annelids phylum annelida: 15,000 species of segmented worms
TRANSCRIPT
Annelids
Phylum Annelida:
15,000 species of Segmented
Worms
Class Oligochaeta
• “Few bristles”
• Earthworms = Lumbricus terrestris
Class Polychaeta
• “Many bristles”
• Marine worms, sandworms
Class Hirudinea
• Leeches
Classification
• Common Name: Earthworm
• Scientific Name: Lumbricus terrestris
• Phylum: Annelida
• Class: Oligochaeta
• Other: Segmented Worms
Characteristics
• Body Plan: Tube within a tube; Segmentation = repeated units
• Body Cavity: Psuedocoelom “False Cavity”
• Symmetry: Radial
• Cell Specialization: Organs and tissues exist; repeated body segments past a certain point; insurance against injury
Life Support Processes
• Absorption: Intestine runs the entire length of the body
• Feeding: Soil enters Mouth > Pharynx (esophagus) > Crop (storage) > Gizzard (grinds food) > Intestine
• Digestion: Intestine = Chemical; Gizzard = mechanical
Life Support Processes
• Respiration: Through the skin, must be kept moist
• Circulation: Closed System - Dorsal Blood Vessel carries blood to head; Ventral Blood Vessel carries blood to back; Ring Vessel = heart (5 Aortic Arches)
• Excretion: Anus = solids; Nephridia = liquids
Life Support Processes
• Secretion: Intestine = digestive enzymes; Clitellum = mucus ring to make egg sac
• Response: Dorsal Ganglia = Brain; no sense organs other than touch receptors in skin
• Movement: Longitudinal and Circular Muscles, Setae
Life Support Processes• Reproduction: Sexual; hermaphrodites
that exchange sperm; Seminal Vesicle = produce sperm, Seminal Receptacle = receive sperm
• Support: Muscle tissues
Ecological Relationships
• Condition Soil; release nutrients
• Detritus Feeders; decompose leaves etc.
Body Systems Compared With Humans
• Nephridia = Kidney
• Intestine = Small Intestine
• Pharynx = Esophagus
Advancements Over Previous Phylum
• Closed Circulation
• Digestive Tract
• Muscles - greater degree of motion
• Segmentation = enables different parts of the body to function independently
Earthworm Diagram
• The largest of the Segmented worms is the African Giant Earthworm (Microchaetus rappi). This huge worm can reach a length of as much as 22 ft and can weigh over 3.1 lb!