Phylum Annelida The Segmented Worms Common name Segmented

  • Slides: 12
Download presentation
Phylum Annelida The Segmented Worms

Phylum Annelida The Segmented Worms

Common name: Segmented worms Characteristics: ·Cephalization: Well-developed nervous system: nerve cord with ganglion in

Common name: Segmented worms Characteristics: ·Cephalization: Well-developed nervous system: nerve cord with ganglion in each segment and anterior brain ·Bilaterally symmetrical ·Organs within a true coelom (cavity within mesoderm) ·Compartmentalization of organs / movement of parts of body ·Closed circulatory system with five pairs of “aortic arches”

• Sophisticated digestive system: mouth – food enters pharynx – passes through esophagus

• Sophisticated digestive system: mouth – food enters pharynx – passes through esophagus – peristalsis crop – storage gizzard – grinding intestine – more digestion anus – waste exits

Intestine Gizzard Crop Esophagus Pharynx Mouth Earthworm anatomy

Intestine Gizzard Crop Esophagus Pharynx Mouth Earthworm anatomy

• Appendages: – Setae: a stiff hair like or bristle like structure –

• Appendages: – Setae: a stiff hair like or bristle like structure – Parapodium: Paired muscular bristle-bearing appendages used in locomotion, sensation, or respiration

Muscles • Circular muscles • Longitudinal muscles

Muscles • Circular muscles • Longitudinal muscles

• Nephridium: A tubule open to the exterior that acts as an organ

• Nephridium: A tubule open to the exterior that acts as an organ of excretion • remove nitrogenous wastes; wets skin • No gills/lungs—use diffusion • Most have red hemoglobin in blood • a red protein responsible for transporting oxygen in the blood

Reproduction • Most are hermaphroditic • testes in 10 th and 11 th segments

Reproduction • Most are hermaphroditic • testes in 10 th and 11 th segments • ovaries in 13 th segment • Clitellum stores eggs and produces “slime band” protective coat around eggs

Classes of Annelids Oligochaeta: earthworms, night crawlers, (aquatic) tubifex worms · 20 -45 tons

Classes of Annelids Oligochaeta: earthworms, night crawlers, (aquatic) tubifex worms · 20 -45 tons of soil/year/acre processed by worms on organic farms · each worm processes its own weight each day

Polychaeta: bristleworms, tube worms, featherdusters · marine worms with parapodia and (most) jaws

Polychaeta: bristleworms, tube worms, featherdusters · marine worms with parapodia and (most) jaws

Hirudinea: terrestrial / aquatic leeches · some parasitic, some free-living · medicinal anticoagulant “hirudin”

Hirudinea: terrestrial / aquatic leeches · some parasitic, some free-living · medicinal anticoagulant “hirudin”

Class Hirudinea The medicinal leech is best known as the organism used for blood

Class Hirudinea The medicinal leech is best known as the organism used for blood letting (people used to believe many health problems caused by "bad" blood). They are being used once again to remove blood from hematomas (areas of blood leakage) resulting from surgery (like re-attaching severed limbs, etc. ).