Phylum Annelida

3 basic body plans of nearly all phyla in the animal kingdom

Acoelomate, pseudocoelomate, and coelomate

Body plan of annelids

Coelomate

___ body plan: characteristic of flatworms and maybe nemerteans

Acoelomate

___ body plan: found in a few v small animals

Pseudocoelomate

___ body plan: ___ lined w a ___ or ___

Coelomate; body cavity; peritoneum; membrane

Most annelids:

Marine

___: the division of the body into  ___ arranged in a ___

Metamerism; similar parts; linear series

The ‘head’ of annelids

Prostomium

The ‘body’ of annelids

Segmented trunk

The part of annelids that contains the anus

Pygidium

Internally: each segment is a ___ compartment separated from other by a ___ (wall)

Fluid filled; septum

The gut: a ___ and not ___

Tube; metameric

Annelids have a ___ skeleton

Hydrostatic

Hydrostatic skeleton: each segment is a ___ chamber that interacts w ___

Fluid filled; muscles

Circular muscles contract: longitudinal muscles ___

Relax

Circular muscles relax: longitudinal muscles ___

Contract

Metamerism: permits ___ of shape changes along the ___ of an annelid’s body

Localization; length

Metamerism: ___ and ___ can be restricted to ___

Widening; elongation; certain segments

Metamerism: ___ segments can do ___ things at the ___

Different; different; same time

Metamerism: probably evolved as an adaptation for ___

Burrowing

Gut is the ___ or ___

Alimentary canal; intestine

Digestion is ___

Extracellular

___ break down food

Enzymes

___: picked up by ___ and passed into the ___

Nutrients; cells of the gut; bloodstream

Dorsal blood vessel: moves blood ___

Anteriorly

___ blood vessel: basically the ___

Dorsal; heart

Ventral blood vessel: moves blood ___

Posteriorly

___ confined to ___: basically a ___ system

Blood; vessels; closed

No ___ in circulatory system precisely like those of vertebrates

Capillary networks

Annelids that are popular model systems in neurobiology

Leeches

Why leeches are a popular neurobiological model

Repeating segmental ganglia