Class 9 Biology – Phylum Arthropoda

Phylum Arthropoda is the largest phyla of the animal kingdom. Arthropoda is a Greek word, which means joint foot. The Phylum Arthropoda characteristics include a chitinous exoskeleton, segmented bodies, jointed appendages, and a well-developed nervous system. The Phylum Arthropoda examples include insects, arachnids, and myriapods. In this article, we will cover Phylum Arthropoda characteristics, examples, and their more in detail.

Phylum Arthropoda – Description

The Phylum Arthropoda represents one of the most diverse and abundant groups of animals on Earth. Phylum Arthropoda is characterized by their jointed legs and exoskeletons made of chitin. The animals belonging to Phylum Arthropoda are both aquatic and terrestrial. Some groups in Arthropoda are even adopted to fly and sometimes act as parasites. Arthropoda includes insects, mites, spiders, crabs, and lobsters. The exoskeleton in arthropods is secreted by the epidermis. They have segmented body. Among the one million described species of Arthropoda, insects contribute the major part.

The internal organs of arthropods are generally built on repeated segments just like the external organs. Their nervous system is a ladder-like structure that contains ventral nerve cords. Fusion of various segments forms their heads and fusion of ganglia of these segments forms their brains. The development of the ancestry of Arthropods traces back to the Cambrian time frame.

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Arthropoda

Phylum Arthropoda Characteristics

Following are the characteristics possessed by the organisms belonging to the Phylum Arthropoda

• The head of Arthropoda has a pair of compound eyes. 
• The level of organization in arthropods is organ-level organization.
• The compound chitin made their exoskeleton.
• Arthropods are unisexual.
• Fertilization in Arthropods may be internal or external.
• Arthropods can respire through their body surface area and their trachea.
• Arthropods have a well-developed digestive system.
• Arthropods have sensory organs like eyes, hair, and antenna.
• The body of Arthropoda has three parts:
  • Abdomen
  • Thorax
  • Head

Phylum Arthropoda Examples

Arthropods are considered the largest phylum in the whole animal kingdom. It includes the creatures like crabs, centipedes, millipedes, lobsters, insects, and mites. Here, given some examples of Phylum Arthropods.

• Ants
• Beetles
• Centipedes
• Crabs
• Scorpions
• Grasshoppers
• Cockroaches
• Lice
• Flies
• Mayflies
• Praying mantis
• Stink bugs
• Silverfishes
• Termites

Classification of Phylum Arthropoda

Phylum Arthropoda is mainly classified into six subphyla. They are:

Crustacea

Crustacea, the subphylum of Arthropoda consists of mostly marine or sea animals. Even though, some creatures of this phylum like crayfish and sow bugs live in fresh water and on land. Respiration in Crustacea happens through their gills and their surface. Their development is done through the larva stage. Crustacea have five pairs of appendages and two pairs of antennae. Excretion in Crustacea is done through antennal glands. Large Crustaceans are mostly dwelling and tiny Crustaceans like copepods are important as zooplankton because they are food for many large organisms.

Example of Crustacea

• Crab
• Copepod
• Daphnia
• Palaemon
• Shrimp

Crustacea sub-classes:

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

Chelicerata

These are mostly terrestrial animals. Arachnida is the class in subphylum Chelicerata with the most number of species like spiders, mites, and scorpions. These animals mostly live on land under stones, in leaves, and in vegetation. There are some animals, that live in fresh water and oceans. Excretion in these animals is done through Malpighian tubes. In chelicerates Antenna is absent and the abdomen is divided into thirteen segments. Respiration in Chelicerata is done through their gills and trachea.

Example of Chelicerata

• Araneae
• Limulus  
• Horseshoe crab

This subphylum is divided into three types:

•  Arachnida
•  Merostomata
•  Pycnogonida

Hexapoda

The organisms belonging to the subphylum Hexapoda are mostly terrestrial animals. Their body is categorized into three parts, head, abdomen, and thorax. Hexapoda has a pair of compound eyes. Excretion in these animals is done through Malpighian tubes. Respiration in Hexapoda is done through their gills and trachea. The abdomen is divided into 7 to 11 segments. Hexapoda has three pairs of appendages. Their development is indirect and there is a larva stage in the development of hexapods.

Examples of Hexapoda

• Ants
• Mosquitoes
• Tabernus

Hexapoda subphylum is divided into two classes.

•  Insecta
•  Entognatha

Myriapoda

Animals of the Myriapoda subphylum are mostly terrestrial animals. Respiration in Hexapoda is done through the trachea. Excretion in these animals is done through Malpighian tubes. Animals in this phylum have any number of legs. These animals have antennae on their head. Their body has numerous segments.

Example of Myriapoda subphylum

• Scolopendra
• Julus

Myriapoda is divided into four classes

• Symphyla
• Diplopoda
• Pauropoda
• Chilopoda

Onychophora

These arthropods are very small in size and most terrestrial animals. Onychophora’s body has small segments. Nephridia help in excretion and the trachea helps in respiration.

Examples of subphylum Onychophora

• Hallucigenida
• Peripatidae
• Peripatus

Trilobitomorpha

These arthropods are extinct. They are not present on the earth today. Scientists found them in the Paleozoic era. The bodies of these arthropods are divided into three lobes, two lateral lobes, and one median lobe. Their bodies mainly consist of three parts. They are the head, thorax, and pygidium.

Examples of subphylum Trilobitomorpha

• Trilobite
• Raphiophorida
• Kjerulfia

Conclusion: Class 9 Biology – Phylum Arthropoda

In conclusion, the phylum Arthropoda is the largest and most diverse group within the Animal kingdom, boasting a wide array of species adapted to various environments. From insects and arachnids to crustaceans and myriapods, these creatures exhibit remarkable characteristics such as chitinous exoskeletons, segmented bodies, and well-developed nervous systems. Understanding the details of Arthropoda provides valuable insights into the complexity and importance of these fascinating organisms in shaping ecosystems worldwide.

FAQs on Phylum Arthropoda

What are the Main Characteristics of Phylum Arthropoda?

Main characteristics of Phylum Arthropoda are exoskeleton made of chitin, segmented bodies, jointed appendages.

What is the General Structure of Arthropods?

General Structure of Arthropods includes body divided into head, thorax, and abdomen, with jointed legs and antennae.

What are the 4 Main Types of Arthropods?

4 Main Types of Arthropods are: Insects, arachnids, crustaceans, and myriapods.

What are the 7 Classes of Anthropods?

7 Classes of Arthropods are – Insecta, Arachnida, Crustacea, Diplopoda, Chilopoda, Merostomata, and Pycnogonida.

What is Hexapoda? Give Some Examples.

Hexapoda is a subclass of insects with six legs, and some examples includes ants, bees, and butterflies.

What is Arthropoda?

Arthropoda is a Phylum of invertebrates with jointed legs and exoskeletons, such as insects and spiders.

Why the Exoskeleton of Arthropods is Hard? Explain.

The exoskeleton of arthropods is hard because it’s made of chitin, a tough material that provides protection and support to their bodies. Chitin is a complex polysaccharide that forms rigid structures, offering defense against predators and environmental hazards.