Coelomate Worms: Annelids Chapter 13

Phylum Annelida Important Groups – Earthworms – Tube worms – Leeches Habitat – Aquatic: Marine or Freshwater – Terrestrial: soil

Phylum Annelida Food Source: – Predators, Scavengers, Filter feeders, & Herbivores First substrate feeders Unique Characteristics: – First group with closed circulatory system – Segmented – each segment as a complete, independent organism

Skeletal & Body System Hydrostatic skeleton for support and movement Bilateral symmetry Segmented – “metamerization” – Segments separated by septa – Separate coelomic compartments Coelomates: True body cavity Have Setae – bristle-like structures projecting from body (except leeches)

Muscular System & Movement Body wall made of circular & longitudinal muscles Burrowing - movement – Swallow sediments – do not push aside – Each segment moves independently

Nervous Communication Independent ganglions in each segment – Suprapharyngeal & subpharyngeal ganglia Nerve cords – Double ventral

Cardiovascular System Complete, closed circulatory system – Includes: capillaries arteries veins 5 hearts – Blood transports hormones, nutrients, & wastes

Respiratory System Respiratory pigments dissolved in blood plasma carry oxygen – Ex: hemoglobin – makes blood red – Blood can be colorless, green, or red Oxygen diffuses across body wall

Digestive Food Capture Continuous gut extending from mouth to anus with its own musculature

Excretory Waste Removal Excrete ammonia across body wall Nephridia – Excretory organ – Functions like kidneys

Reproductive System Sexual – Monoecious or dioecious – Possess gonads Asexual – Budding – Transverse fission “Strobilation”