Arthropods represent one of the phyla of kingdom Animalia. Arthropods are animals with jointed appendages and a chitinous exoskeleton. They are adapted to live in terrestrial environments. Some of these adaptations include reduced body size, presence of antenna and compound eyes, complete digestive system, and breathing through trachea, gills or book lungs. The excretion of nitrogenous wastes occurs in the form of uric acid in arthropods. The chitinous exoskeleton is shed periodically, allowing the growth of the body. Arthropods are unisexual animals that represent only one sex.
Key Areas Covered
1. What are Arthropods
– Definition, Facts, Classification
2. How Do Arthropods Adapt to Their Environment
– Characteristics of Arthropods
What are Arthropods
Arthropods are a group of animals with jointed appendages and a chitinous exoskeleton. Most arthropods live in terrestrial habitats. Some of them are aerial forms while a few can be aquatic. Arthropods have bilateral symmetry. They are triploblastic animals, whose body cavity is filled with blood or haemolymph. Thus, arthropods are haemocoelomates. Arthropods have a body segmented into head, thorax, and abdomen. The circulatory system of arthropods is open and consists of a heart and an artery. The five classes of arthropods are Chilopoda (centipedes), Diplopoda (millipedes), Crustacea (shrimp, crayfish, and lobster), Arachnida (spiders, ticks, mites, and scorpions), and Insecta (bees, butterflies, roaches, and beetles). A weevil, a type of beetles, is shown in figure 1.
How Do Arthropods Adapt to Their Environment
Arthropods are the largest animal phylum on earth. One million species of arthropods have been recognized worldwide. They show various types of adaptation to their environment. They are listed below.
- Most arthropods are small in size.
- Arthropods develop a prominent head, which is composed of pairs of antennae and compound eyes. Arthropoda was the first group of animals to develop a head.
- The jointed appendages of arthropods occur in pairs. One or two pairs of wings occur in aerial arthropods. This facilitates their propagation.
- The body of arthropods is covered with a chitinous exoskeleton. Exoskeleton provides support to the body and sites for the attachment of muscles. It also prevents water loss from the body. The process of shedding the exoskeleton is called molting or ecdysis; this facilitates the growth.
- Arthropods have a complete digestive system with an anus and mouth. Mouthparts of them are varied based on the type of diet they get. Some of them have lapping and chewing, sucking or siphoning
- Breathing occurs through gills, trachea or book lungs.
- The excretion of terrestrial arthropods occurs through Malpighian tubules. Nitrogenous wastes are excreted as uric acid, reducing the water loss from the body.
- Arthropods are unisexual animals.
Arthropods are the most successful animal phylum on earth since they are small in size and have wings, jointed appendages, chitinous exoskeleton, well-developed organ systems, etc. These features are adaptations that help them to survive in the environment.
1. “Adaptations of Arthropods.” Animals – Mom.me, Available here.
1. “Adult citrus root weevil, Diaprepes abbreviatus” By Keith Weller – released by the Agricultural Research Service (Public Domain) via Commons Wikimedia
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