Arthropoda with Characteristics

Introduction

Arthropoda is the largest phylum of the kingdom Animalia. The name Arthropoda means jointed appendages. It is a triploblastic animal that consists of three germ layers, outer ectoderm, inner endoderm, and in-between mesoderm. They are invertebrates. Organisms of phylum Arthropoda are coelomate and have an organ-system level of organization. The phylum mainly consists of crabs, lobsters, mites, spiders, and insects. Organisms are found almost everywhere and show a wide variety of adaptations. Insecta is the most diverse class of phylum Arthropoda. More than one million species of Arthropoda have been found, most of them were of class Insecta.

Habitat: Organisms of the phylum Arthropoda are found almost everywhere in the world. Copepods are mainly found in marine habitats. A wide range of crustaceans lives in the sea whereas jumping spiders are found in Mount Everest as well. Some specialized mites are found in Antarctica and brine shrimps are found in saltwater lakes. Some beetles are there which are found in hot springs. Due to its diverse habitat, phylum Arthropoda has a wide range of adaptations for survival in extreme environments. This is the reason why arthropodal characters are quite diverse in comparison to another phylum.

Symmetry: The body is mainly bilaterally symmetrical i.e. the body can be divided into two equal halves if divided longitudinally.

Level of organism: Organisms of phylum arthropoda show organ system level of organization. Therefore, the presence of a complete organ system is expected.

Coelom: Organisms are true coelomate which means the true body cavity covered by mesoderm is present.

Organ systems: The digestive system is complete with the presence of both mouth and anus. Respiration occurs through different kinds of organs like book lungs, book gills, gills, or the tracheal system. The tracheal system is mainly present in a class insect. The circulatory system is an open type. Hemoglobin is also absent in the blood. Sensory organs of the organism include compound eyes, antennas. Balancing organ statocysts is present in the organism. Excretion is done by Malpighian tubules and the organisms are generally uricotelic.

Reproduction: Organisms are mostly dioecious that is sexes are separate. Generally, sexual reproduction is observed in the organism. Fertilization is internal but can be both indirect as well as direct. Indirect development means the presence of a larval structure in the life cycle of organisms. Nymph is the larval stage of cockroaches. Organisms of the phylum Arthropoda are mainly oviparous

Body structure: True segmentation is present in the body of the organisms. The body is divided into the head, thorax, and abdomen. Head bears a pair of compound eyes. The exoskeleton of the arthropod is made up of chitin.

Example: Apis indica, Bombyx mori, Anopheles, Culex, Aedes, Laccifer

Conclusion

Phylum Arthropoda is the largest phylum in the kingdom of Animalia. About 9000 species have been found of phylum Arthropoda. Arthropodal characters are widely diverse because of their wide range of habitats. They are triploblastic, coelomate, bilaterally symmetrical organisms with true segmentation of the body. The body consists of three parts- head, thorax, and abdomen. Organisms of this phylum Arthropoda possess an open circulatory system which means organs get washed directly in the pool of blood. Respiration occurs through different kinds of organs like book lungs, book gills, gills, or the tracheal system. The circulatory system is an open type. Hemoglobin is also absent in the blood. Sensory organs of the organism include compound eyes, antennas. Balancing organ statocysts is present in the organism. Excretion is done by Malpighian tubules. Organisms are dioecious though development can be both direct and indirect.