What is the difference between setae and parapodia

Thus, setae and chaetae are structures that helped in the survival of organisms during evolution. Overview and Key Difference 2.

What are Setae 3. What are Chaetae 4. Similarities Between Setae and Chaetae 5. Setae are bristle, hair-like appendages found in both vertebrates and invertebrates. Its singular term is seta. In invertebrates, it is mainly present in annelids and crustaceans. In annelids, the setae are stiff in nature.

They help the annelids to attach to the surface and prevent backsliding during their movement. Furthermore, in some organisms, the setae act as the podia and enable movement.

In crustaceans, setae mainly line the oral cavity and sometimes are differentiated into scales, which enable them the capture the pray. In some insects, setae are poisoned or have the ability to act as a defence mechanism. The setae arise from the trichogen. It is also known as the bristle generator. They arise as hollow structures. Slow creeping movements of Nereis virens are carried out by the action of parapodia only.

During locomotion each parapodium performs two strokes - an effective or back stroke and recovery or forward stroke. The combined effective and recovery strokes of numerous parapodia propel the worm forward. The parapodia of the two sides work alternatively causing successive waves along each side of the worm. What are parapodia? Linica Uday. Aug 22, Explanation: Nereis is a genus of Polychaeta worms in the family Nereidae. Related questions How do I determine the molecular shape of a molecule?

However, cross-fertilization is preferred in hermaphroditic animals. These animals may also show simultaneous hermaphroditism and participate in simultaneous sperm exchange when they are aligned for copulation. Phylum Annelida contains the class Polychaeta the polychaetes and the class Oligochaeta the earthworms, leeches and their relatives. The many chetae of polychaetes are also arranged within fleshy, flat, paired appendages that protrude from each segment called parapodia , which may be specialized for different functions in the polychates.

The subclass Hirudinea includes leeches such as Hirudo medicinalis and Hemiclepsis marginata. The class Oligochaeta includes the subclass Hirudinia and the subclass Brachiobdella. A significant difference between leeches and other annelids is the development of suckers at the anterior and posterior ends and a lack of chaetae.

Additionally, the segmentation of the body wall may not correspond to the internal segmentation of the coelomic cavity. This adaptation possibly helps the leeches to elongate when they ingest copious quantities of blood from host vertebrates.

The subclass Brachiobdella includes species like Branchiobdella balcanica sketi and Branchiobdella astaci , worms that show similarity with leeches as well as oligochaetes. Figure 3. The a earthworm, b leech, and c featherduster are all annelids. Phylum Annelida includes vermiform, segmented animals.

Segmentation is seen in internal anatomy as well, which is called metamerism. Annelids are protostomes. These animals have well-developed neuronal and digestive systems.

Some species bear a specialized band of segments known as a clitellum. Annelids show the presence numerous chitinous projections termed chaetae, and polychaetes possess parapodia. Suckers are seen in order Hirudinea.