Introduction

Arthropods are animals with joint-legged legs, and you have probably seen a few of them. Insects, spiders, ants, bees, crabs, shrimps, millipedes, centipedes, and other venomous insects are most well-known. They are all classified as members of the Phylum Arthropoda, the Animal Kingdom.

This Phylum contains around 84 per cent of all known animal species. Arthropods can be found in every ecosystem on the planet and exhibit a wide range of adaptations. They can withstand temperature, toxicity, acidity, and salinity extremes. They have evolved to live on land, in the sea and the air.

Anatomy of the Arthropoda Phylum

These are divided into six categories. Arthropoda phylum kinds are shown below:

Crustacea

Crustaceans are all members of the Arthropoda Crustacea phylum; the name crustacean originates from the Latin crusta, shell. Crustaceans refer to an extensive group of animals with both sessile and active members. These include crabs, lobsters, shrimp, krill, copepods, amphipods and barnacles.

There is no internal skeleton, and the exoskeleton is formed of calcium. There are over 38,000 species in the world. “Insects of the Sea” describes nearly all of them as aquatic. Arthropods range in size from microscopic to enormous living creatures.

  • Their body is segmented and symmetrical on both sides.
  • They breathe through their gills and the surface of their bodies.
  • The head, thorax and abdomen are the three major parts of the body.
  • Biramous appendages are seen on each thorax and abdominal segment.
  • The body surface or the gills are used to breathe.

The Crustacea subphylum is organized into six classes. These are the following:

  • Branchiopoda
  • Remipedia
  • Cephalocarida
  • Maxillopoda
  • Ostracoda
  • Malacostraca

Trilobitomorpha

Sub-phylum Trilobitomorpha is a type of trilobite that can be seen. From the Cambrian to the Carboniferous periods, trilobites were a common creature in the waters. They were flattened oval arthropods with three longitudinal “lobes.” Trilobites could roll into a ball because all their body segments were articulated.

  • The body parts were not structurally differentiated.
  • A pair of complex eyes and antennae protruded from the top of the head.
  • Each appendage has two limbs.
  • They are arthropods from the beginning of time.
  • Their bodies are separated into three sections: head, abdomen, and pygidium.
  • There was only one class in the subphylum: Trilobita.

Myriapoda

However, the word Myriapoda is still widely used to distinguish these arthropods from insects, which are similarly terrestrial and tracheate but have fewer legs (three pairs), a significant trunk division into thorax abdomen, and the presence of wings in general. Millipedes, centipedes, and others are members of Myriapoda, a subphylum of arthropods.

Here are roughly 13,000 species in the category, all of which are terrestrial. However, the word Myriapoda is still widely used to distinguish these arthropods from insects, which are similarly terrestrial and tracheate but have fewer legs (three pairs), a prominent trunk division into thorax abdomen, and the presence of wings in general.

  • Antennae, two sets of jaws, and a pair of basic eyes are all present on the head.
  • They have many legs.
  • They breathe through their trachea and excrete through Malpighian tubules.
  • These are primarily terrestrial.
  • The trachea is responsible for breathing.

The following classes comprise the Myriapoda subphylum:

  • Chilopoda,
  • Diplopoda,
  • Pauropoda and
  • Symphyla.

Hexapoda

As far as describing species, the Hexapoda subphylum in the phylum Arthropoda is the largest (some arachnologists believe the free-living and parasitic mites are more diverse, but no one is sure if that is true). There are well over a million species of hexapods on land and in water.

Semi-aquatic springtails inhabit North American waters in approximately 10-15 species; because they are only found on top of streams and pods.

  • The thorax is divided into three sections.
  • Malpighian tubules are responsible for excretion.
  • The trachea or book lungs are used to breathe.
  • They demonstrate progress indirectly.
  • They have three pairs of appendages on their bodies.

Two classes exist within the Hexapoda subphylum:

  • Insects and
  • Entognatha.

Chelicerata

Arthropods such as Chelicerata have segmented bodies and jointed limbs, encased in cuticles made of chitin and proteins, heads formed of several segments that fuse during embryonic development, rather smaller coeloms and a hemocoel within which the blood circulates.

Chelicerates were once predators, but they have evolved to adopt a variety of feeding tactics, including predation, parasitism, herbivory, scavenging, and consuming decaying organic materials. Modern chelicerates cannot digest solid food, so they grind their food with chelicerae and pedipalps and then flood it with digestive enzymes.

  • There are no antennae on this creature.
  • Most of them live on land.
  • 13 segments make up the abdomen.
  • The trachea or the gills are used to breathe.
  • The trachea or gills are used to breathe.

The following classes comprise the Chelicerata subphylum:

  • Arachnida
  • Merostomata 
  • Pycnogonida

Conclusion

Arthropoda is by far the largest Phylum of invertebrates. This Phylum has an ancient history, and many organisms in this group are insects. Other members include spiders, centipedes, and crustaceans. As Arthropoda, their bodies are made up of the segments, the exoskeleton, and jointed appendages.

The phylum Arthropoda is the most prevalent. Arthropods have developed a rigid exoskeleton that covers most of their bodies. Another major advancement made by arthropods is their open circulatory system. Instead of veins and arteries, arthropods have a hemocoel. The hemolymph (like blood) lies on top of the animal’s organs, delivering oxygen and nutrients.