Phylum Annelida

Phylum AnnelidaSegmented Worms

DiversityLive in all parts of the world (except Arctic and

antarctic regions)Can be marine, freshwater, or terrestrial

Approximately 9,000 speciesRange in size from 1mm- 11 Feet

Common Earthworm is 9-10 inchesKnown as segmented wormsEx: leech, earthworm

Characteristics of All AnnelidsBody System: Tube within a tube

Inner tube is the straight line digestive tractExtends from mouth (first segment) to anus (last

segment)Outer tube consists of two layers of muscle, moist

skin, a cuticle, and secretion of slimy mucousFluid filled cavity between the two tubes

Contains a well developed circulatory systemNervous systemThread like kidneysReproductive organs

Characteristics of All AnnelidsBilateral SymmetryMetamerism (segmentation)

Increases the efficiency of body movementAllows for greater complexity of the body

systemsMuscular Structure

Both longitudinal and circular musclesSurrounded by moist cuticle (outer covering)

which aids in breathing

Characteristics of All AnnelidsSetae

Used for locomotionLeeches do not have these

Coelom is well developedCirculatory system is closedDigestive System is completeRespiratory System

Gas exchange occurs through skin, gills, or parapodia

Characteristics of All AnnelidsExcretory system

A pair of nephridiaNervous System

Double ventral nerve cord and pair of gangliaSensory System

Taste buds, photoreceptor cells and eyed with lenses (in most)

Reproductive SystemHermaphroditic or separate sexesMay have asexual reproduction

ClassificationKingdom Animalia

Phylum AnnelidaClass Oligochaeta

Examples: EarthwormsClass Polychaeta – means many bristles

Examples: lugworms, clam worms, bristlewormsApproximately 8,000 species

Class HirudineaExamples: leechesOften used in medicine to relieve swollen limbs, dry skin,

etc.

Worm compostingRecycling the organic waste of a household into compost

allows us to return badly needed organic matter to the soilWorm composting is a method for recycling food waste

into a rich, dark, earth-smelling soil conditioner.Worm compost is made in a container filled with

moistened bedding and redwormsAdd your food waste for a period of time, and the worms

and micro-organisms will eventually convert the entire contents into rich compost.

Composting DIY

Class OligochaetaEarthworms:• Burrow in soil• Come out at night to explore• Can drown if soil gets too wet• Diet: scavengers (eat dead,

decaying matter)• Have the ability to learn!

Class PolychaetaPolychaetes:• Ex: Christmas tree worm,

Fireworm, Scaleworm• Largest group of annelids• Mostly marine• Brightly colored or can be

dull in color

Class HirudineaLeeches:• Live mostly in freshwater• More abundant in tropical

areas• Most are carnivorous

(feed on meat, blood)• Have two brains!

Characteristics of Earthworm (most “famous” of Annelids)

Soil is natural habitatBurrows head first into soil (makes its burrow by

using the pointed head end to push soil aside)Eats soil for food (obtains nutrients/water from the

soil)Can feed on grass, leaf/scraps of organic matter

Also digest humus (dead, decaying matter)Head end is light-sensitive

Nocturnal—feed/eat/active during nighttime

Long, slender body (cylindrical)150-200 ring-like segmentsLocomotion/movement—performed by layers of

muscle in the body wall (circular bands of muscle)Ventral (belly) side has setae (bristle-like hairs) used

for movementMature worms have a clitellum (produces the egg capsule

at breeding time)—larger segment (lighter in color)Respiration—through its moist skin (cannot become dry

—worm would suffocate)

Characteristics of Earthworm (most “famous” of Annelids)

Organs:Pharynx—sucks in food (think of a vacuum)Esophagus—food enters here once enters mouthCrop—temporary storage (from esophagus)Gizzard—grinds food into small piecesIntestines—digestion and absorption occur hereAortic arches—-part of closed circulatory system,

contains 5 of these, maintains a steady pressure of blood to vessels

Ganglia—nervous system organ, brain

Characteristics of Earthworm (most “famous” of Annelids)

Nerve cord—runs from ganglia to each segment, provides nerves to body structures

Blood vessel—part of closed circulatory system, moves oxygen throughout body

Clitellum—reproductive organ, secretes mucus, stores eggs/sperm during reproduction

Setae—movement and reproductive purposesSegments—mouth-anus sensory/excretory organs are

attached to muscle wall of each segment Anus--excretionNephridium—excretory organ, excrete ammonia

Characteristics of Earthworm (most “famous” of Annelids)

Earthworm DissectionYouTube Earthworm Dissection

Other/Biosphere/UsesHelp to aerate the soilPrepare soil with nutrients from excretory waste

productsLeeches can be used for medicinal purposes (for

blood clotting issues)Earthworms: eat, fishing, aerate soil, etc

Characteristics of Earthworm (most “famous” of Annelids)

Earthworm Pictures!

Earthworm Pictures!