Annelida

By: Kiran BasavaIsabelle Nievera

http://folkworm.ceri.memphis.edu/ew-doc/GIFS/ew.logo.gif

Annelida

• Means “little rings” which resembles the annelids body, which is a series of fused rings.

• Live in the sea, freshwater habitats, and damp soil.

http://www.botswanagallery.org/thesis/A/img2/earthworms.jpg

Classes

Oligochaetea (earthworms)http://www.freewebs.com/invertebratezoology/Earthworm1.jpg

http://marinediscovery.arizona.edu/alex%20tuttle%20webpage/fireworm.jpg

Polychaeta

http://itsmeela.files.wordpress.com/2007/07/450px-leech_blutegel.jpg

Hirudinea (Leeches)

Body Cavity

• Present• Have a true coelom, a

body cavity completely lined by tissue derived from mesoderm

http://www.glogster.com/media/2/3/92/77/3927715.jpg

Body Symmetry

• bilateral symmetry http://www.sheppardsoftware.com/content/animals/images/clipart_earthworm.jpg

http://www.sheppardsoftware.com/content/animals/images/clipart_earthworm.jpg

Nervous System

• A brain-like pair of cerebral ganglia above and in front of the pharynx

• A ring of nerves around the pharynx that connects to a subpharyngeal ganglion, from which a fused pair of nerve cords runs posteriorly.

http://media-2.web.britannica.com/eb-media/37/73337-004-B0D75E62.jpg

Circulatory System

• Have a closed circulatory system

• 5 pairs of hearts• Blood vessels circle

esophagus and pump blood

http://infusion.allconet.org/webquest/img010.jpg

Digestive System

• Unsegmented digestive tract• Mouth Pharynx Esophagus Crop Gizzard Intestine

Anus

http://yhsbiology.wikispaces.com/file/view/digest.jpg/49088317/digest.jpg

Excetory System• Annelida have excretory organs called

nephridia, directly remove waste from the bloodstream

• In earthworms (class Oligochaeta), waste is used to fertilize the soil

http://image.tutorvista.com/content/excretion-and-osmoregulation/septal-nephridia-illustration.jpeg

Locomotion/Musculature

• Each segment of an earthworm is surrounded by a longitudinal muscle that coordinates with a surrounding circular muscle to allow an earthworm to move

• Polychaetes have parapodia (“almost feet”) to move, and polychaetes and leeches can swim

http://mfaucher.com/files/Uganda03/675dpi/ug14_25.jpg

Skeletal Type

• None, their bodies are composed a a series of fused segments with muscles

http://www.teachyourselves.co.uk/worm.jpg

Sensory structure/features

• Have tactile organs (touch), taste buds, photoreceptor cells, and some have eyes with lenses

• Palps and antennae are located on the head (tactile)

• Also have lateral organs- epidermal sensory cells that are responsive to light or touch

http://tolweb.org/onlinecontributors/app?service=external/ViewImageData&sp=3990

Reproduction

• Hermaphrodites• Cross fertilize by aligning to

exchange sperm, which is stored while an organ called the clitellum makes a cocoon that receives the eggs and sperm from the worm, and remains in the soil while embryos develop.

http://www.offthemarkcartoons.com/cartoons/2005-11-11.gif

Gas Exchange

• Earthworms have many tiny blood vessels in their skins, which function as their respiratory organs

• The blood has hemoglobin that carries oxegen.

• In leeches, most gas exchange occurs through the body wall

Unique Characteristics

• Easily recognized due to segmented bodies

• Most segments have the same internal structures repeated throughout the worm

• Leeches used to be used for blood letting, and today are used to drain blood that accumulates in tissues after injuries or surgeries

QUESTION #1

1. What type of body cavity do annelids have?

a. Coalomate

b. Pseudocoelomate

c. Acoelomate

d. none

Answer

A. COELOMATE

QUESTION #2

An annelid’s circulatory system includes how many pairs of hearts?

a.6

b.9

c.1

d.5

ANSWER

D. 5

QUESTION #3

Describe the skeletal type of annelids.

a.They have an exoskeleton.

b.The do not have one.

c.They have a cuticle

d.They have a hydrostatic skeleton.

ANSWER

B. They do not

have one

QUESTION #4

How do earthworms exchange gas?

a.Diffusion

b.They do not.

c.They have many tiny blood vessels in their skins, which function as their respiratory organs

ANSWER

C They have many tiny

blood vessels in their skins, which function as their

respiratory organs