walks.

Diverse lifestyles: Arthropods live in different environments, from insects and spiders on land, to crustaceans and shrimps and crabs in the water, all of which have their own special physiological and behavioral characteristics adapted to their environment.

In conclusion, the main characteristics of arthropods are body segmentation, exoskeletons, foot structures, and a variety of lifestyle patterns, which make them rich in evolutionary and ecological adaptation.

Molluscs, invertebrates, molluscs, phylums, animals, arthropods are the largest categories in the animal kingdom.

Mollusca.

Molluscas are invertebrate mollusks and are the largest group of about 100,000 species except arthropods. The systems vary greatly, but they share common characteristics The body is soft and not segmented, and is generally divided into two parts: the head, the foot (some heads are vestigial or disappearing, and the foot is muscular) and the viscera and mantle (composed of the dorsal visceral mass, the mantle and the mantle cavity).

Arthropod.

Arthropods are the largest group in the animal kingdom, and the animals of the phylum Arthropod include more than one million species of invertebrates, accounting for almost 84 of all animal species, with diverse members. Symmetrical invertebrates, covered with an epidermis partly composed of chitin, which can be shed at regular intervals, and the epidermis is a protective device that acts as an exoskeleton and provides an attachment surface for muscles. The muscle sequence is complex, and some are specialized to maneuver flight and vocalization.

The exoskeleton of the appendage has joints, so it is called an arthropod. There are many special sensors. More than 879,000 species have been described, of which about 86 are insects.

It is divided into five subphyla. The body is symmetrical and consists of most body segments with different structures and functions, and can generally be divided into three parts: head, thorax and abdomen, but some species of head and thorax are fused to form cephalothorax, and some types of chest and abdomen are undifferentiated. The body surface is segmented by thick chitinous outer bones and appendages.

the high development of heterorhythmic segmentation; exoskeleton with a chitin protein complex; appendics segmented and related; The striated muscles are well developed and can contract rapidly; open-tube circulation; The invagination of the body wall forms the trachea as a respiratory organ; The excretory system is formed by the outward protrusion of the intestinal wall; The nervous system and sensory organs are well developed; The vast majority are dioecious, fertilized in vivo.

An important feature of arthropods is an exoskeleton covered with chitin, also known as the epidermis or cuticle. The exoskeleton is divided into different pieces of bon, and on the joint membrane between adjacent segments, the stratum corneum is very thin and prone to flexion and movement.

The cuticle of each somite is basically divided into 4 parts: 1 dorsal plate, 1 web plate, and 2 lateral plates. There are usually different changes due to secondary mergers or divisions. The tubular exoskeleton of the appendage also has joint membranes between the segments, and the joints can also be moved.

In most arthropods, the intersegmental membranes fold below the posterior edge of the previous somite exoskeleton. Some arthropods have vertebrate ball-and-socket joints. The exoskeleton sometimes protrudes into the body to form an internal protrusion that serves as an attachment point for muscles; Or the internal tissue ossifies into free pieces of bone for muscles in the body to attach to, and the exoskeleton is secreted by a layer of epithelial cells (called epithelial or hypothelium) underneath it.

The exoskeleton can be divided into 3 layers: from the inside to the outside: the inner epidermis, the outer epidermis and the upper epidermis. The inner epidermis is the thickest layer of the exoskeleton immediately following the epithelium, and the main components are a complex of proteins and chitin, colorless and soft, elongated and tortuous.

The outer epidermis is located on the outer side of the inner epidermis, which is thinner and precipitates calcium salts in the main components of protein and polysaccharide chitin, or rich in bone protein, and is the hardest part of the exoskeleton, generally in the internode membrane and other membranous areas, and because this layer is underdeveloped, it appears flexible. The upper epidermis is located in the outermost layer, is thin, and usually contains wax.