K.1 segmented worms
🌟 General Characteristics
Q: What is Phylum Annelida?
A: Segmented worms.
Q: What key feature defines annelids?
A: Segmented body structure.
Q: What body cavity do annelids have?
A: A coelom.
Q: Why is the coelom important?
A: It allows development of organs like blood vessels, muscles, and digestive structures.
Q: What systems become more specialized due to a coelom?
A: Circulatory, respiratory, excretory, and digestive systems.
🧬 Segmentation
Q: What are body segments in annelids called?
A: Repeating anatomical units along the body.
Q: What divides the coelom into segments?
A: Septa.
Q: Why is segmentation important?
A: It allows specialized organs and efficient movement.
🪱 Classes of Annelida
Q: What are the three main classes of annelids?
A: Oligochaeta, Polychaeta, Hirudinea.
🌱 Oligochaeta
Q: What is an example of Oligochaeta?
A: Earthworm (Lumbricus).
Q: What does "oligochaeta" mean?
A: “Few bristles.”
Q: What structure defines Oligochaeta?
A: Setae (bristles).
Q: How many setae per segment do oligochaetes have?
A: Two pairs per segment.
Q: What is the clitellum?
A: A thickened reproductive band that secretes slime during reproduction.
🌊 Polychaeta
Q: What is an example of Polychaeta?
A: Nereis (sandworm), tubeworms.
Q: What does "polychaeta" mean?
A: “Many bristles.”
Q: What structure do polychaetes have instead of setae?
A: Parapodia (fleshy lateral extensions).
Q: What is the lifestyle of many polychaetes?
A: Predatory or filter-feeding.
🩸 Hirudinea
Q: What is an example of Hirudinea?
A: Leeches.
Q: What is the main lifestyle of leeches?
A: Parasitic.
Q: What structures do leeches use to attach to hosts?
A: Anterior and posterior suckers.
Q: What is hirudin?
A: A chemical that acts as an anticoagulant and anesthetic.
🫀 Body Structure & Movement
Q: What muscles allow annelid movement?
A: Circular and longitudinal muscles.
Q: What do circular muscles do?
A: Constrict the body.
Q: What do longitudinal muscles do?
A: Shorten the body.
Q: Why can annelids move efficiently?
A: Muscle layers act independently of digestion.
🍽 Digestive System (Earthworm)
Q: What is the first digestive structure after the mouth?
A: Pharynx.
Q: What is the function of the crop?
A: Temporary food storage.
Q: What is the function of the gizzard?
A: Grinding food.
Q: What does the intestine do?
A: Absorbs nutrients.
Q: What are earthworm waste deposits called?
A: Castings.
🫀 Circulatory System
Q: Do annelids have a closed circulatory system?
A: Yes.
Q: What are the main blood vessels in earthworms?
A: Dorsal and ventral blood vessels.
Q: What are aortic arches?
A: Segmental vessels that act like hearts.
🧠 Nervous System
Q: What type of nervous system do annelids have?
A: Ventral nerve cord system.
Q: What is the brain structure in earthworms?
A: Bi-lobed dorsal brain.
🧽 Excretory System
Q: What organs do annelids use for excretion?
A: Nephridia.
Q: What do nephridia do?
A: Filter waste and release it through pores in the cuticle.
🧪 Reproduction
Q: Are earthworms hermaphroditic?
A: Yes.
Q: What is the role of the clitellum?
A: Produces mucus for reproduction and cocoon formation.
Q: Does fertilization occur inside or outside the earthworm?
A: Outside.
Q: What larval stage do earthworms produce?
A: Trochophore larva.
🌱 Ecological Importance
Q: How do earthworms improve soil?
A: They aerate it and improve water/nutrient flow.
Q: Why are earthworms important for plants?
A: They increase nitrates in soil, enhancing plant growth.
Q: What is the economic importance of earthworms?
A: Used as fish bait.
🩸 Leeches (Special Case)
Q: How do leeches feed?
A: By sucking blood from hosts.
Q: What does hirudin do?
A: Prevents blood clotting and reduces pain detection.
Q: Why are leeches used in medicine?
A: They improve blood flow after surgery by preventing clotting.