The three classes of annelids are Polychaeta, Oligochaeta, and Hirudinea. The Polychaeta consists of marine bristle worms. The Oligochaeta consists of aquatic or terrestrial earthworms.
The Hirudinea consists of leeches. An earthworm is shown in figure 1. Arthropoda refers to another phylum of kingdom Animalia, consisting of animals with jointed appendages and a chitinous exoskeleton. Arthropods can be aquatic, terrestrial or aerial animal forms. Arthropods are triploblastic animals, whose body cavity is a filled with blood or haemolymph. Thus, arthropods are haemocoelomates. Furthermore, the circulatory system of arthropods is an open circulatory system , consisting of a heart and an artery.
The body of the Arthropoda is segmented to head, thorax, and abdomen. The head is composed of pairs of antennae and compound eyes. Arthropoda was the first group of animals to develop a head. The jointed appendages can occur in pairs. Since the body of arthropods is covered with a chitinous exoskeleton, they shed their exoskeleton periodically to achieve body growth. This process is called molting or ecdysis. Arthropods consist of a complete digestive system with an anus and mouth.
The mouth is modified to chewing or biting. The respiration of arthropods occurs through gills, trachea or book lungs. The excretion of terrestrial arthropods occurs through Malpighian tubules. In aquatic arthropods, the excretion occurs through coxal glands or green glands.
The arthropods are unisexual animals. The five classes of arthropods are Crustacea shrimp, crayfish, and lobster , Arachnida spiders, ticks, mites, and scorpions , Chilopoda centipedes , Diplopoda millipedes and Insecta bees, butterflies, roaches and beetles. A bee is shown in figure 2. Annelida: Annelida refers to an animal phylum that consists of coelomates with elongated, segmented body. Arthropoda: Arthropoda refers to an animal phylum that consists of haemocoelomates with a segmented body, joint appendages, and chitinous exoskeleton.
Annelida: Annelids are commonly called segmented worms. Arthropoda: Arthropods are commonly called animals with jointed legs. The polychaete class of annelids is also dioecious, but most members of the other two classes are not.
For example, a single earthworm will produce both eggs and sperm. Two worms rub against each other to exchange sperm and to fertilize one another's eggs.
The polychaete class can also reproduce through epitoky. In some of these cases, part of the worm separates from the rest of the body and leaves the burrow to reproduce. The remainder of the worm stays behind in the burrow. Another difference between annelids and arthropods is their circulatory system. Annelids and humans have closed circulatory systems in which the heart pumps blood into vessels. The blood is always contained in the vessels -- it does not enter the rest of the body.
Arthropods, however, have open circulatory systems, so the blood actually pumps the blood into parts of the body cavity known as sinuses, where it surrounds tissues. Because the closed system is less efficient for oxygen transportation, many arthropods have supplemental systems for carrying oxygen to their organs.
Amy Jorgensen has ghostwritten more than articles and books on raising and training animals. She is also an amateur dog trainer. They do not possess an endoskeleton. However, the phylum arthropoda consists of animals with a segmented body, an exoskeleton, and paired appendages. Whereas, phylum annelid consists of segmented worms that possess transverse rings.
So, this is the key difference between arthropods and annelids. Importantly, a significant difference between arthropods and annelids is that the arthropods have a chitinous exoskeleton while annelids do not have an exoskeleton. Moreover, arthropods have a chitinous cuticle while annelids have a collagenous cuticle.
Besides, annelids are worms and do not have legs, but they have parapodia for locomotion, while arthropods have segmented appendages for locomotion. Therefore, this is also a significant difference between arthropods and annelids. Also, another difference between arthropods and annelids is that annelids usually have a closed circulatory system while it is an open system in arthropods.
Moreover, diversity is extremely high among arthropods compared to annelids. Arthropods are invertebrate animals that possess a segmented body, an exoskeleton, and paired appendages. Whereas, annelids are another group of invertebrates that are segmented worms by transverse rings.
Though arthropods have an exoskeleton, annelids do not. Furthermore, arthropods have an open circulatory system while annelids have a closed circulatory system. Insects, crustaceans, arachnids are several groups of arthropods while earthworms, ragworms, and leeches are some groups of annelids.
Thus, this summarizes the difference between arthropods and annelids. Reish, Donald J. He has more than ten years of diverse experience as a Zoologist and Environmental Biologist. Your email address will not be published.
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