Round & Segmented Worms

3 Phyla of Worms Nematoda – Round worms (round as a toad) Annelida – Segmented worms What is the phylum for flat worms?

Nematoda (roundworms) Slender, unsegmented worms Range in size from microscopic to a meter Some are free living, and some are parasitic

Nematoda (roundworms) Have 3 germ layers What are the 3 germ layers? Are protostomes What does protostome mean?

Nematoda (roundworms) Have 2 openings in their digestive systems Means have both a mouth and anus Pseudocoelomates Fluid filled cavity only partially lined with mesoderm

Parasitic roundworms Trichinosis-Causing Worms Filarial Worms Ascarid Worms Hookworms

Trichinosis-Causing worms Terrible disease Adult worms live and mate in the intestines of their host Host include: humans, pigs, and other mammals Females carrying fertilized eggs burrow into intestinal wall and release larvae

Trichinosis-Causing worms Larvae travel through the bloodstream and burrow into organs and tissues Larvae forms cysts and become inactive in the host’s muscle tissue Life cycle complete when another animal eats muscle tissue containing these cysts

Filarial worms Found mostly in tropical regions of Asia Threadlike – live in the blood and lymph vessels of birds and mammals Transmitted from one primary host to another through biting insects MOSQUITOES In severe infections a large number or worms block the passage of fluids within the lymph vessels Causes elephantiasis

ELEPHANTIASIS

Ascarid worms Causes malnutrition in more than 1 billion people worldwide Spread by eating veggies or other foods that are not washed properly Matures in the intestines of host Produce eggs that leave body in feces

Ascarid worms Gets in new host by eating contaminated food or water Eggs hatch in small intestine and burrow into walls and enter bloodstream Go to lungs – then go into air passages – then to throat and are swallowed which sends them back to intestines

annelida Segmented worms Name means “little ring” because the segments look like rings The divider between the segments are called septa (singular septum)

question Why would having body segments be beneficial?

Body segments Can have segments that perform specific functions Some have multiple eyes Some have antennae Other sense organs Specialized for respiration

setae Bristles attached to body segments What are some possible uses for setae?

coelomates Annelids have a true coelom What is a coelom?

Classes within annelida Oligochaeta Hirudinea

oligochaetes Typically have streamlined bodies Relatively few setae compared to other annelids Live in soil or fresh water

Earthworm (oligochaetea) Use setae to keep from being pulled from the ground Clitellum – secretes mucus for eggs Hermaphrodite – has both male and female reproductive organs

External Structure Nephridiopore – opening into equivalent of kidney Seminal Receptacle Pore – sperm comes in through here Oviduct Pore – egg

hirudinea Leeches External parasites What do they eat? Have suckers on both ends of their body

Medicinal use of leeches http://www.5min.com/Video/Medicinal-Use-of-Leeches-416309592 Pros of using leeches medicinally Reduce swelling post surgery Help circulation in graft areas/reattachment areas Secrete an “anti-clotting” fluid – so helps relieve pressure in healing tissues