Annelids

7th Grade BiologyChapter 11 Section 2

Page 386

Annelids

KingdomAnimal

PhylumPlatyhelminths

(Flatworms)

PhylumNematoda

(Roundworms)

PhylumPoriferaSponges

Segmented worms!

PhylumAnnelida

(Segmented worms)

Segmented WormsKingdomAnimal

PhylumAnnelida

(Segmented Worms)

ClassHirundinea(Leeches)

ClassOligochaeta

(Earthworms +)

ClassPolychaeta

(Marine Worms)

Earthworms(Class Oligochaeta)

• Each body segment has four pairs of setae• Two sets of muscles for movement

– Round muscles – Long muscles

• Well developed digestive system• Closed circulatory system• Small Brain• Hermaphrodites

Setae: bristlelike structures on the bodies of earthworms used for

movement

Setae

Digestive System

• Mouth• Pharynx (Throat)-muscular for food intake• Esophagus-tube which takes food to crop• Crop- Sac used for food storage• Gizzard- muscular structure that grinds soil and

organic matter• Intestine - absorbs nutrients moving them into the

blood• Anus - wastes are excreted• Nephridia- help filter waste out of blood

Digestive Organs

Circulation and Respiration

• Closed circulatory system-moves blood through vessles

• Aortic arches-- heartlike structure that pumps blood thru earthworms body.

• Dorsal blood vessel on top Ventral blood vessel on bottom

• Oxygen and carbon dioxide is exchanged through the skin.

Nervous System

• Small brain or ganglia is made up of a mass of nerve tissue

• Nerves in each segment join to form a main nerve cord that connects to the brain

Reproductive System

• Hermaphrodites

• Cannot fertilize their own eggs

• Seminal Vesicles- location of sperm production

• Seminal Receptacle-where sperm is received during copulation

Earthworm Mating

Reproductive Organs

Other Parts

• Clitellum- swelled gland 1/3 of the way down the earthworm that releases material for earthworm cocoons

Earthworm Benefits

• Help recycle nutrients in the soil

• Help aerate the soil ( move estimated 36000 pounds per acre of soil each year)

• Food source for other animals

LeechesKingdomAnimal

PhylumAnnelida

(Segmented Worms)

ClassHirundinea(Leeches)

ClassOligochaeta

(Earthworms +)

ClassPolychaeta

(Polychaetes)

Leech Facts

• Feed on blood of other animals

• Use anesthetic, so you do not feel the bite

• Can suck 2-10 times it’s own weight in blood

http://www.youtube.com/watch?v=u9HHS1uPFSo