Phylum AnnelidaKaitlyn Anticoli and Madeline Avallon

Phylum Classes1. Polychaeta Class

2. Aelosomata Class3. Clitellata Class (superclass)

a. Oligochaeta Subclass

b. Branchiobdella Subclass

c. Hirundinea Subclass

Basic Characteristics● annelid means "little

rings" ● distinguished by

segmentation and body cavity

● range in length from 1 mm- 3 m

● bilaterally symmetrical

Basic Characteristics● digestive tract● ability to survive in

most environments● possesses 3

separate sections: prosomium (mouth), trunk and pygidium (tail)

● cephalopods

Skeletal System● coelum: fluid-filled cavity that separates gut

from body wall● hydrostatic skeleton

○ coelum which creates hydrostatic pressure and acts as a hydrostatic skeleton

○ most primitive skeletal system

Circulatory System● true closed circulatory system● two main vessels are

○ dorsal blood vessel: blood moves anteriorly

○ ventral blood vessel: blood moves posteriorly

● aortic arches: "hearts"○ dark, expanded structures on either side

of the esophagus○ only function in pumping blood from the

dorsal to the ventral vessels

Digestive and Excretion System● annelids break down organic material to

create rich soil● have a mouth that connects directly to the

anus without an intermediate stomach○ allows annelids to continuously eat and

excrete waste as they burrow down through the soil

Reproductive System● normally sexual● gonochoristic or hermaphroditic● asexual reproduction: part of their tail is

released which grows into a new organism (fission)

● sexual reproduction: fluids are transferred from the male pore to the female ovipore.

Nervous System● primitive brain (ganglionic mass) connected

by a ring of nerves to a ventral nerve cord that runs the length of the body

● sense organs include eyes, taste buds, tactile tentacles, and organs of equilibrium called statocysts.

Evolved Characteristics● humans, like annelids, have a brain and

nerve cord (spinal cord)● frogs have a coelum

○ annelid coelum contains fluid that creates pressure and acts as hydrostatic skeleton

○ frog's coelum contains organs such as the lungs and is where lymph cirulates

● anthropods like insects are also segmented

Sea Mouse● short, broad, segmented body, ● found in moderately deep water● dorsal surface has 15 pairs of raised scales

○ the space between the scales and the body surface forms a channel for the flow of water carrying oxygen

● 6 to 8 in. long and 2 in. wide

Giant Feather Duster● marine segmented worms ● attached to rocks or sand● from 1/2 to 10 inches long● Encased in a translucent tan tube made of

protein and filtered particles● about 30 feather-like gills (radioles ) on each side of

their tube for respiration and feeding● covered in eyespots to know when danger is near to

retreat into their tube● live in groups in tide pools or near the low-tide line● feed on small particles and plankton floating in the water

Leeches● cylindrical or slightly flattened body with

suckers at either end for attaching to prey.● salivary secretions substances that promote

blood flow like hirudin● can be small enough to enter human body or

as big as adult human forearm ● do not feed vey often

Giant Australian Earthworm● largest is 13 feet long!● need water so rarely leave moist

underground● lay eggs that take year to develop● endangered because can't handle human

interaction/pesticides etc.● annual worm festival with Earthworm Queen

Colonial Polyps ● one-way digestive tract● prefer mild flow environments but benefit

from occasional stronger water flow● round with a mouth in the middle and a ring

of tentacles around the mouth● tentacles possess cells that sting, paralyze,

and catch prey

King Ragworm● prefer estuarine environment with mud● can grow to 24 inches● sharp teeth that grab and hold onto prey● locomotory feet

○ aid swimming○ circulate water○ bring food to worm

● predator