Phylum: Annelida

Phylum: Annelida

• “ringed”, commonly called segmented worms

• Examples: earthworms, marine worms, leeches

Traits

• Segmented, round, wormlike bodies

Traits

• Bilateral symmetry

Traits

• cephalized

Traits

• Ventral nerve cord

Traits

• Tube-in-a-tube digestive system with specialized regions

Traits

• Closed circulatory system – blood doesn’t leave the vessels

Traits

• Paired nephridia

Traits

• Respire through their skin

Typical invertebrates

• Earthworms are about halfway between the simplest and most complex invertebrates

Classes

Oligochaeta

Polychaeta

Hirudinea

Oligochaeta

• “few bristles”, no parapodia• E.g. – earthworms, tubifex worms

Benefits of Earthworms

• improves aeration • increases water and nutrient movement

through the soil • Castings are rich in nutrients

Usually feed on decaying organic matter – can eat ½ -1 times their weight

• Charles Darwin went so far as to say of earthworms, “It may be doubted whether there are many other animals which have played so important a part in the history of the world, as have these lowly organized creatures.” He believed that earthworms are wholly responsible for the top layer of rich soil on the Earth

Earthworms vary in size from a centimeter to several meters long

Giant Gippsland Earthworm in Australia

Up to 15 feet stretched out!

Blue luminescent earthworms in Australia

• Striped earthworm in Australia just discovered in 2007

Worm Farming

• Used for compost• Sold for fishing bait

Tubifex Worms

Polychaeta

• “many bristles”, have parapodia, largest class of annelids• E.g. – marine worms, tube worms

Parapodia

• mainly used in respiration

Blood worm

Bristle worm

If touched, the setae will detach and lodge in the skin causing burning, itching, and numbness from the toxins they contain

Venomous Setae

Tube Worms – make a tube for protection

Marine worms

Oligochaeta

Polychaeta

Hirudinea

Hirudinea

• No bristles or parapodia, have suckers• E.g. – leeches (blood suckers)

Leeches are Ectoparasites

Leach attacking a slug

Leech Removal?• use your fingernail or something flat to

break the seal of their suckers

Irritating them can cause them to regurgitate their stomach contents in the wound, risking infection or disease

Medicinal uses

• Past – to suck out evil blood, to remove bruises

Medicinal uses

• Present – reattachment surgery, blood thinner

• Leech saliva contains compounds that reduce pain, prevent clotting and dilate blood vessels. This prevents the tissue from dying off and allows the body to reestablish good blood flow to the reattached part.

Summary: A 45-year-old, white male patient who suffered a complete avulsion of the upper two-thirds of his right ear. The ear was reattached by doing a microvascular anastomosis of a small artery anteriorly. No veins were available for anastomosis. Soon after anastomosis, there was obvious venous congestion. Medicinal leeches were used for treating venous congestion

24 Hours:Photograph shows severe venous congestion in the reimplanted ear following complete avulsion.

48 Hours:3 leeches have been applied every 8 hours. Following the initial application, obvious improvement was noted

6 Days:The entire reimplanted ear was viable and healing well.

72 Hours:3 leeches have been applied every 8 hours for periods of 15 to 30 minutes. Marked improvement in color with decreased swelling and congestion was noted.

Two Months: Complete survival of re-attached ear

Also testing to be able to…

• treat arthritis, blood clotting disorders, and varicose veins.

Demi Moore Leech Therapy?

http://www.youtube.com/watch?v=bYeqPvv5s_E

Giant Leeches

Earthworm Structure

Earthworm structure

• Prostomuim – 1st segment, before mouth, contains lots of sensory nerves

Earthworm structure

• Clitellum – thick band around the worm, involved in reproduction

Earthworm structure

• Setae – little bristles that give the worm traction for movement

Earthworm structure

• Mouth – entrance to the digestive system

Earthworm structure

• Pharynx – (throat) sucks in food

Earthworm structure

• Esophagus – carries food from the pharynx to the crop

Earthworm structure

• Crop – stores food, lets worm eat a lot of food at one time and digest it later

Earthworm structure

• Gizzard – grinds the food

Earthworm structure

• Intestines – finishes digestion, absorbs food

Earthworm structure

• Anus – exit of the digestive system

Earthworm structure

• Aortic arches – 5 pairs (hearts), pump blood

Earthworm structure

• Dorsal blood vessel – carries blood away from the hearts

Earthworm structure

• Ventral blood vessel – carries blood back to the hearts

Earthworm structure

• Brain – coordinates and controls the body

Earthworm structure

• Ventral nerve cord – carries messages between the brain and the body

Earthworm structure

• Ganglia – bundles of nerves

Earthworm structure

• Seminal vesicles – store sperm

Earthworm structure

• Seminal receptacles – receive sperm from other worm

Earthworm structure

• Muscles – both longitudinal and circular – lets them lengthen and shorten their bodies

Earthworm structure

• Cuticle – non-cellular layer that protects the skin from gritty soil

Earthworm structure

• Nephridia – collect, concentrate, and eliminate wastes, don’t lose as much water

Earthworm reproduction

• hermaphrodites – exchange sperm

• Night crawlers also mate on the surface. They are hermaphroditic but do not self-fertilize. Following mating, each worm forms a tiny, lemon-shaped cocoon out of a liquid secreted from its clitellum. The sperm and egg cells are deposited inside the cocoon, and it is buried. After a two- to four-week gestation period, the baby worms emerge.